Lasik is a procedure which rectifies refractive errors (like myopia, hypermetropia, astigmatism) with the use of excimer laser which thereby reduces the dependency on glasses or contact lenses.
Normal Vision: In a person with normal eyesight, the light rays pass through the cornea, pupil, lens and focus directly on the retina (inner layer of the eye) resulting in clear near and distance vision.
Refractive error is an imperfection of vision where the rays of light do not fall on the retina.
Refractive error may be classified as follows:
Myopia (Minus number/ short sight) : In myopia, rays of light focus in front of the retina instead of focusing on the retina. Due to this defect, a person has difficulty in seeing distant objects and can see near objects clearly.
Hypermetropia (Plus number / Long sight) : In hypermetropia, rays of light focus behind the retina instead of focusing on the retina. Due to this defect a person has difficulty in seeing near objects and distant objects can be seen clearly.
Astigmatism : In astigmatism, light rays are focused at different points on the retina, thus distorting the image and resulting in a blurred/ distorted image.
To overcome these deficiencies, glasses were invented in the 13th century. Now a day’s contact lenses are more popular but they can only hide glasses, not cure the problem. In late 1970, a surgical procedure known as radial keratotomy was invented to correct moderate amount of myopia. During the course of time other technique also developed. They did not become popular due to recurrence of refractive error and accuracy. Recently the use of laser to rectify refractive error has become popular. LASIK today has scaled the height of safety precision and accuracy and has become the fastest developing science in the world of ophthalmology to improve the focusing power of the eye.
LASIK – Procedure
The cornea is clear crystal dome that convers the front of the eye. The cornea accomplishes majority (70%) of the bending light rays. It is this tissue of the eye which is treated with laser to correct the refractive errors and eliminate the dependence on glasses or contact lenses.
The procedure uses a computer controlled “Excimer Laser” to shape the cornea to correct the refractive error.
The excimer laser is an ultraviolet laser and utilizes gas (Argon and Fluorine) to create a non-thermal cool beam of laser light.
Procedure takes place as follows :
Anaesthetic drops are put to numb the cornea, NO INJECTION OF ANY SORT ARE GIVEN AND NO PAIN IS FELT. Although some discomfort may be felt during the procedure depending upon the individual tolerance level of the patient.
A ring is placed on the eye and pressure is applied to create suction. As the suction ring is on, vision becomes dim and a slight discomfort is felt. Then with a microkeratome a corneal flap is cut. Then with a microkerstome and suction ring are then removed.
The flap is then lifted and folded back on the hinge and the exposed tissue is dried. The laser beam is then focused and patient is asked to stare at a particular red light. This light helps to keep the eye steady on one spot.
The pulse pf laser makes a ticking sound, a computer controls the amount of laser energy delivered to the patient’s eye. According to the calculated measurements, laser is used to decrease / increase the cornea’s refractive curvature. Then the corneal flap is repositioned back.
Due to cornea’s extra ordinary internal bonding quality, no stiches/ sutures are required. Even eye patch is not required.
LASIK is an in-office procedure where patient can go home within half hour after doing the procedure. The procedure takes only about 15-20 minutes and both eyes are done on the same day one after another.
Results indicate that vision stabilizes in 2 weeks of doing the procedure and one can get back to work within 2-3 days of treatment.
Are you eligible for LASIK?
- Patient should be above the age 18 years.
- Hormonal levels should not be fluctuating (Diabetes, pregnancy)
- Refractive error should stable for 6 months
- Lasik technique can correct myopia upto 18.0D, hypermetropia from +1.0D to 6.0D and astigmatism from -1.0 D to 6.0D.
Besides the routine eye examination some pre operative tests need to be done i.e
Keratometry – To evaluate the shape of the cornea
Pachymetry – To measure the thickness of the cornea.
Do’s And Don’ts
Before the surgery
- IF you are wearing soft contact lens you need to discontinue wear for at least 48 -72 hours
- If you are wearing RGP lenses discontinue wear for 15 days
On the day of surgery
- Wash your hair
- No eye cosmetics to be applied
- Do not wear cream, lotions, perfumes, deodorant etc.
After the surgery
- Wear sunglasses upto 1 week
- No splashing of water directly into the eye for around 1 month
- No head bath for 1 week
- No swimming for 1 month.