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Refractive error correction Laser surgery
Advances in science and technology have brought significant benefits to several areas of medical care, including the treatment of eye diseases. Among other technologies, Lasers have been particularly useful in eye care, where they are used to correct refractive errors, minimizing or eliminating the need for glasses or contact lenses. Ophthalmologists at L V Prasad Eye Institute (LVPEI) have the expertise and experience in Laser Surgery, and have gained an international reputation as leaders in this clinical practice. They have been providing laser refractive surgeries for many years with extremely successful outcomes.
The new generation 'vision correction procedure'
In early 2003, LVPEI added the 'Wavefront assisted customised vision correction technology' to the list of corneal services. This new technology scores over other procedures for vision correction in a number of ways. It can not only correct the more common vision defects such as Myopia and Astigmatism (Cylindrical Vision), but is a customized technique that measures and corrects even minute aberrations unique to that particular eye, giving results that were, until now, never considered possible.
What are refractive errors?
The eye functions like a camera. Light rays entering the eye are focused by the cornea and the lens of the eye onto the light sensitive retina, the film, at the back of the eye. The retina transmits a clear image, or photo, to the brain. In a patient with refractive error, the light rays fail to get focused on the retina and blurred images are formed and as measured as aberration patterns.
What is LASIK?
LASIK is short for 'Laser Assisted in Situ Keratomileusis'. This technique involves raising a partial corneal flap surgically using an automated microkeratome, ablation of the stromal bed with laser and repositioning of the flap. Ablation is performed using excimer laser beams which can cut and slice the tissue in a highly precise manner and then can change the custom of cornea making it better or steeper.
What is Wavefront Assisted Customised
Lasik?
In this procedure, not only are the refractive errors corrected, but even the minutest of aberrations (called as higher order aberrations) in the optical system of the eye are removed thus resulting in a much improved quality of vision. The aberrations are detected by an instrument called the aberrometer (Zywave) and then both the refractive error and higher order aberration details are fed in the Laser machine. The Laser machine then ablates the cornea in a way that these defects are removed.
The Zyoptix procedure leads to more accurate vision correction, better night vision, greater predictability of the surgical outcome, reduced glare, enhanced contrast sensitivity, greater safety and efficacy.
Different defects or aberrations that can be corrected
Myopia or shortsightedness occurs when light rays are focused in front of the retina causing blurred vision, particularly when viewing distant objects. Objects that are near may be seen clearly. Myopia is often hereditary; most often it is due to abnormally large eyeball or steeply curved cornea. Because the eyeball grows with age, Myopia tends to progress, usually stabilizing by the time you are 20 years old.
Hyperopia or farsightedness is the opposite condition, where the light rays converge at a point beyond the retina. Initially objects that are near seem blurred and distant vision is clear. However, with age, objects at all distances become blurred.
Astigmatism is an irregularity in the shape of the normally spherical cornea. The cornea is shaped like an egg or the back of a spoon, causing distortion of both distance and near vision.
Who can undergo a laser correction procedure?
- You must be above 18 years old.
- You should not have had a significant change in your spectacle prescription for the past 12 months.
- You should not have any ocular surface abnormality such as Dry eye.
- You should have adequate corneal thickness
Patients with superficial corneal opacities can also be treated with laser to remove these opacities. This procedure is known as photo therapeutic keratectomy or
PTK.
Why would you be interested in Laser surgery?
- You do not want to wear spectacles or contact lenses!
- You feel visually and socially restricted by spectacles or contact lenses
- You are intolerant to contact lenses
- You want to participate in certain outdoor sports where using spectacles or contact lenses may be a problem
- You plan to join certain professions wherein excellent uncorrected visual acuity is a prerequisite.
What happens before the Laser procedure?
The patient goes through a normal eye examination after which the ophthalmologist may suggest a vision corrective procedure. Thereafter, information about the patient's eye structure and function - including corneal thickness, corneal curvature, optical aberrations etc., will be corrected. All this will be done with the help of state-of-the-art diagnostic equipment. The eye test reports are studied by the ophthalmologist to make a final decision.
What to expect when you go in for Laser surgery?
At LVPEI Laser surgery is done on an out-patient basis; this means you go home immediately after surgery. A relative or friend who can take you home after the surgery should accompany you. Usually, one eye is treated at a time and this procedure is done under topical anesthesia.
You will be made to lie down on a couch and asked to look up at the microscope where you will see a blinking green light. When the suction ring is applied, your vision will fade out. You will start seeing light again after the suction ring is removed. The whole procedure will be over in a few minutes. Usually no pain is felt during the procedure.
After Laser Surgery…
Immediately after the surgery your eye will be covered with a shield after the administration of some drops and ointment. You can return home immediately. You may experience pain for the first 24 to 36 hours, for which you will have to take oral analgesics. You will have to come for follow up visits from the very next day. Your counselor will schedule the necessary check ups after the surgery.
- The first check up will be in the morning after the surgery
- After 7 days from the date of the surgery
- After 1 month from the date of the surgery
- After 3 months from the date of the surgery
- After 12 months from the date of the surgery
You will undergo special diagnostic tests at each visit to the institute, to assess your visual acuity. It is important that you report to your doctor on each of these appointments. You will be advised to use eye drops or other medication during the postoperative period.
How soon will you see the result?
Your vision becomes clear within a few days. Sometimes you may require another round of treatment with laser, particularly with higher degrees of refractive error.
Possible side effects
Laser surgery is very safe and effective. But in some patients there could be side effects. Your doctor will be happy to discuss these with you and clear your doubts before surgery.
Undercorrection/Overcorrection: Undercorrection may sometimes be planned intentionally or may occur as an unintentional effect. As a result, the eye remains short sighted even after the surgery. If the degree of residual myopia is significant, then the eye may be re-treated at a later date. Overcorrection may occur very rarely.
Glare/halo effect: You may feel some sensitivity to light at night or in bright sunlight. Sometimes in dim light, you may see a faded ghost image around the sharp bright image. This will pass after the first few days or weeks.
Decrease in contrast sensitivity: Some people may experience that their night time vision has become a bit dull. It happens because of decrease in their ability to discriminate between different contrast levels.
Flap complications: Sometimes the anterior corneal flap that is made in LASIK may not be complete if the keratome stops mid way because of suction loss. In this situation the flap is repositioned and ablation is deferred and surgery is re-attempted after 3 months. In rare instances, the flap may tear or become detached.
Corneal ecstasia can occur if corneal thickness is less to begin with or cornea is thinned with laser more than it can withstand. Therefore, people having inadequate corneal thicknes are not suitable candidates for
Lasik.
Other complications:
Serious complications like corneal infections, corneal edema, corneal perforation etc., though possible, are extremely rare.
Important!!
Although Lasik is an excellent procedure for low and moderate refractive errors, it may not totally remove the needof using glasses in everybody. However, it definitely decreases the dependence on glasses for day to day work.
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