Cosmoscience Jun.2014 | Page 6

LASER EYE

SURGERY

“Two things are infinite: the universe and human stupidity; and I'm not sure about the universe.”-Albert Einstein

Laser eye surgery is the use of a focused beam of light, a laser, to cut eye tissue for the correction of disorders. This surgery is mostly used to correct Long-sightedness and Short-sightedness. These problems are caused by the shape of the cornea, which laser eye surgery aims to change, in order to correct the problem. In Short-Sighted people, the cornea bends the light too much, because it has a higher than normal index of refraction.This is because the cornea is more curvy than normal. This makes the light bend too much as it goes from the air to the eyes, therefore causing the image to form in front of the retina as the light converges there, instead of forming at the retina. In other words, the images focal point is formed in front of the retina. This then creates a blurred image of objects farther away. Laser eye surgery corrects this problem by using a laser to burn away small amounts of the cornea, as the laser light converts to heat when it hits the eye. This flattens the cornea therefore giving it a lower index of refraction. This then means that the incoming light won't bend as much, thereforefocusing the image closer to the retina than before as the light converges closer to the retina.

In Long-Sighted people, the refractive index of the cornea is lower than normal. The cornea and the lens do not bend the light enough to converge it at the retina, which cause the image’s focal point to be

behind the retina. The surgeon uses laser to correct this by removing the outer edge of the cornea thus steepening it. This increases the index of refraction and makes light bend a bit more when it enters the cornea. The eye is able to focus the image directly on the retina.

Laser eye surgery is one of the fastest methods to correct visual impairments. It has the ability to correct even severe refractive errors, but minimize the recovery time. Most patients are able to return to work within a week! Many patients even return to normal activities the day after surgery. The treatment is permanent according to studies done so far, but as eyes change with age re-treatment may be necessary over time. Eye drop medication is necessary for the first week, but discomfort wears off after 5-6 hours. The medication is used to prevent infection, not as a pain suppressant. The main disadvantage of LASIK surgery is that it requires the creation of a flap in the cornea. This step takes less than a minute to complete, but there are risks of complications.

Everyone’s eyes are different. A pre-procedure consultation with your doctor will help determine the right type of laser eye surgery for you.