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Astigmatism and LRI

Corneal Astigmatism


astigmatism-correction

Whether myopic or hyperopic, most eyes have corneal astigmatism to some degree. Corneal astigmatism means that the front part of your eye, the clear window you look through, is not perfectly round. Instead of being spherical like a basketball, an astigmatic cornea is slightly flattened, more oval in shape like a football, with one side steeper than the other (as illustrated above).

Because the astigmatic cornea is curved more (steeper) in one direction than the other, light entering the eye is refracted differently as it passes through these different areas. This causes light to come into focus at several different points on the back of the eye, rather than ideally coming into focus at just one point.

Depending on the direction and the amount of astigmatism, vision through an astigmatic cornea will be affected in various ways. The illustration (below) gives a broad example of the visual effects, depending on the overall direction of the curve:

astignmatism

Limbal Relaxing Incisions For The Correction of Astigmatism

It is most common for eye surgeons to simply prescribe glasses or contact lenses for the correction of astigmatism after cataract surgery. Some surgeons will treat corneal astigmatism at the time of cataract surgery by placing "limbal relaxing incisions" (LRI's). This involves making tiny incisions in the cornea to "relax" or flatten the steeper meridian, thereby causing the corneal curvature to become more rounded, reducing astigmatism.

These long, thin incisions are placed at the very edge of the cornea (known as the corneal limbus) on the steepest meridian, and differ in number and length according to the amount of astigmatism. Relaxing incisions generally do not eliminate corneal astigmatism completely, but rather reduce it to an acceptable level. Because the cornea is living tissue, there may be "over-response" or "under-response" to these incisions. Seldom is corneal astigmatism completely resolved; however, a significant reduction in your astigmatism produces a more satisfactory uncorrected visual result.

LRI-incisions

Some patients with extreme amounts of astigmatism may still require the addition of limbal relaxing incisions to correct astigmatism after cataract surgery with the AcrySof toric lens. For the patients, with unusually high amounts of astigmatism, implanting the toric lens means that less corneal surgery in the form of a limbal relaxing incision is needed to achieve the same amount of correction.

In the future, the AcrySof Toric Lens will be available in higher powers of astigmatic correction so that for very high amounts of corneal astigmatism can be corrected without the need for the addition of limbal relaxing incisions.

 
Eye Care Associates of Denton

Eye Care Associates of Denton
3311 Unicorn Lake Blvd., Suite
181. Denton, TX 76210
(940) 323-2020 Main Number
(940) 323-2011 Fax Number

Doctor Description
Doctor Nadeem Haq
 
Dr. Haq's Bio
 
Office Hours
Monday - Friday
8:00am to 12:00pm
1:00pm to 5:00pm
 
Closed on Saturday and Sunday