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Astigmatism

What is Astigmatism?

Astigmatism is an imperfection in the curvature of your cornea — the clear, round dome covering the eye's iris and pupil. Abnormal curvature of the cornea which can result in abnormal focusing of light and impaired vision.

Astigmatism Part 1

The Normal Eye

In a normal eye, the cornea and lens focus light rays on the retina.

   

Astigmatism Part 2

  

In astigmatism, images focus in front of and beyond the retina, causing both close and distant objects to appear blurry.

Astigmatism is very common. In most cases, people with astigmatism are born with this condition. The reason why corneal shape differs from person to person is unknown, but the likelihood of developing astigmatism is inherited.

  

Sometimes, astigmatism can develop after significant eye disease, eye injury or surgery. It is a myth that astigmatism can develop or worsen from reading in low light or sitting very close to the television.


Soft contact lenses, including those made to correct astigmatism, usually do not cause any change in the astigmatism of an eye. Rigid contact lenses may occasionally mold the cornea (the clear front window of the eye) with a resulting change (usually a reduction) in astigmatism, but this molding is not permanent, and the eye usually returns to its original state if contact lens wear is discontinued.

Symptoms

Astigmatism symptoms may include blurry vision or areas of distorted vision, eyestrain, headaches, squinting to try to see clearly or eye discomfort.

Diagnosis

Your Palm Beach Eye Center (PBEC) ophthalmologist will perform a comprehensive eye exam, and will use various instruments to measure how your eye focuses light.


Corneal astigmatism power and axis can be measured in many different ways, including the following:

· Keratometry: Manual Keratometer, Automated Keratometer, IOL Master

· Corneal Topography

Non Surgical Treatments

Soft contact lenses called toric contact lenses can correct astigmatism. But while soft toric lenses may be appropriate for the correction of mild to moderate astigmatism, if you have severe astigmatism, rigid contacts or glasses may be a better option. Your PBEC ophthalmologist will discuss your lens options with you.


Surgical Treatments

For some people with astigmatism, surgery may be an option to correct vision. Your PBEC ophthalmologist can discuss the various types of refractive surgery procedures you may consider for astigmatism correction.

Your PBEC ophthalmologist has several methods of correcting astigmatism for those who want to maximize their vision without the need for glasses or contact lenses.

1. LASIK or PRK

LASIK or PRK is not indicated in patients who require cataract surgery.


2. Limbal relaxing incisions (LRI) / Astigmatic Keratometry (AK) can be performed at the time of cataract surgery to eliminate or reduce astigmatism. LRIs are very small, but very deep, extra incisions that are placed in the corneal periphery at the exact clock hour of the astigmatism in the cornea. Because LRIs are typically made by hand and because each person heals differently, LRI results can vary.


Astigmatic keratomy / limbal relaxing incisions may be performed either in conjunction with cataract surgery or, if there is remaining astigmatism, after the procedure.

                   

Femtosecond Lasers have now been incorporated into traditional cataract surgery. The laser creates the LRIs/AKs at the time of the procedure as well. Precision and uniformity of the location, depth and length of the incisions are vastly superior with this technology. Your PBEC ophthalmologists have had extensive experience with the Femtosecond Laser in cataract surgery for the past 3 yrs. with outstanding results.

Ask your PBEC ophthalmologist about the technologically advanced Femtosecond Laser for your cataract operation.


3. Toric Intraocular Lenses (IOLs) refer to astigmatism correcting intraocular lenses used at the time of cataract surgery to decrease post-operative astigmatism.


A toric intraocular lens (IOL) is a modification of a standard intraocular lens that has the needed astigmatism correction built into the lens. It must be ordered  specifically for the degree of astigmatism to be corrected. The lens is implanted inside the eye during routine cataract surgery in a very exact orientation so as to line up the corrective power of the lens in the exact clock hour needed to correct the astigmatism. Toric IOLs do an outstanding job at correcting astigmatism and allowing the patient to be less dependent on spectacles.

Accurate determination of the amount of astigmatism is paramount. Your PBEC ophthalmologist has at his/her disposal the most advanced diagnostic technology available.


Your PBEC ophthalmologist will determine which toric IOL is best suited for your visual needs. 


Current Research Indicates that Toric Lens Implants are superior to cutting procedures.


This randomized study found that toric IOLs were more predictable and effective in reducing astigmatism than limbal relaxing incisions (LRIs).

Toric IOL eyes had less postop astigmatism: 90 percent had < 1 D in the toric group compared with 40 percent in LRI group. Also, the LRI group had significant regression of effect over the first six months (about 0.4D). Interpatient deviation in postop astigmatism was smaller with toric IOLs, making them more predictable.

These results suggest that toric IOLs are better at lowering astigmatism than manual LRIs, although it would be interesting to see a similar study done using a femtosecond laser to perform the LRIs.

"Correction of moderate corneal astigmatism during cataract surgery: Toric intraocular lens versus peripheral corneal relaxing incisions": JCRS March 2014Volume 40, Issue 3, Pages 354–361


The information presented here was written by Peter Pearlman MD who regularly performs astigmatism reduction surgery.

Astigmatism Part 3 - Surgical Options

AcrySof Toric IOL (Alcon Labs, Fort Worth, Tx)

Staar Toric IOL (Staar Surgical, Monrovia, Ca

AMO Tecnis Toric IOL (Abbott Medical Optics, Inc, Santa Ana, CA)

Trulign Toric IOL (Bausch + Lomb, Bridgewater, N.J.

What are my surgical options?

The physicians at Palm Beach Eye Center perform astigmatism removal procedures all the time.  Lasik and PRK are also options we commonly employ.

Limbal Relaxing Incisions

Words From the Medical Director

All of our physicians have performed astigmatism reducing surgery from hundreds to thousands of cases.  I have 17 years of experience in reducing astigmatism.   I first like to measure the cornea with devices we have in the office to determine if there is a regular pattern to the astigmatism or irregular.  This is very important to determine which treatment to use and which will be the best.  


The second objective is to determine if the patient has a cataract or not.  If there is a goal to remove the astigmatism and there is a moderate amount of cataract, performing a Lasik or PRK can be done but the patient will end up having cataract surgery in the future and this option is not the best.


If the patient is young, let's say less than 50, I usually advocate a LASIK or PRK procedure.  They're fast, and easy and almost always have amazing results.  We can treat up to about 3 units of astigmatism with this safely with a low rate of reoccurrence.  With higher levels I tend not to recommend this for a surgery option.  The outcomes are variable.


If the patient has a cataract, then I will determine how much astigmatism the patient has.  Generally, I can successfully treat up to 6 units of astigmatism very easily with one of the implants see in the pictures above.  

Frequently Asked Questions (FAQ's)

Will it come back?


With cutting procedures like the LRI or AK, it is more likely to come back than with LASIK or PRK.  With lens implants almost always remains stable


How much astigmatism can you fix during cataract surgery?


I'm very comfortable removing up to 5 units of astigmatism with excellent success.  I have removed 7 units by combining an LRI with an Alcon Toric Lens.  The outcome was fantastic.  7 units is really rare.


How do I know if I have astigmatism?


Most people don't until they are told they have it by an eye doctor.  Glasses will always be made to correct it if you have more than a certain amount.


Can astigmatism harm me?


It doesn't harm a person, but it surely can make things blurry if its not corrected.  It can also cause headaches and tension around the eyes.  Treating too much of it when a patient is ready, can also cause strain, and headaches.  Google the word Asthenopia.  Very commonly occurs with astigmatism.


Are there any other benefits to treating astigmatism besides improved vision?


A lot of patients have better depth perception and reaction time when driving.  

There is also a sense of equilibrium that patients will describe after its treated...They'll often say I just feel better.  All these are common.


What if the astigmatism is treated wrongly?


Many patient's have come to me for second opinions when not seeing properly, or their surgery meeting their expectations.  A lot of times the lens implant rotated inside the eye.  Other times the astigmatism treatment is reversing.  This can occur and generally we have great and easy fixes for this.  


My astigmatism is getting worse and worse, what's wrong doc?


This is the most common question I get.  The possibilities include the astigmatism worsening naturally meaning its nomal, but often patients will get warpage of the cornea from improper contact lens fitting or wear.  A major problem can be conditions called Keratoconus and Pellucid Marginal Degeneration.  These can be serious corneal conditions and should your astigmatism worsen come and let us test you for this.  It can be treated but treating late is never the ideal situation.