LASIK, short for Laser Assisted in Situ Keratomileusis, is a surgical procedure to replace glasses that uses a cool (non-thermal) beam of light to gently reshape the cornea— the clear covering of the front of the eye, using an excimer laser to improve vision. It is a two-step procedure which begins with a hinged flap creation using a mechanical microkeratome (a blade device) or a laser keratome (a laser device). The laser removes microscopic bits of tissue to flatten the cornea (for nearsightedness or myopia), steepen the cornea (for farsightedness or hyperopia), and/or smooth out the corneal irregularities (for astigmatism). In most cases, the thickness of the layer of corneal tissue removed by the laser is less than the thickness of a human hair.
Lasik is now considered “the safest and most accurate method to correct various corneal disorders”. It is an established and proven procedure for vision correction in USA and European countries since 1990. The most important thing about the operation is that it enables a person to escape the burden of glasses and contact lenses.
LASIK surgery cannot treat presbyopia (lau hua) per se. However, monovision through LASIK is a popular option. In monovision, one eye is fully corrected for distance vision whilst the other eye for reading, is under-corrected with residual myopia, in order to offset presbyopia.
Who can have Lasik?
Any individual above 18 years of age, have had a stable vision for the last 6 months, is not pregnant, is free of certain diseases of the cornea and retina and is generally in good health. However Lasik can correct the following powers:
Nearsighted ( Myopia ) : -1.00 to -14.00 Diopters Farsighted ( Hyperopia ) : +1.00 to + 7.00 Diopters Astigmatism : 1.00 to 7.00 Diopters
How Lasik Is done?
The Pre-Lasik Test:
Before having LASIK, you’ll need a complete eye examination (Pre-LASIK Test) to determine the fitness for the procedure. Take your eye prescription records with you to the exams. Your doctor will
- Dilate your pupils to fine-tune your prescription
- Examine your eyes to make sure they’re healthy. This includes a glaucoma test and a retina exam
- Take the following measurements:
- a)The curvature of your cornea and the size of your pupils
- b) The topography of your eyes to make sure you do not have an irregular astigmatism or a cone-shaped cornea — a condition called Keratoconus
- c) The pachymetry — or thickness of your cornea. You need to have enough tissue left after your corneas have been reshaped
Before coming for Pre-LASIK tests a contact lens wearer must stop wearing lenses at least for three days earlier.
If you qualify for surgery, your doctor may tell you to stop wearing your contact lenses for a while before the surgery is scheduled because contacts can temporarily change the shape of the cornea. Your cornea should be in its natural shape the day of surgery. Your doctor also may tell you to stop wearing makeup, lotions or perfume for a few days before surgery. These products can interfere with the laser treatment or increase the risk of infection after surgery.
Please use the antibiotic drops as prescribed by your surgeon six hourly from the day before the surgery date. If it is determined that you are not a good candidate for the LASIK surgery:
- You will be given an explanation as to the reasons why you are not a good candidate.
- It may be recommended that you postpone your refractive surgery until further developments take place with LASIK.
- You may want to consider an alternative method of refractive surgery, or stay with your glasses or contact lenses for the time being.
LASIK is an outpatient surgical procedure; a hospital stay is not required. The surgery takes 5 to 7 minutes for each eye but the actual laser application is around 30 second for each eye. Usually both eyes are done during the same procedure. One eye at a time can also be done if the patient wants
You will be asked to sign an informed consent form after a thorough discussion of the risks, benefits, alternative options and possible complications. Don’t sign until you understand everything about the operation.
At the start of surgery, patient lies on the operation table and is positioned under the microscope of the laser. once the eye is numbed, an eyelid speculum is inserted to prevent the eyelids from blinking. Next, a thin flap is created in the outer layer of the cornea, using either a specialised mechanical blade (microkeratome) or a femtosecond laser. A little pressure or tightness may be felt at this stage. The operation does not involve any injection, stitch, bandage etc.
Next, the hinged corneal flap is lifted, exposing the treatment area. You will be prompted to look and focus at an overhead target light whilst the excimer laser is applied to the treatment area. A loud noise and a bit of smell may be noticed during the application.
Finally, the flap is repositioned upon completion which quickly adheres to the cornea. The operation does not involve any injection, stitch, bandage etc. The eyelid speculum is removed at this stage. The whole treatment lasts approximately 10 to 15 minutes for each eye.
Immediately after surgery most doctors will require you to rest in the clinic for a while and then send you home with a prescription and ask you to have a sleep for several hours. But since we insist on seeing the patient the next day after treatment, it will be necessary for outstation patients to arrange their own boarding and lodging. After being reviewed the next day the outstation patients can get back home. We recommend our patients to remain at home for the first one or two days following the surgery to avoid dust while they can perform their daily routine like reading, watching TV, Computer work etc. from next day. In most cases patients can return to work within 2/3 days following LASIK surgery.
Steroid and antibiotics eyedrops are routinely used for 1 week to help the eye heal and prevent infection.
- Your vision probably will be blurry the day of surgery, but it will improve considerably by the next day and also continue improving over the next 1 month. If there is severe pain with reduced vision, the flap may have been displaced and you should return to the eye centre immediately.
- You may experience a mild burning or sensation for a few hours after surgery. Your doctor can prescribe a painkiller, if necessary, to ease the discomfort.
- Your eyes will also feel itchy and you may have the impulse to scratch or rub your eyes. DON’T! There is a small chance that you could dislodge the corneal flap made by the doctor during surgery. This may be very harmful for your sight. So DO NOT RUB OR SCRATCH YOUR EYES! You may also notice sensitivity to light, but that goes away after a couple of days.
- Be sure to follow your doctor’s post surgery instructions.
- During the first 1-2 months your vision will fluctuate before finally stabilizing. Some dry eye may occur and your doctor can give you eye drops to counteract the dry eye. This is because your tear ducts may not be able to compensate for the new shape of your eye, so it does not produce enough moisture to keep the eye comfortable. You should contact your doctor at the first sign of irritation or blurred vision. The best advice is to follow everything your doctor says. If you can make it through the first six months with no problems, chances are your eyes will do fine from then on.
- If you experience aggravating or unusual side effects, report them to your doctor immediately