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Home Blog Is LASIK or Refractive Surgery an Option For Me?

Is LASIK or Refractive Surgery an Option For Me?

Posted on by Eye Theory

Refractive Surgery

Are you tired of wearing glasses or contacts and considering corrective surgery? This article will briefly discuss the different options and how corrective surgery works!

Anatomy of the Eye

To understand how corrective surgery works, a basic understanding of the eye’s anatomy will be beneficial.

The eye has 3 major parts to it—the cornea, the lens, and the retina.

The cornea is the front structure of your eye. It is clear and overlays the pupil and colored part of the eye (iris). It consists of 5 layers—from the most outside layer to inside layer: epithelium, Bowman’s layer, Stroma, Descemet’s membrane, and the endothelium.

The lens is the middle part of the eye. It is a flexible structure that can change shape based on where you want to focus—far away or up close.

The retina is the very back of the eye. It is responsible for actually detecting light and transmitting it to the brain to form images.

Light has to be able to pass easily and undeviated through the cornea and lens to land properly on the retina. If the cornea and/or lens are misshaped, the light will not focus correctly on the retina and vision will appear blurry—hence the need for glasses or contact lenses.

 

How Does Refractive Surgery Work?

Refractive surgery works by a surgeon (ophthalmologist) restructuring your cornea. This can be accomplished a few different ways, but ultimately the surgeon will use a laser to cut and remove part of your cornea to make its’ shape optimal for your refractive error.

If you are farsighted (i.e. hyperopic) the surgeon will want to steepen the central part of your cornea, this can be accomplished by flattening (i.e. removing part of) the outer edges of your cornea.

If you are nearsighted (i.e. myopia) the surgeon will want to flatten (i.e. remove part of) the central portion of your cornea.

 

Am I a Candidate for Refractive Surgery?

There are many aspects of your eyes that must be considered prior to deciding if you are a candidate for refractive surgery.

Your cornea needs to be a certain thickness to allow the surgeon to manipulate the tissue without making it too thin.

You need to have a stable prescription—once you undergo refractive surgery it is much more difficult to perform a second surgery.

You must be at least over the age of 18 years old.

Your prescription must fall within certain parameters—parameters very upon different techniques.

Your eyes must be healthy and free of inflammation. Certain ocular diseases will disqualify you from this procedure.

Your eye doctor will evaluate you closely and weigh the pros and cons of the procedure.

 

Different Types of Refractive Surgery

There are three major types of refractive surgery to date. Over the years these techniques have been improved and perfected, whereas others have been discontinued due to complications.

 

PRK

PRK, or Photorefractive Keratectomy, is a procedure in which the cornea epithelium and Bowman’s membrane are removed with a laser, and the stroma is “shaved down” to create the optimal surface to correct for your prescription.

PRK has a longer post-operative recovery time (about 2 weeks) since the epithelium will need to regrow completely.

PRK is recommended for individuals who live especially active lifestyles or are in the military.

 

LASIK

LASIK, or Laser-Assisted In Situ Keratomileusis, is also a procedure in which a laser is used to correct a patient’s vision by reshaping the cornea.

LASIK differs from PRK in the fact that a laser is used to create an epithelium and bowman’s layer “flap”. The surgeon lifts the flap to access the stroma and “shave it down” to create the optimal surface to correct for your prescription.

Since LASIK does not actually remove the epithelium and Bowman’s layer, it has a quicker recovery time of around 24 hours.

 

SMILE

SMILE, or Small Incision Lenticule Extraction surgery, is the newest form of refractive surgery.

SMILE creates a very small incision—no flap is created. The epithelium and Bowman’s layer remain in tact and the stroma is shaved down to reshape the cornea to the optimal shape to correct for your prescription.

 

Common Questions About Refractive Surgery

Can I get refractive surgery if I am farsighted (hyperopic)? Yes! In the past hyperopes may have been excluded, but today techniques have improved greatly to include our hyperope friends as well.

Can I get refractive surgery if I have astigmatism? Yes! It’s a bit more complicated, and there is a limit to how much can be corrected, but astigmatism does NOT exclude you from refractive surgery.

Is it true that if I get refractive surgery I’ll never need glasses again? No! While the majority of people post-surgery will not require correction, a select few number of patients will still require glasses post-opt. Also, you will still need reading glasses with age as cataracts/the need for reading glasses are an issue with the lens, not the cornea. So, almost everyone will need glasses eventually (typically decades down the road) post-opt.

Is it true that I will be awake during surgery? Yes. You will be given a topical numbing drop so you will not feel anything, but you will be asked to stare at a target for a few seconds. The laser system will tract your eyes so that if you move slightly the system will shut down until proper focus is regained—this prevents the surgery from continuing in case of needing to sneeze or another reason in which focus is lost.

Since a laser is being applied to my eye, does the surgery burn? No! You won’t feel much of anything. The laser is perfectly focused so that it cannot hurt anything besides just reshaping your cornea.

After surgery I won’t need to see my eye doctor yearly, right? Wrong. You will need a few follow-ups with your eye doctor after the surgery, and then it is recommended that you continue to see your eye doctor yearly. Refractive surgery has the tendency to cause an increase in dry eye symptoms, which your eye doctor will be able to help you manage, if needed.

It is also very important to continue to have yearly eye exams to check the health of your eyes as your cornea is being altered during surgery and complications (while uncommon) do occur. The sooner these complications are caught, the better off the prognosis.

 

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 LASIK and the types of refractive surgery.  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.

Home Blog Why You Should Try Multifocal Contact Lenses

Why You Should Try Multifocal Contact Lenses

Posted on by Eye Theory

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.

Home Blog Understanding Your Glasses Prescription

Understanding Your Glasses Prescription

Posted on by Eye Theory

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.

Home Blog Why are there Floaters in My Vision?

Why are there Floaters in My Vision?

Posted on by Eye Theory

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.