Book Online
Coming Soon to West University

Understanding Soft Contact Lenses

Contact lenses eliminate the need for having to wear glasses, which can be beneficial for sports, cosmetic reasons, and the ability to see outside the limitation of a glasses lens.

In today’s world, with so many different outlets for getting contact lenses, it is more important than ever to understand why you should see your eye doctor yearly and how to properly care for your lenses.

 

What Does an Optometrist Consider When Prescribing Contacts?

When prescribing corrective lenses—whether they be glasses or contacts—your eye doctor takes many different parameters into consideration including: the distance between the correction and your eye (known as the vertex distance), what your primary working distance is (are you wanting to see best up close, far away, or at an intermediate distance?), the shape of your eye, the health of your eye, and many others.

Contact lenses are a little more complicated than glasses because they fit directly onto the eye and therefore need to sit just right to allow for optimal vision. Your eye doctor will take many different measurements before choosing the best lens for you—sometimes this takes multiple attempts!

Contact lens fittings can be broken down into two major categories—finding a lens that is comfortable and finding a lens that optimally corrects your vision.

At the beginning of a contact lens evaluation, the eye doctor must evaluate the health of your cornea—the very front clear structure of the eye. Your eyes need to be free of any surface disease or infection prior to wearing a contact lens.

Next, your eye doctor will take some measurements to determine what size lens would be best for your eyes, as well as mapping out the curvature of your cornea to make sure the lens is not too flat (resulting in a loose fit) or too steep (resulting in a tight fit) for your eye.

Arguably, the most important part of fitting a contact lens is ensuring that it properly corrects your vision. Since the lens sits directly on your eye, your glasses prescription will need to be converted to a contact lens prescription.

Yes, you read that right. Believe it or not, your glasses prescription and your contact lens prescription are not the same thing!

Glasses prescriptions and contact lens prescriptions can be converted interchangeably using several different complex equations. However, just because a person’s glasses prescription mathematically computes to a certain contact lens prescription does not necessarily mean that ordering the converted prescription will result in optimal vision.

Once your doctor has made all of these measurements and selected what is believed to be the “perfect” lens for your eye, they need to take a look at the lens on your eye to determine if this is actually the case.

The human eye is like a finger print—no two are the same. Therefore, your doctor will need to take your input into consideration when fitting your lens to make sure your vision is the best it can be. He or she may need to tweak a parameter or two to get your prescription exactly right.

Sometimes everything fits great and you may see great, but the lens is not comfortable. Your doctor may need to switch brands or materials to find a lens that is more comfortable to you.

Or, sometimes a lens fits great and is comfortable, but the contact lens needed for your exact prescription does not exist. Therefore, your doctor may have you try two different sets to determine which lens you see the best out of, and you may have to settle a little on not having “perfect” vision.

But wait, glasses can be made to your exact prescription, so why can’t contact lenses?

As noted above, contacts sit directly on your eye. The eye is a wet, round surface, so lenses tend to move around when blinking, looking to the right or left, up or down, etc. The main point to note here is that contact lenses have some movement whereas glasses lenses do not. This complicates things a little bit.

Contact lenses are also made in bulk by contact lens manufacturers. Since there is an infinite number of different prescriptions possible, contact lens companies have to put some limit to what they make, otherwise some lenses would be bought all the time, and others would sit on shelves for years and eventually go bad and need to get thrown away.

Therefore, unlike glasses that can be made exactly to a very specific prescription, contact lenses have to be estimated and altered to fit what is available. Your eye doctor has to make this decision each and every time your glasses prescription is adjusted.

Here’s an example patient to help explain this system:

Let’s say a person has a glasses prescription of -6.25 -3.25 X 163. After converting this prescription from glasses form to contact lens form, the “optimal” contact lens prescription would be:     -5.81 -3.11 X 163.

Prescriptions are written to the nearest quarter diopter (.00, .25, .50, or .75). For a patient with astigmatism, the available axes in contact lenses are to the nearest 10th, (i.e. X 010, X 100, X 180, X 160, X 170, etc.) Thus, this is where the doctor would need to do some educated trial and error work to find the lens that would best for this example patient.

A good place for the doctor to start would be a lens that is -5.75 -3.00 X 160. However, the doctor could also try a -6.00 -3.00 X 170, or a -5.75 -3.25 X160, or a -6.00 -3.25 X 170, or other combinations of these options.

Then, perhaps after all this calculated decision making, the doctor puts the lens on the patient’s eye and the lens rotates. Now even more calculations have to be considered to make sure the patient’s vision is corrected in the proper manner!

As you can see, it is not quite as straightforward as one might think!

 

Different Contact Lens Options

There are hundreds of different contact lens options in existence. In fact, every few months an entire book is published to give eye doctors the complete list of contact lenses and their available parameters.

Contact lenses are available as spherical only lenses (i.e. no astigmatism correction), or can correct for astigmatism as well. Astigmatic contact lenses are referred to as “toric” lenses.

Contact lenses that correct for astigmatism tend to be a bit more expensive, so if you have a low amount of astigmatism your eye doctor may try to adjust your prescription to be a spherical contact lens in order to help you save money. This does not work for all patients—only sometimes in those with very small amount of astigmatism (-0.25 to -0.50 diopters)

Contact lenses can also be used to change your eye color! In today’s market, essentially any color is available. Some of the most common colors are blue, green, purple, grey, or hazel.

Another of the most notable differences between contact lenses is their wear schedule. Some lenses are meant to be worn for 1 day only, others may be worn for up to a month, 3 months, etc.

It is very important that you know what your lens wear schedule is and that you discard and change out your lenses as recommended. Over-wearing your lenses can lead to infections and even permanent damage to your eyes.

Daily contact lenses tend to be a little more expensive, but are a great option for children, individuals who have allergies, those with dry eyes, or those who only like to wear lenses every now and again for special occasions.

Monthly lenses must be taken out every night and stored in a contact lens case. They tend to be a little more affordable than daily disposable lenses. It is recommended that these contacts be replaced on the same day every month (for example, the 1st of every month) to help to remember when to change lenses as to not over-wear an old lens.

There are also lenses that can be approved to sleep in, but there are not quite as many prescriptions options for these lenses as other types, as it is not recommended to sleep in contact lenses.

 

The Do’s and Don’t of Contact Lenses

Do NOT swim or take showers in your contact lenses. Bacteria and fungi within the water system are known to latch onto contact lenses. When these sit on your eyes all day long every day it can lead to some very serious infections.

Do replace your contact lens case every month. Bacteria like dark, warm, moist environments—like contact lens cases! You might be cleaning your lenses properly, but putting clean contacts into an old, contaminated contact lens case will only transfer the bacteria to your lenses, which will be put into your eyes, and will result in a nasty infection.

Do replace your contact lens solution each night. Letting solution sit in a case all day is asking for bacteria to move in and proliferate in the solution. Just as mentioned above, this can result in bad infections!

Do NOT sleep in your contact lenses. When we sleep, our eyes get less oxygen and dry out a little bit. When this happens, the contact lens shrinks up slightly and will tighten onto your eye—allowing even less oxygen to get to your eye. This is very dangerous!

Do replace your lenses as directed. If your lens is a monthly lens, it must be replaced after 1 month—even if you only wore it a couple of times! Lenses only stay “good” for a given amount of time. If you have a 2-week lens, it will go “bad” 2 weeks after it was removed from its foil package. Not properly disposing lenses after the time indicated by the manufacturer increaes your risk for infection.

Do discard contact lenses after they have expired. All boxes of contact lenses should be marked with an expiration date (if not, you shouldn’t be wearing that brand!). Just like medications, contact lenses expire. New contact lenses are stored in air-tight foil packets filled with a sterile solution. After the expiration date, the sterile solution has lost its effect and the lenses could be contaminated with bacteria. It is also possible that the expired lenses have lost their integrity and may no longer properly correct your prescription. Either way, it is not safe to wear expired lenses (or use expired solutions!).

Do NOT overwear your lenses. This is super important. Overwearing your lenses increases risk for infection, results in poorer optical quality, and can damage the structural integrity of the eye. One of the most common findings in contact lens over-wearers are corneal ulcers. These are very painful and can result in permanent vision loss, sometimes even blindness, if they occur on the central cornea.

Do clean your contact lenses every night. There are different types of solutions, but be sure yours has a disinfectant property to it and manually rub your lenses to ensure bacteria, debris, makeup, dirt, etc. are removed from the lenses prior to inserting them into the case for storage each night.

Do NOT fib to your eye doctor when they ask you questions about your contact lens care. Contact lenses are a wonderful tool for those who have prescriptions but do not want to be hindered by the glasses lifestyle. They are safe when used as directed. It is of utmost importance that you tell your eye doctor the truth about how you handle your contact lenses—they will not judge you, they only want what is best for your eye health. If you are not honest with your doctor, they may not be able to help you properly when problems arise. Who knows, there might be a better options to suit your lifestyle and preferred care regimen! Open conversations with your doctor are key.

 

Our eye doctors at Eye Theory in Houston, TX excel in the prescription of contact lenses, glasses and various eye diseases.  Call our optometrist at 832.831.7386 or schedule an appointment online if you would like to learn more about soft contact lenses.  Our eye doctor, Dr. Jonathan Tsao, provides the highest quality optometry services and eye exams in the Midtown, Downtown, West University, Museum District, Montrose, East Downtown, and Southside Commons (Southside Place) vicinities of Houston, Texas.

Important Glasses Measurements You Probably Don’t Know About

A pair of glasses is designed specifically for you. From the size of the frame to the resting position of your eyes within the lens, they can be customized precisely to provide you with the best vision possible.

This is important not only for vision, but also for aesthetic, comfort and functionality. Below are some of the measurements our opticians will take from you to help create the best glasses for your needs.

 

Pupillary Distance (PD)

This is the distance between the pupils of your eyes. More specifically, it is the measurement between your pupils, the black circle in the center of your eyes through which light enters.

This can be taken as a distance between the eyes or separate measurements for each eye. This distance can also vary depending on whether you are looking in the distance, at the computer, or up close for near tasks.

A tool called a pupillometer will often be used to determine these measurements. Additionally, precise markings of the pupil centers when you are wearing your frame of choice can also provide us with the numbers we need.

 

Glasses Measurements and Vertex Distance

This is the distance between the back surface of the glasses and the front of your eyes. It is often more important for those with higher prescriptions as the distance between the lenses and your eyes will affect the strength of the lenses.

The distance at which your eyes were tested in the exam room may differ from the frame you choose, and this can have a large impact on achieving optimal vision.

It is crucial for our opticians to measure the position of the lenses on your face and the specific distance between the lenses and your eyes to compensate for any differences.

 

Pantoscopic Tilt is the “Tilt” of Your Frame

The tilt of the glasses refers to the angle of the lenses in relation to your face vertically. Typically, the bottom of the lenses or frame will be angled towards your cheeks while the top of the frame is angled slightly away from your brow bone.

Ensuring that the tilt is appropriate and not too extreme in either direction is key for excellent comfort and vision. This is measured in-office using a special device that determines the angle of the lenses and can be adjusted on most frames to fit your face shape.

 

Face Wrap is the Frame Curvature

The face wrap refers to how curved the glasses frame is to the rest of the face. For example, those that want to use their glasses for sports or protection from wind would like to have high wrap to their glasses and lenses.

This is also measured in-office using a tool that determines the angle and extent that the frame is curving. Some lenses will not be able to handle large amounts of wrap due to a lack of flexibility.

 

The Fitting Height is Crucial

The vertical position of your eyes behind the glasses is also important. This measurement is crucial in patients with high prescriptions and particularly for those interested in progressive lenses.

This is because the wrong fitting height can interrupt the regions of the lens that are meant for optimal vision, specifically for near or distance vision, as the eyes may be sitting in the wrong spot. One of our opticians will determine the location of your eyes vertically and subsequently measure the height from the bottom of the frame.

 

Our eye doctors at Eye Theory in Houston, TX excel in the prescription of contact lenses, glasses and various eye diseases.  Call our optometrist at 832.831.7386 or schedule an appointment online if you would like to learn more about the various important glasses measurements our opticians utilize before finalizing your order.  Our eye doctor, Dr. Jonathan Tsao, provides the highest quality optometry services and eye exams in the Midtown, Downtown, Museum District, Montrose, East Downtown, and Southside Commons (Southside Place) vicinities of Houston, Texas.

Why You Should Try Multifocal Contact Lenses

Presbyopia, the inability to focus on objects up close, is a process that often begins to become more noticeable in an individual’s late thirties to mid forties. Multifocal lenses, usually being progressive lenses, are a great option that provide improved vision at various distances.

However, many also prefer to be free of glasses and look for a contact lens option. Today, there are a variety of lenses that are designed to provide the same multifocal ability as progressive or bifocal glasses lenses.

Our optometrist will find you the lens that fits your needs and eye anatomy, but it is a specific process that can take some time to fine tune. Below are some of the major components that we look for when deciding on a lens.

Your contact lens prescription

Each lens comes in a variety of powers, with the options varying between companies and product lines. After finalizing your prescription, our optometrist will make the necessary calculations and decide on the right lens for your specific needs and prescription.

In the case of high plus or minus lenses, only a few lines will have available options and the right lens will be selected for and trialled by you.

Contact lenses are chosen based on your eye’s anatomy

Each contact lens product line will come in specific sizes and curvatures. Your individual eye also has specific sizes and parameters.

It is important that our optometrist selects the correct parameters for you that allow for a good fit of the lens. A lens that is too tight or too loose can cause not only discomfort but also affect the amount of oxygen that gets to the eye.

In addition, our optometrist may also determine if you have a preference for one eye over the other. This is important because of the way some of these lenses are designed.

Select multifocal contact lenses are designed such that the center provides the correction necessary to see up close and the surrounding is for distance vision. The other eye will have the opposite correction in that the center provides proper distance vision and the surrounding area provides near vision.

Depending on your preference, our optometrist may select one eye over the other for primarily distance vision and vice versa.

Multifocal contact lenses can meet your visual needs

With the trial lens on, your vision will be assessed. It is important to keep in mind that multifocal contact lenses, while great for allowing viewing of varying distances, will often not provide vision as optimal as glasses.

There is often a compromise that must be made between the clarity of distance and near vision, as it is difficult to achieve perfect clarity at both ends. There is a happy medium that will be achieved that will allow for independence from glasses during regular daily tasks.

Depending on an individual’s visual needs, a prescription may be altered to allow for more near or distance clarity. It is common for our doctor to provide a variety of options for you to take home and test out in your daily life to see which ones work best for you.

 

Our eye doctors at Eye Theory in Houston, TX excel in the prescription of contact lenses, glasses and various eye diseases.  Call our optometrist at 832.831.7386 or schedule an appointment online if you would like to try multifocal contact lenses.  Our eye doctor, Dr. Jonathan Tsao, provides the highest quality optometry services and eye exams in the Midtown, Downtown, Museum District, Montrose, East Downtown, and Southside Commons (Southside Place) vicinities of Houston, Texas.

Understanding Your Glasses Prescription

When you receive an eye examination, you often leave with a copy of your prescription, which includes numbers for the exact specifications of the glasses you need. These numbers include the sphere, the cylinder, and the axis.

Sphere, cylinder, and axis can also all be broken down into different categories. Read on to learn about these specifications.

 

Sphere is the first number on your glasses prescription

The sphere power is the first number in the prescription and specifies the overall type and amount of power in the lens. It can be positive, indicating a hyperopic or farsighted prescription, negative, indicating a myopic or nearsighted prescription, or it can be zero.

If you have a farsighted prescription, your eyes have an easier time focusing far away and need some extra power for seeing things up close.

If you have a small to moderate number, you may have gone most of your life without needing glasses and only start requiring them when the focusing system inside your eyes begins to noticeably decrease in power (presbyopia).

For a nearsighted (ie: myopic) prescription, the eyes are naturally adapted to see at near without spectacles but require diverging power to make distant objects clear.

For low myopic prescriptions, you might only want your glasses or contact lenses to drive or see a movie, while for higher prescriptions, you pretty much need your glasses for everything you do.

 

The cylinder power is used to correct astigmatism

The second number is the magnitude of the cylinder power, which is used to correct astigmatism. It is usually specified in minus form, but can be converted to plus form by changing the entire prescription to an equivalent format.

Astigmatism is when the eye requires different powers in different orientations to see clearly, owing to its bending light like a football rather than a soccer ball: one direction with much more curvature than the other.

This can also be imagined in that someone with uncorrected astigmatism might see the vertical part of a capital letter L as perfectly clear while the lower horizontal part of it is blurry, or vice versa in any direction.

Everyone usually has a little bit of astigmatism, but some people may have none at all. Astigmatism is also not directly related to the amount of sphere power: you can have zero sphere power and a lot of cylinder power which still requires you to wear your spectacles or contact lenses.

 

The axis determines where to put the astigmatism in your glasses

The axis is the final number and is written as an angle made of three digits without the extra degree sign usually put in geometric angles.

This specifies the direction of the astigmatism correction, as it is a line that can be any degree or orientation from 180 degrees (a straight line left and right) to 90 degrees (a straight line up and down) and anywhere in between these.

The axis can be specified as with the rule (close to a flat horizontal line), against the rule (close to a straight vertical line), or oblique (somewhere in between these, close to a 45 or 135 degree angle).

As we age, we tend to move from with the rule astigmatism as children to against the rule as elderly.

 

Our eye doctors at Eye Theory in Houston, TX excel in the prescription of contact lenses, glasses and various eye diseases.  Call our optometrist at 832.831.7386 or schedule an appointment online if you would like to learn more about your glasses prescription is made and interpreted.  Our eye doctor, Dr. Jonathan Tsao, provides the highest quality optometry services and eye exams in the Midtown, Downtown, Museum District, Montrose, East Downtown, and Southside Commons (Southside Place) vicinities of Houston, Texas.

How to Treat a Corneal Abrasion

A cut to the eye can be one of the most physically painful experiences in an individual’s life. The front surface of the eye, the cornea, is a delicate structure important for transmitting light and protecting the eye.

This structure has many nerves and is very sensitive to all stimuli. People may experience trauma to the cornea via an abrasive injury, such as a scratch from a fingernail, a tree branch, or even a metal foreign object.

In these cases, a visit to the eye doctor is important to ensure a successful recovery.

What Causes a Corneal Abrasion?

As stated above, a corneal abrasion is a cut on the eye which can result from a variety of causes. This could be from a foreign object that enters the eye and disrupts the surface, either from impact or continued eye rubbing.

Metal, dirt, and sand are common examples. Another cause could be from blunt trauma, whether it is a fingernail or bush branch to the eye.

What to Do if You Have a Scratched Cornea

If one of the above scenarios has occurred and the cornea has been injured, here are the immediate steps that can be taken.

First, try to flush out the eye using saline solution, if it is available. It is best to avoid other sources of water, including tap water.

Other sources may contain microbes that can cause the abrasion to become infected, doing more harm than good. Any type of sterile water is best, and you could also use an over the counter antibiotic eye drop until you can get in to see our eye doctor.

Next, try blinking lightly. Your eyelids are designed to keep out debris and protect the eye, so gentle blinking may move the foreign body out of the eye.

However, in some cases, the particle may be trapped under the eyelid, making blinking even more painful and harmful as the particle repeatedly scrapes the cornea. If you feel that it is getting worse with blinks, stop blinking and try to keep the eye closed.

Generating tears is helpful in these situations. Your tears are constantly being replenished onto the surface of the eye and are useful in washing away debris.

Allow the eye to naturally wash away the particle if possible.

Make sure to visit our optometrists to ensure proper healing of the abrasion. Our optometrist will assess the depth and severity of the cut.

If the particle is still in the eye, our optometrist may apply an anesthetic eye drop and subsequently remove the offending item that may be lodged in the eye. This is done with specialized tools while viewing the cut and item under high magnification.

In some cases, a bandage contact lens may then be used to help with discomfort from the injury, and a prophylactic antibiotic eye drop may be prescribed for you to use to decrease the risk of an infection.

What NOT to Do When You Have a Corneal Abrasion

It is important to remember that rubbing your eyes with your hands can easily make the situation worse. In cases when the debris is trapped under the eyelid, rubbing your eyes will cause the particle to further scratch the front surface of the eye.

This can lead to more damage, although it is reversible in most cases. If there is an open wound on the front surface of the eye, touching the eye with non-sanitized fingers may also increase the risk of infection.

Stay away from using water sources other than saline solution. In some situations, such as a chemical eye injury, tap water will be a better option for rinsing than using nothing if saline is unavailable, but saline is ultimately the best option.

If you wear contact lenses, make sure to discontinue contact lens wear. This will encourage healing of the cornea and prevent infection.

As mentioned above, a bandage contact lens can be instilled by the optometrist, but this may differ from the lenses that you wear for vision correction. Only certain lenses are approved by the FDA for safe overnight wear and give an optimal healing environment for the eye injury.

 

Our eye doctors at Eye Theory in Houston, TX excel in the prescription of contact lenses, glasses and various eye diseases.  Call our optometrist at 832.831.7386 or schedule an appointment online if you think you have a scratched cornea or corneal abrasion.  Our eye doctor, Dr. Jonathan Tsao, provides the highest quality optometry services and eye exams in the Midtown, Downtown, Museum District, Montrose, East Downtown, and Southside Commons (Southside Place) vicinities of Houston, Texas.

Eye Problems and Down’s Syndrome

Down’s syndrome is a condition in which chromosome 21 is duplicated, resulting in three copies rather than just two. It is associated with intellectual, developmental, and physical changes.

The eyes are one component and there are a variety of conditions that individuals diagnosed with Down syndrome may be affected by or more susceptible to. Read on to learn about some of the most common ocular findings.

 

Refractive Error and Glasses

This refers to an individual’s prescription in corrective eyewear such as glasses or contact lenses in order to see as clearly as possible. Patients with Down syndrome are more likely to need corrective eyewear whether for nearsightedness, farsightedness, or astigmatism.

 

Strabismus is a Common Feature in Down Syndrome

Strabismus refers to an eye turn that the individual may have. This could be one eye turning in and out, or both eyes turning and switching back and forth. It could also be present at all times or only at some points in the day and associated with certain activities.

An eye more often turns inward, but in either case amblyopia or lazy eye may develop. This means that because the turned eye is not being used as frequently, it will not receive as much visual stimuli and its pathways to the brain will not fully develop, leading to permanent vision reduction in that eye if the eye turn is not fixed in childhood.

 

Down’s Syndrome Can Cause Keratoconus

At the very front of the eye is the clear cornea, which is thinned in this condition, causing the fluid from inside the eye to push outwards. This causes the cornea to bulge outwards into a cone shape and distorts the curvature, affecting vision. This condition has been shown to be associated with eye rubbing and our optometrist will check to make sure that there are no underlying causes inducing this.

Cataracts

A cataract refers to the clouding of the lens within the eye, causing blurry vision or a spot in vision. If noted, our optometrist will assess to see how severe the cataract is and, if needed, refer the patient to receive surgical treatment to replace the lens. Patients with Down syndrome are at higher risk for either congenital cataracts (present at birth) or developing cataracts as they age earlier than the general population.

Glaucoma

This is a group of disorders that refer to the death of the nerve cells at the back of the eye, which are responsible for providing peripheral vision. This is often associated with higher eye pressure but this is not the only variable.

Treatment includes eye drops, instilled everyday, to lower eye pressure or certain laser procedures that help with outflow of the fluid within the eye to lower the pressure. Individuals with Down syndrome are at higher risk for higher eye pressures and glaucoma.

Blepharitis

This is a condition that leads to inflammation of the eyelids and the glands within them. It is often associated with a dry or burning feeling in the eyes and redness. Eyelid hygiene is an important component for this condition and it can be treated with eyelid cleaning, warm compresses, steroids, or antibiotics.

 

Our eye doctors at Eye Theory in Houston, TX excel in the prescription of contact lenses, glasses and various eye diseases.  Call our optometrist at 832.831.7386 or schedule an appointment online if you would like to learn more about how Down’s syndrome can affect the eyes.  Our eye doctor, Dr. Jonathan Tsao, provides the highest quality optometry services and eye exams in the Midtown, Downtown, Museum District, Montrose, East Downtown, and Southside Commons (Southside Place) vicinities of Houston, Texas.

Unique Glasses and Contact Lens Options

In addition to regular spectacles and contact lenses, there are a number of lesser known options for vision correction. These are often built for certain work or play activities or specific eye conditions. Read on to learn more about some of these unique options.

 

Photosensitive, Tinted, and Color Contact Lenses

Contact lenses are becoming more technologically advanced all the time as new materials and designs are experimented with. Recently, a product has been introduced that combines the technology of Transitions lenses into a soft contact lens. Transitions lenses are photochromic, which means they darken in response to ultraviolet (UV) waves that exist in sunlight.

Darkening in this way helps to limit UV exposure to the eyes and prevent excessive brightness on a sunny day. They do visibly darken in the sun, but they are not a replacement for a regular pair of dedicated sunglasses. These contact lenses can be highly useful for people who spend a lot of time outside or for athletes in outdoor sports.

There are also colored and tinted contact lenses, which serve different purposes. Colored lenses are for aesthetic means, subtly changing the outward appearance of the iris, which is the colored part of the eye. Depending on the interaction of the lens and iris colors, many appearances can result in the end.

Tinted contact lenses are for visual purposes. They can enhance the ability to discern color or contrast differences. They can also be used in people with low vision or other eye and brain conditions to aid visual comfort and reduce symptoms.

Protective or Task-Specific Goggles

Goggles can be used for many activities, usually for more physical ones where the goggles must be tightly held to the head and eyes.

Goggles are often utilized in sports for vision correction, eye protection, or both. They can be customized to suit whatever needs a patient desires. For example, swim or ski goggles can be built with your prescription in them and can be tinted according to your needs as well.

These lenses are also useful in work that poses a hazard to the eyes. Safety glasses, as well as goggles, can be customized with your prescription while also providing adequate eye protection.

Vocational or Avocational Lenses

There are also various customized solutions for work and play. You may know of the traditional bifocal lens design, where a visible line separates an upper lens area built with the distance prescription from a lower area for the near prescription. This same design can be used in several different ways.

For electricians and pilots, for example, the bifocal design can be inverted so that near correction is on the top, allowing the clear vision of fine details above the head, and distance correction is on the bottom. Trifocals can also be used, where an intermediate lined portion is built between the distance and near portions of the bifocal, for those that require correction at specific distances.

Finally, there are lenses specifically designed for a day on the golf course. Most of the lens is built for distance, but there is a small portion in the corner made for seeing the scorecard and the tee. Other special variations exist and can always be customized to suit your visual needs.

 

Our eye doctors at Eye Theory in Houston, TX excel in the prescription of contact lenses, glasses and various eye diseases.  Call our optometrist at 832.831.7386 or schedule an appointment online if you would like to learn more about some of our unique eyewear solutions.  Our eye doctor, Dr. Jonathan Tsao, provides the highest quality optometry services and eye exams in the Midtown, Downtown, Museum District, Montrose, East Downtown, and Southside Commons (Southside Place) vicinities of Houston, Texas.

How Pregnancy Can Affect Your Eyes

In addition to the many other bodily changes taking place during pregnancy, a mom-to-be can also have changes in the eyes. These are usually transient and go back to normal after the pregnancy, but it is wise to keep a close watch on them with an eye examination if changes to vision are occurring. This article will outline some of these possible changes.

Your Glasses Prescription May Change When Pregnant

It is common for the mother to experience blurry vision due to a change in her refractive error, which can also be understood as a change in her degree of nearsightedness, farsightedness, or astigmatism as measured in her glasses prescription.

This is due to increased fluid retention throughout the body during pregnancy, including within the eye. One location for this is within the cornea, the clear front surface of the eye, causing a change in its thickness and curvature. It can also occur in the natural lens within the eye as well.

This would in turn alter the prescription needed to allow one to see clearly. This change is temporary and will likely return to normal after delivery.

It is common that our optometrist will wait six to nine weeks after delivery to update your prescription for glasses or contact lenses.

 

Gestational Diabetes Can Occur During Pregnancy

During pregnancy, women can develop gestational diabetes, defined as an increase of glucose in the blood during pregnancy that usually resolves after delivery.

Diabetes on its own can have detrimental effects to the health of the eyes in addition to the rest of the body if it is not well controlled for long periods of time.

Gestational diabetes usually does not get bad enough to cause these changes or symptoms, but it may exacerbate pre-existing diabetes by making blood sugar more difficult to control and regulate.

Other risk factors for diabetic retinopathy include coexisting hypertension, preeclampsia, greater severity and duration of diabetes, etc.

If you have an eye examination during your pregnancy, our eye doctor will find anything out of the ordinary if it is present and manage it accordingly or inform your other doctors of the changes.

Dry Eyes May Also Worsen

As mentioned previously, fluid can accumulate in the cornea during pregnancy, causing a decrease in sensitivity at the front of the eye.

The eyes are thus less responsive to debris or dryness in the eyes, exacerbating the effects of dry eyes due to a lack of activation of the body’s defense responses like tearing.

In addition, pregnancy and its associated hormonal changes disrupt the cells that are responsible for creating the watery fluid that makes up the tear layer.

This is key as it helps keep the eye moisturized, nourished, and healthy overall. Common symptoms of dry eye disease include a gritty, burning feeling and are often transient as well.

Mild dry eyes experienced during pregnancy can be managed with interventions like artificial tears and hot compresses, but there is a lot that can be done if the signs and symptoms are more intense and pose a risk of eye damage. 

Contact lens intolerance may also be experienced, secondary to symptoms associated with dry eye disease. For this reason, it is common to wait six to nine weeks after delivery to get fitted for contact lenses again.

 

Our eye doctors at Eye Theory in Houston, TX excel in the prescription of contact lenses, glasses and various eye diseases.  Call our optometrist at 832.831.7386 or schedule an appointment online if you would like to learn more about more ways pregnancy can affect your eyes.  Our eye doctor, Dr. Jonathan Tsao, provides the highest quality optometry services and eye exams in the Midtown, Downtown, Museum District, Montrose, East Downtown, and Southside Commons (Southside Place) vicinities of Houston, Texas.

The Basics of Keratoconus

Keratoconus is a condition that causes thinning and bulging of the clear front of the eye, the cornea. There are a variety of causative factors for keratoconus and more is being understood about its diagnosis and treatment all the time. This article will outline keratoconus, its causes, and its treatment.

What is Keratoconus?

The cornea is the front transparent surface of the eye and is largely responsible for focusing light onto the back of the eye, the retina, to allow for clear vision.

When there are deformities or changes in the curvature of the cornea, vision is therefore affected. Keratoconus is when the central cornea thins and the pressure from fluid inside the eye pushes it forward, leading to a bulging out and, if severe, a cone shape at the front of the eye.

It is a progressive disease with the highest rate of change in the teenage years and twenties with the process completing around age thirty.

The rate of progression can vary and the condition can sometimes progress later on in life as well or occur following a surgical procedure involving the cornea.

Symptoms of keratoconus include reduced vision even when corrected with glasses or contact lenses and inconsistent and highly variable prescriptions.

If the cornea is severely thinned and bulged, a break can occur where fluid from inside the eye drains into the cornea itself, leading to severe pain and visual disturbance. This acute condition, called hydrops, resolves with time and proper treatment.

What Causes Keratoconus to Occur?

Keratoconus is under constant study and causative factors are being investigated all the time. Family history and other genetics like ethnicity can play a role.

Excessive eye rubbing is an important risk factor as it increases eye pressure and strain on the cornea, leading to further degeneration.

Eye rubbing is associated with allergic or atopic conditions that cause the eyes to itch. Another possible cause can be refractive surgery, as this procedure involves altering and thinning the cornea in order to change the power of the eye.

This is why extensive testing of the cornea must be done before laser surgery to ensure that this does not occur.

Keratoconus is also associated with other genetic or connective tissue disorders, like Down syndrome and Marfan syndrome.

How is Keratoconus Treated?

In the early stages of keratoconus, it is often easily corrected with glasses or soft contact lenses. In the later stages, vision will be optimal only with the use of rigid gas permeable (RGP) lenses or scleral lenses.

RGP lenses are hard lenses that are smaller than the diameter of the colored part of the eye. These lenses will often take some time to get used to but provide excellent vision for patients.

They sit on the front surface of the eye and create a tear layer between the cornea and the lens that corrects the keratoconic irregularity and allows for better vision. Scleral lenses sit on the white part of the eye and are larger than RGP lenses.

They are also more comfortable and easier to get used to than RGP lenses. There are also hybrid lenses, which have a RGP center and soft contact lens edge, allowing for better comfort while still optimally correcting vision.

Corneal cross-linking is another treatment option for patients with keratoconus. This procedure helps to slow the progression of the cornea bulging outwards and maintains the integrity of the cornea as it is.

The procedure involves riboflavin (vitamin B2) being applied to the front surface of the eye with ultraviolet radiation exposure for 30 minutes. This makes the cornea stronger and more resilient against further change.

In severe and advanced stages of keratoconus, penetrating keratoplasty may be needed. This procedure involves transplanting a cornea from donor tissue and replacing the cornea of the patient.

Following the surgery, the patient will often be fit with a scleral lens for optimal vision.

 

Our eye doctors at Eye Theory in Houston, TX excel in the prescription of contact lenses, glasses and various eye diseases.  Call our optometrist at 832.831.7386 or schedule an appointment online if you would like to learn more about keratoconus.  Our eye doctor, Dr. Jonathan Tsao, provides the highest quality optometry services and eye exams in the Midtown, Downtown, Museum District, Montrose, East Downtown, and Southside Commons (Southside Place) vicinities of Houston, Texas.

The Causes and Treatments of Uveitis

If you have ever visited an eye doctor for light sensitive and sore eyes, you may have been diagnosed with uveitis, prescribed various medications for treatment, and possibly undergone laboratory testing to find an underlying systemic cause, if present. You may have visited the optometrist several times during the course of your treatment. Uveitis is common and can be caused by various factors. This article explains classifications, causes, and treatment of uveitis.

The Types of Uveitis

Uveitis means inflammation of the uvea, the vascular layer of the eye that houses the iris (colored portion), ciliary body (focusing muscle and fluid producer), and choroid (full of blood vessels). This inflammation results from an immune reaction carried out by the body inside these tissues, where immune cells and other mediators cause swelling and pain.

Swelling is what causes the extreme light sensitivity commonly reported in certain types of uveitis. The iris houses the pupil, the dark hole in its center, which the iris is causing to constantly increase or decrease in size in response to light and other stimuli.

If the iris becomes inflamed and swollen, these movements will cause great pain, just like moving a broken arm would. If uveitis is located further back in the eye and is not affecting the iris, there may be minimal pain but reduced vision because of inflammatory cells affecting structures needed for seeing and causing cloudiness of the fluids inside the eye.

Uveitis is classified through several means and there are many forms. It can be taking place in just one part of the uvea, at the front, middle, or back, or all of them at once. It can happen just once or recur several times. It might last days to weeks or become chronic for months.

What Causes Uveitis to Ocurr?

Uveitis might have an autoimmune cause, where the body attacks its own cells because it recognizes them as foreign and hostile tissue. It might also be caused by infections, trauma, or, rarely, cancer.

Usually, however, a uveitic episode has no identifiable cause, and if it is not severe or does not recur, no further testing will be done to look into it. Uveitis with an unknown cause that is localized to the iris is the most common type of all.

 

How Do We Treat Uveitis?

Uveitis is treated by reducing the inflammatory response within the eye, as this inflammation can lead to other problems if left alone. This reduction in inflammation is usually brought about with antiinflammatory corticosteroid eye drops, dosed every hour or two to rapidly calm down the immune response.

If severe or located at the back of the uvea, oral or injected steroids might be needed. After the uveitis is nearly gone, the frequency of taking these drops will be decreased very slowly so that the uveitis does not suddenly flare up again. For this reason, it is vital to follow our eye doctor’s instructions exactly.

In addition to the steroid drops, our optometrist will likely prescribe drops to make your pupils bigger, which will stop the iris moving in response to light and reduce the amount of immune cells entering the eye. This will decrease pain, speed healing, and prevent the inflammation from damaging other parts of the eyes.

If there is a clear underlying cause of the uveitis, such as an infection in the eye, that underlying cause will be treated by our eye doctor or referred as necessary to the appropriate medical provider.

 

Our eye doctors at Eye Theory in Houston, TX excel in the prescription of contact lenses, glasses and various eye diseases.  Call our optometrist at 832.831.7386 or schedule an appointment online if you would like to learn more about uveitis.  Our eye doctor, Dr. Jonathan Tsao, provides the highest quality optometry services and eye exams in the Midtown, Downtown, Museum District, Montrose, East Downtown, and Southside Commons (Southside Place) vicinities of Houston, Texas.

When Should My Child Get an Eye Exam?

There are many recommended health care appointments for children, and a comprehensive eye examination with an eye doctor is an important part of these. It may be confusing as to when you should bring your child for an eye examination and what can be done at each age.

This article will explore expert recommended guidelines for children’s eye examination intervals and what to expect from these appointments. In addition, the information here may be different if our optometrist finds certain conditions that they want to watch more closely.

0 – 2 Years: One Eye Examination Between 6 – 12 Months of Age

Although young and unable to do a typical eye examination, infants are able to have their eyes examined for various entities that can affect their development. After birth, hospital staff check for basic eye functioning and any noticeable diseases, like infections or the media of the eyes not being clear.

Our optometrist can check the eyes again between 6 – 12 months of age, where they are doing simple objective tests to check again for opacities in the eyes, glasses prescriptions that are outside of normal levels and can impact development, eye turns that require prompt treatment, etc.

These are short appointments that can do a great deal for a child if an issue is found.

 

3 – 5 Years: At Least One Eye Exam Between 3 – 5 Years of Age

As the child grows older, a more thorough eye examination is possible that can more precisely determine variables like the glasses prescription, which can be increasingly important as the child begins school.

This can be quite important as changes in the eyes that are not likely to be noticed by parents, like different refractive errors between the two eyes, can lead to amblyopia, or “lazy eye.” Amblyopia results when an eye does not have a clear image during the childhood years until age 9, causing the brain to not develop proper connections to that eye.

If the problem is corrected before age 9, proper function can develop, but if correction occurs afterwards, then there may be residual lack of vision in that eye.

 

6 – 18 Years: Once Before First Grade Then Annually Thereafter

As kids grow older into school, sports, and other activities, closely looking after their vision remains important. Even once we are beyond the ages where amblyopia could be a problem, optional correction of refractive error is important to optimize learning.

Treatment of errors in how the eyes focus, and how they work and move together, are also important for school and, especially, homework. Contact lenses may become important for sports and other extracurriculars like performances.

If a child is nearsighted, methods exist to reduce the rate that their prescription grows, leading to a smaller prescription overall when they finish growing.

Parents sometimes believe that if there is an issue with their child’s vision, they will be able to see it themselves, and put off routine eye care for their kids.

On the other hand, when an issue is found in an eye examination that was not previously known about, some parents blame themselves for not bringing their children in sooner. The best way to avoid this feeling, and to maintain the eye health of our kids, is to just simply get their eyes examined at proper intervals.

 

Our eye doctors at Eye Theory in Houston, TX excel in the prescription of contact lenses, glasses and various eye diseases.  Call our optometrist at 832.831.7386 or schedule an appointment online if you would like to set up an eye exam for your child.  Our eye doctor, Dr. Jonathan Tsao, provides the highest quality optometry services and eye exams in the Midtown, Downtown, Museum District, Montrose, East Downtown, and Southside Commons (Southside Place) vicinities of Houston, Texas.

How Do Your Eyes Work?

Have you ever wondered how your eyes actually see? It is an incredibly complex and intricate process that allows light rays to contact your eyes and transmit signals to the brain in an instant.

Beyond simply getting through all the structures of the eye and being properly focused on the back of the eye, the retina, these signals must then be propagated throughout the entire length of the brain to be processed at the very back of the brain and skull and fed into many other brain areas. Read on to learn more about this process.

Front to Back of Your Eye

Light rays first contact the transparent tear film and cornea at the front of the eye. These structures bend or refract the light for the first time as it enters the eye. It proceeds through the aqueous humour, a watery substance surrounding the colored iris, and is refracted further as it transmits through the natural lens behind the iris.

It carries on through the gel-like vitreous humor near the back of the eye before contacting photoreceptor cells near the most outer layer of the retina at the back of the eye.

These photoreceptor cells finally change these light signals into electrochemical signals that are then transmitted forward through the retina along various cell types.

At the front edge of the retina, ganglion cells transmit the signals along their nerve lengths which run from the eyes back into the middle of the brain. These are cells with very long nerves attached to them, similar to cells in the spinal cord with long lengths to transmit signals throughout the body.

In the eye, the visual signals travel along the ganglion cells as they join together in the optic nerve as they exit the eye.

 

From Your Eye to Your Brain

The optic nerve from each eye runs backwards from the eye and joins together with the other optic nerve near the front of the brain. At this point, some fibers cross over from each nerve to the other, meaning that some visual information from each eye is actually processed on the complete other side of the brain.

All of these nerves run further back and come to the thalamus, a sensory relay station for the entire brain. They connect with new cells that begin processing of the visual information being received, and these cells in turn pass the signal further back.

Nerve fibers then run primarily through other parts of the brain until they reach the primary visual cortex near the extreme backwards edge of the brain and skull. At this point, information from each eye is processed together for the first time.

 

How the Brain Processes What the Eye Sees

Depending on the type of visual information reaching the primary visual cortex, it is then sent to different areas of the brain for final processing. For example, highly detailed or color oriented information is sent to the temporal lobe of the brain for form information processing.

Spatial or motion oriented information might be sent to the parietal lobe. There is also feedback to previous points in the visual pathway like the thalamus to determine how further visual information is filtered and stored.

All of this occurs in an instant to provide us with incredible amounts of visual information about our world, and it is a process that is still under study.

 

Our eye doctors at Eye Theory in Houston, TX excel in the prescription of contact lenses, glasses and various eye diseases.  Call our optometrist at 832.831.7386 or schedule an appointment online if you would like to learn more about how your eyes see and work to provide information to your brain.  Our eye doctor, Dr. Jonathan Tsao, provides the highest quality optometry services and eye exams in the Midtown, Downtown, Museum District, and Southside Commons (Southside Place) vicinities of Houston, Texas.

 

Corneal Abrasions and Eye Injuries

Most of us try our best to take care of our eyes. When something comes close to our faces that might hit us, we immediately shut our eyes and turn our faces away to protect them. Even with caution, however, injuries to our eyes still happen and these often affect the clear front of the eye, the cornea. Below is explained how injuries to the cornea commonly proceed, what treatment for them entails, and some ways to prevent their occurrence and recurrence.

Types of Eye Injuries

When an injury occurs to the cornea that scratches its surface but does not pierce it, this is called a corneal abrasion. There will be immense pain when this occurs and likely some light sensitivity will develop afterwards as well. The cornea can heal very quickly, within a couple of days depending on the size, when this happens, but steps must be taken to ensure that this healing proceeds normally. Scratches can also occur as a result of debris lodged under the upper eyelids, and these must be removed.

Sometimes, a small bit of a fast moving object can enter into the cornea and embed itself there. This can be a piece of metal, wood, dirt, etc. The cornea is tough and can often stop these foreign body projectiles, but they must be removed to prevent scarring and further damage. If the cornea is completely pieced or perforated, more complex surgical treatment may be required depending on the extent of damage deeper in the eye and on how large the entrance hole is.

Regardless of the source of the injury, corneal trauma carries a secondary risk. The wound itself heals quickly, but requires months to completely reattach to the underlying tissue. This means that the area that was injured has an increased sensitivity to further damage and may spontaneously lift up with the eyelids when first waking in the morning, reopening the original injury site. This is called recurrent corneal erosion.

Corneal Abrasion Treatment

Our eye doctors will usually either put on antibiotic eye drops in office or prescribe them to prevent infection of the injury. If something is stuck in the eye, it will be removed if possible after the eye has been numbed with eye drops. This can be done with various metal tools like forceps or tweezers and tiny hockey sticks, or with motorized drills that gently scrape off dirty tissue.

If there is nothing in the eye, the loose edges of a corneal abrasion may be manually removed to quicken healing. If the wound is large, a bandage contact lens may be put on your eye to shelter it while it recovers, then removed after a few days.

Other drops may be used depending on how inflamed the eye is, such as corticosteroid eye drops to reduce inflammation or painkiller eye drops if you are in a great deal of pain. Drops that dilate your pupils help both with pain and with speeding healing of inflammation within the eyes.

 

How to Prevent Corneal Abrasions and Eye Injuries

Obviously, avoiding risky activities for the eyes and wearing safety glasses when performing activities with eye hazards are both useful ways to prevent eye injuries. In addition, after an initial injury has occurred, one can prevent recurrent corneal erosion by using lubricating eye drops often during the day and hypertonic ointment before bed at night. This ointment provides a barrier between the eyes and the lids and dries out the cornea, reducing the chance of the lids ripping the cornea open in the morning and causing the injury to recur. Medications such as steroids or doxycycline may also sometimes be prescribed to help healing and thus reduce the chance of this happening.

Our eye doctors at Eye Theory in Houston, TX excel in the prescription of contact lenses, glasses and various eye diseases.  Call our optometrist at 832.831.7386 or schedule an appointment online if you would like to learn more about corneal abrasions and other eye injuries.  Our eye doctor, Dr. Jonathan Tsao, provides the highest quality optometry services and eye exams in the Midtown, Downtown, Museum District, and Southside Commons (Southside Place) vicinities of Houston, Texas.

The Do’s and Dont’s of Contact Lenses

The use of soft contact lenses in today’s society has grown exponentially since their initial development. The amazing lens materials available and the various uses for contact lenses have contributed to their success. With the simplicity of these medical devices today, it is easy to forget the importance of maintaining the best hygiene practices for contact lens use. Below are some of the most important Do’s and Don’ts to keep in mind when taking care of your lenses and ensuring that your eyes are protected from infection.

DO Rub and Rinse

For those that are not wearing daily disposables, cleaning the lenses before going to bed is a key step in the hygiene routine. The best way to clean them is to place the lens in the middle of your palm, add some solution, and rub both sides of the lens with your middle finger. After this step, you can insert it into the peroxide or saline solution to be stored overnight. This will remove the protein and fat deposits that build up on the lens during the day

DON’T Sleep in Contact Lenses

This is often a tough one to remember for patients as it can be easy to accidentally fall asleep in the lenses. Unfortunately, this is one of the most common risk factors for infection. Overnight, the eye receives less oxygen and thus is less able to protect itself from invading microbes.

 

DO Replace Your Contact Lenses Regularly

If you are wearing monthly lenses, make sure to discard them 30 days after opening the package. Many people mistake the discard time for the number of days that the lenses are in the eyes but the best way to prevent infection is to discard the lenses according to the designated schedule. This means, for example, that even if you only wore the lenses 4 days out of the 30, you still need to discard them. Increased amounts of time outside their packaging can increase infection rates, induce more eye dryness, and cause irritation.

 

DON’T Use Tap Water

It is important to remember that contact lenses should never touch tap water. In fact, the lenses should only be in contact with specific disinfecting solutions or saline. Tap water is especially concerning as there are microbes in the water that can adhere to the lens and cause an infection. So, whether you need to rinse the lenses in order to remove debris or rewet them, make sure to never use tap water.

 

DO Clean and Replace Your Contact Lens Case

Contact lens storage cases (for monthly or biweekly lens wearers) are hot spots for bacterial growth and about 50% of cases will be contaminated. It is important to remember to clean the cases after each night of use. The best routine would be to dump out the rest of the solution, rinse the case out with contact lens solution, wipe the case and lids dry, and turn them upside down on a clean tissue. Ideally, these cases are also replaced every month or, at most, every 3 months.

DON’T Swim With Your Contact Lenses

Lakes, swimming pools and ocean water have a variety of bacteria and chemicals that can stick onto the lenses. This exposes your eyes to dangerous organisms that have the ability to damage the front surface of the eye permanently. The only time this may be done is if daily disposable contact lenses are used and are thrown away immediately upon exiting the water after a short time frame of use (i.e. 1 hour of swimming lessons).

DO Use Hydrogen Peroxide Disinfection

Monthly and biweekly lenses will need to be stored in solution overnight for up to 30 or 14 days, respectively. The best way to store them overnight and kill possible bacteria on their surfaces is in a hydrogen peroxide solution that will clean the lenses while you sleep. This solution often comes in a bottle with a red cap that is easy to identify so that it is not mistaken for a bottle of saline. This is because if hydrogen peroxide touches the eye, it will sting and burn the eye temporarily. A special case is needed to use this solution, as a disc at the bottom of the case will neutralize the solution overnight and allow the lens to be used in the morning directly from the case.

Our eye doctors at Eye Theory in Houston, TX excel in the prescription of contact lenses, glasses and various eye diseases.  Call our optometrist at 832.831.7386 or schedule an appointment online if you would like to learn more about the do’s and dont’s of contact lenses.  Our eye doctor, Dr. Jonathan Tsao, provides the highest quality optometry services and eye exams in the Midtown, Downtown, Museum District, and Southside Commons (Southside Place) vicinities of Houston, Texas.

Why are there Floaters in My Vision?

Depending on your age and eye medical history, you may have noticed a few or many floaters in your vision. Floaters are black dots or squiggles that you may see moving around in your vision, more obvious when you look at a light background or are somewhere with high illumination. When you move your eyes, they move with your gaze. These form in the vitreous humour, the gelatinous filling near the back of the eye. Often, we have a few floaters that our visual system gets used to with time, but there are also reasons why new floaters might appear later on in life. Some of these are normal, and some can be signs of something wrong in the eyes. Read on to learn about some common causes of floaters.

Posterior Vitreous Detachments (PVD)

The most common, and most harmless, reason to develop a new floater is the change in composition of the vitreous with age. As we grow older, this gel becomes more liquid-like and shrinks, pulling back from the retina and forming pockets of material that become a floater, or a posterior vitreous detachment. You may have some floaters even when you are young, but as we grow older you will always acquire more. Gradually seeing some more floaters in your vision through the years is normal, but there are other symptoms that can accompany them that signal something wrong with your eyes, and these will be explained below.

 

Vitreous and Preretinal Hemorrhage

When the vitreous pulls away from the retina with age, as explained above, sometimes it can tear blood vessels in the retina and lead to some bleeding that will show up as floaters in your vision. This bleeding can also result from trauma or other disease processes going on in the body, such as diabetes, sickle cell disease, or blood vessel blockages. These diseases can cause new, fragile blood vessels to grow from the retina into the vitreous, and these can then easily bleed to block vision.

Any bleeding like these described will cause a sudden and dramatic increase in the number and size of floaters in your vision and can completely block your vision if a full vitreous hemorrhage occurs. This can last for 2-3 months while the blood is cleared from the eyes. This shows the need to protect your eyes from trauma and to get your eyes checked regularly with one of our eye doctors, especially if you have underlying medical conditions that can manifest in the eyes.

Retinal Breaks and Floaters

A retinal break, tear, or detachment (retina peeling off) is the most urgent cause for sudden formation of floaters. Other symptoms often accompany this, such as lightning flashes of light in one’s vision, a foggy film appearance to vision in one eye, or the appearance of a dark curtain over one’s vision. If you are experiencing these symptoms, see one of our eye doctors immediately, as you may require urgent surgery in the coming days to prevent you from losing vision in that eye.

 

Our eye doctors at Eye Theory in Houston, TX excel in the prescription of contact lenses, glasses and various eye diseases.  Call our optometrist at 832.831.7386 or schedule an appointment online if you would like to learn more about floaters and vit.  Our eye doctor, Dr. Jonathan Tsao, provides the highest quality optometry services and eye exams in the Midtown, Downtown, Museum District, and Southside Commons (Southside Place) vicinities of Houston, Texas.

Glaucoma and Eye Pressure Testing

One of the most common tests completed at the optometry office is the Non-Contact Tonometer (NCT), more often known as the “air puff test” or “glaucoma test”. To many patients, it is a mystery what this test is truly measuring but here is a quick run-down of the purpose of this test and its importance. 

 

Eye Pressure and Glaucoma

At your eye exam, our optometrist will often want to keep a record of your eye pressure, which is the pressure exerted in the eye from the fluids acting within/ around it. The importance of this measure is that, like other parts of the body, it is important to maintain a normal value. 

Eye pressure can have small fluctuations in the short term due to a variety of factors (i.e. body posture, exercise, eye movement, time of day) that do not have a detrimental effect on the body. The most important change that your optometrist would find significant would be a large increase or decrease in eye pressure. Low pressure could indicate leakage of internal fluid or intraocular inflammation. A pressure that is too high could indicate changes in blood pressure, disease, or injury. High IOP is also a strong risk factor for glaucoma, a disease that can decrease the size of your visual world slowly without your awareness.  

 

There are a variety of ways that your eye pressure can be measured: 

 

Indentation Tonometry

This refers to a method of indenting a small area on the cornea, the front surface of the eye. The amount of force needed to indent a specific amount of the cornea is measured, but this technique is rarely done today.

 

Applanation Tonometry

This method uses a force (air or physical pushing) to applanate (or flatten) a specific small area of the cornea. The force and area flattened is measured and used to determine the pressure. 

The Goldmann Applanation Tonometer, Perkins Tonometer, Tonopen and i-Care are all instruments that utilize a probe to physically push into the cornea a small depth. Our optometrist will be looking to see how much pressure needs to be exerted on the front surface in order to flatten the cornea a specific amount. Our optometrist may instill an eye drop prior to the procedure to numb the eye so you will not feel any sensation of the probe. This also does not affect the health of the eye.

The Non-Contact Computerized Tonometer is commonly used for assessing eye pressures. This is an automated test that produces a puff of air that flattens the cornea. The value that is measured is the amount of time it takes for the cornea to be flattened a specific amount, meaning that the longer it takes for the air puff to flatten the eye, the higher the internal pressure. The thickness of the cornea can affect the measurement of the eye pressure so this is often automatically accounted for after the air puff is delivered and the final IOP is calculated.

 

Our eye doctors at Eye Theory in Houston, TX excel in the prescription of contact lenses, glasses and various eye diseases.  Call our optometrist at 832.831.7386 or schedule an appointment online if you would like to learn more about how we use eye pressure to assess your risk of glaucoma.  Our eye doctor, Dr. Jonathan Tsao, provides the highest quality optometry services  and eye exams in the Midtown, Downtown, Museum District, and Southside Commons (Southside Place) vicinities of Houston, Texas.

Contact Lenses for Beginners

Considering joining the wonderful world of contact lenses? Not sure how much it will cost to start? Here is a quick guide for things to consider and costs to account for. 

 

Types of Contact Lenses Based on Replacement Frequency

The frequency in which one will need to replace the lenses is an important factor when considering which lenses to purchase. In certain cases, the optometrist may require you to select a specific replacement frequency, for the necessary purpose of promoting healthy conditions for your eyes. In the case where you may be given the option, your options will include daily, bi-weekly, or monthly replacement.

Daily contact lenses are replaced with every use. This means that each lens can only be used for one day then thrown out. The benefit of this is that daily lenses eliminate the need to store the lens in a case overnight, negating the possibility of contamination and subsequently decreasing the risk of eye infections. It eliminates the need to purchase saline solution (unless preferred to rinse off the lens if dropped). The trade-off is that more lenses will be needed and there is a higher cost to them. Though the most expensive option, daily lenses are overall the best for eye health and contact lens comfort.

Monthly contact lenses are the opposite in that a new lens is worn for one month then replaced. These lenses must be stored in a cleaned contact lens case overnight using preferably hydrogen peroxide solution. These lenses cost less but are not as easy to clean as daily lenses and the cleaning process includes a rub and rinse step. This also means that these solutions must be purchased. This adds some cost though the monthly modality is still the cheapest way to go.

Bi-weekly contact lenses are the middle option in that they are replaced every two weeks and will also require a solution for the lenses to be stored in. 

 

What to Expect at Your Contact Lens Exam

The journey to getting your first pair of contact lenses starts with an assessment with your optometrist. This will likely be a separate appointment from the annual eye exam as it requires additional time and measurements.

The optometrist will investigate which lenses are best suited for you based on various findings such as the amount of lipid in your tears, the sizes of different ocular components, the activity of choice you will be using the lenses for, and how often you plan on wearing them.

Our eye doctor may then give you some lenses to try on the same day or order some in with your correct prescription. After trying on these lenses for a week or two, the optometrist will want to see you back and make sure that the fit was comfortable and did not cause any complications on your eye.

They may also make adjustments at this exam and order a new lens. When they find that everything is acceptable, you may be good to order your 3, 6 or 12 month supply. Remember, when buying from an optometry office for 6 month or annual supplies, certain lenses may have rebates that are only available from your eye doctor.

 

Contact Lens Follow Up Care

From this point, many people forget that it is important to return to their eye care practitioner annually to ensure that there are no long term complications from the lenses (i.e. inadequate levels of oxygen to the eye, dry eye, systemic changes that affect the eye) and that the eye is still in good condition to continue contact lens wear.

This exam is also a great opportunity to check in and see if there are any new technologies in contact lenses. Recently there have been new colour contacts, transition lenses (changes to be darker in sunlight and helps with light sensitivity), and multifocal lenses for astigmatic eyes on the market. 

 

Our eye doctors at Eye Theory in Houston, TX excel in the prescription of contact lenses, glasses and various eye diseases.  Call our optometrist at 832.831.7386 or schedule an appointment online if you would like to learn more about contact lenses.  Our eye doctor, Dr. Jonathan Tsao, provides the highest quality optometry services  and eye exams in the Midtown, Downtown, Museum District, and Southside Commons (Southside Place) vicinities of Houston, Texas.

Scleral Lenses: The Contact Lens You’ve Never Heard Of

Many people use soft contact lenses for their daily vision correction needs. Sometimes, however, these may not be enough to address your vision, eye health, or comfort needs with contact lenses. Other, more specialized options exist in such cases, and one of these options is the use of scleral lenses. 

 

What is a Scleral Lens? 

A scleral lens is a large diameter, rigid contact lens that vaults over the entire front clear part of the eye, the cornea, to sit comfortably on the white part of the eye: the conjunctiva and sclera. It differs from the regular soft contact lenses you may be familiar with in that it is somewhat larger, hard, and must be filled with special fluid before being placed on the eye. Even though it is made of a rigid material, it is actually quite comfortable, owing to the fact that it does not touch the sensitive cornea and constantly hydrates the front of the eye with the tear-like fluid that it is filled with. These features are the basis of why your optometrist may recommend scleral lenses to you. 

 

Uses of Scleral Lenses

One of the primary needs for a scleral lens, or any rigid lens, is to improve vision when the cornea becomes irregular and no longer transmits a clear image to the back of the eye. This can occur for several reasons: conditions such as keratoconus where the cornea thins and becomes pointed, after a surgery to the eye where the tissue is changed in some way that does not enable proper vision, or after severe injury to the cornea, again causing its structure to weaken and shape to change. If you have severe dry eye disease that is not solved by other treatments, your eye doctor may recommend scleral lenses as a way to protect the eyes from feeling dry and painful. 

 

How to Use a Scleral Contact Lens

Scleral lenses are different from other contact lenses in that they completely vault over the cornea and must therefore be filled with fluid to keep them in contact with the eye. Before the lens is put onto the eye, it must be filled to almost overflowing with unpreserved saline solution. While the wearer keeps their face parallel to the ground, the lens is raised to the eye. If it is not applied properly, a bubble will form and the lens must be removed, filled with fluid, and put on again. For removal, a plunger can be used or the eyelid can be moved underneath the lens to break suction and remove it. Like any other contact lenses that are repeatedly used, scleral lenses must be cleaned regularly by rubbing and rinsing with special cleaning solution and never with tap water. They must also be stored in disinfectant solution overnight. 

 

Our eye doctors at Eye Theory in Houston, TX excel in the prescription of contact lenses, glasses and various eye diseases.  Call our optometrist at 832.831.7386 or schedule an appointment online if you would like to learn more about scleral lenses.  Our eye doctor, Dr. Jonathan Tsao, provides the highest quality optometry services  and eye exams in the Midtown and Southside Commons (Southside Place) vicinities of Houston, Texas.

Choosing the Right Lens Options for Your New Glasses

There are many materials, designs, coatings, and treatment options to consider when you are choosing lenses to go in your newest pair of glasses.  These seemingly simple decisions can have a huge impact on your satisfaction with your lenses.  At Eye Theory, our experienced opticians can help you navigate the overwhelming task of choosing new lenses.  We have also compiled a quick reference guide to help answer some frequently asked questions about lenses. 

 

What Lens Material Should I Choose for Glasses?

The material used to make your lenses can impact the optics and clarity of your vision.  One of the most commonly used materials is CR-39, a lightweight and cost-effective plastic material that delivers good optics and clear vision.  While CR-39 is a strong lens, it does not include any additional coatings or special properties.  Another popular lens choice is polycarbonate lenses.  Polycarbonate is a durable, shatter-resistant material.  Its protective properties make it ideal for children, and it also provides some UV protection.  For people with strong prescriptions who want to avoid thick lenses, a high index material should be considered.  High index lenses help reduce the thickness and weight of lenses, which makes them more comfortable and cosmetically appealing.  

 

What Lens Coatings Should I Consider?

After you decide on a lens material, you need to decide on any additional lens coatings or treatments that you need to make your lenses suit your needs.  The most popular option is an anti-reflective coating.  This special treatment reduces reflections from both the front and back surface of your lenses and helps to reduce glare and improve visual comfort.  If you are bothered by glare from overhead lights, oncoming headlights, or long hours at the computer, this coating should be considered.  It also helps improve the cosmetic appearance of lenses and makes your lenses less noticeable.  You may consider treatments such as scratch-resistant coatings or UV-blocking coatings, though many lens materials, such as polycarbonate lenses, already include these properties.  Another popular lens option is photochromatic treatment.  Photochromatic lenses are clear lenses that transition into tinted sunglass lenses when exposed to UV light.  Photochromatic lenses are a cost-effective way to avoid buying both regular glasses and prescription sunglasses.  Though they are great for efficiency, photochromatic lenses have some drawbacks.  In certain conditions, they can be slow to change back into a clear lens after coming inside on a sunny day, leaving you with tinted lenses for longer than desired.  Additionally, because car windows and windshields are designed to block UV rays, most photochromatic lenses will not work in a car.   If you are more interested in a pair of prescription sunglasses for your outdoor needs, you can choose to have polarized lenses.  This treatment is used in sunglasses to filter out horizontal reflecting rays.   This can significantly reduce glare and improve clarity, and many outdoorsmen favor this lens coating.  

A highly trained optician is invaluable when it comes to choosing lenses.  By learning about how you use your eyes, including your job, your hobbies, and your type of prescription, they can help make tailored recommendations so you are satisfied with your glasses.  

 

Our eye doctors at Eye Theory in Houston, TX excel in the prescription of contact lenses, glasses and various eye diseases.  Call our optometrist at 832.831.7386 or schedule an appointment online if you would like to learn more about lens.  Our eye doctor, Dr. Jonathan Tsao, provides the highest quality optometry services  and eye exams in the Midtown and Southside Commons (Southside Place) vicinities of Houston, Texas.

 

Why Do I Have Floaters and Flashing Lights in My Vision?

Many people experience strange visual phenomena such as flashes of light or strange “floaters” in their vision.  These visual experiences can be alarming and confusing, especially the first time they are noticed. In most cases, these symptoms are indicative of a normal aging process occurring within the eye.  However, occasionally they can be a sign of a more serious condition affecting the retina.  If you notice these symptoms, you should talk to your optometrist.  Continue reading to learn more about these symptoms and what they mean.  

 

Floaters

“Floaters” is the term that eye care professionals use to describe dark spots or strands that drift through vision.  Some people describe floaters as seeing bugs or cobwebs float in front of them.  In reality, floaters are the result of changes occurring within the eye.  The inside of the eye is filled with a gel-like structure called the vitreous, which plays an important role in giving the eye shape and structure.  When we are young, the vitreous is a thick gel, almost the consistency of gelatin; however, it slowly begins to liquefy over time.  Sometimes clumps of gel will remain as the rest of the vitreous becomes increasingly watery.  These clumps will cast shadows on the back of the eye, and we perceive them as floaters.  While floaters can be distracting or annoying, they are generally harmless and do not require any treatment.  Most people find that floaters become less noticeable over time.  

 

Flashing Lights and Vitreous Detachments

Noticing flashes of light can be another sign of common changes affecting the vitreous. These flashes of light will typically occur in the periphery, and they might appear like a bolt of lightning or a flashing camera.  Flashes are caused by traction between the vitreous and the retina.  The vitreous is lightly attached to several areas of the retina, but when the gel slowly begins to liquefy, it pulls away from the retina and creates areas of tension.  This stimulates the cells inside the retina which detect light, so the brain perceives a bright flash.  This process is called a posterior vitreous detachment, or a PVD.  Flashes of light can be noticed sporadically throughout a PVD, and they should decrease in frequency as the vitreous eventually becomes completely unattached from the retina.  It is relatively common to experience the symptoms of a PVD, and the process is increasingly likely with old age.  

 

Risks of Flashes and Floaters

Symptoms such as floaters and flashes occur in many people, and most of the time they are benign findings.  However, a PVD can carry some risks involving the retina.  During a PVD, there is a very small chance that the traction between the vitreous and the retinal tissue can result in a tear to the retina.  If left untreated this can cause serious complications, such as a retinal detachment.  Symptoms such as an increase in flashes or floaters, or the perception of a curtain or veil over your vision should always be evaluated by your eye doctor.  The doctor can dilate your eyes to assess the retina and make sure there are no risks to your vision. 

 

Our eye doctors at Eye Theory in Houston, TX excel in the prescription of contact lenses, glasses and various eye diseases.  Call our optometrist at 832.831.7386 or schedule an appointment online if you would like to learn more about flashes (ie: flashing lights) and floaters in your vision.  Our eye doctor, Dr. Jonathan Tsao, provides the highest quality optometry services  and eye exams in the Midtown and Southside Commons (Southside Place) vicinities of Houston, Texas.