Laser Correction of refractive defects
All laser correction methods of the refractive defects (as are myopia, hyperopia and astigmatism) are based on the same principle: the reshaping of the cornea (flattening or curving it) in order to focus on the retina the images the eye forms.
There are two main categories of laser procedures for these conditions - LASIK and ASA
LASIK (Laser in Situ Keratomileusis)
LASIK is an excimer laser surgical procedure that treats the middle layers of the cornea to correct near-sightedness, far-sightedness, and/or astigmatism. LASIK is the most advanced procedure for correcting focusing problems of the eye. It is performed using numbing drops to prevent pain during the procedure. A vacuum ring secures the eye while a thin layer of the cornea is formed into a flap.
This flap is folded over, and the laser surgery is performed on the bed of the cornea that is exposed. The laser treatment reshapes the cornea to treat the refractive condition. The actual laser portion of the procedure lasts 10 to 60 seconds. The flap is then placed back into its original position and observed for 2-3 minutes to insure that it is fully adherent.
Advantages of LASIK include:
1. Little or no discomfort following the surgery;
2. Recovery of vision often within 1-2 days;
3. Little or no risk of developing haze following treatment, and
4. Ease of doing additional laser treatment should it be necessary.
As with any surgical procedure, complications can occur. Fortunately, severe complications are extremely rare.
ASA (Advanced Surface Ablation)
ASA uses the excimer laser to reshape the surface of the cornea to change its focusing power. Surface cells of the cornea (the epithelium) are gently removed from the central portion of the cornea, without the need to create a flap, to expose the region of the cornea that is treated with the laser. The actual laser time is similar to that with LASIK. The surface cells require two or more days to heal. A soft contact lens is placed over the eye during this period to serve as a bandage.
Frequently Asked Questions About Laser Vision Correction
Am I a candidate ?
To get personalized information specific to your eyes and prescription, a thorough examination by the eye doctor is necessary. The laser is capable of correcting approximately 90% of all prescriptions.
However :
- Patient less than 18 years are not a candidate for lasik.
- Power should be stabilised for one year before lasik.
- Patient with more than 8 dioptre myopia, more than 6 dioptre hyperopia and more than 5 dioptre of astigmatism are not a good candidate for the procedure.
- Adequate corneal thickness is necessary for this procedure and is checked by pachymetry.
- Laser correction is not advised if the patient has one of the following eye conditions:
- Keratoconus, active eye infection, severe dry eye, glaucoma, one eyed patients.
- Certain systemic disease such as severe arthritis, lupus, or uncontrolled diabetes can adversely affect proper healing and preclude your candidacy for lasik.
- Pregnancy is a contraindication for lasik.
Why have Laser Correction?
Laser correction can benefit a great number of people with myopia, hyperopia and astigmatism. Candidates should have a strong desire to be less dependent on corrective lenses, have established realistic expectations, and understand the risks associated with the surgery.
Does Laser Vision Correction hurt?
The LASIK procedure is associated with a sensation of pressure during certain steps of the surgery, but the patients rarely describe it as painful. There may be mild or, rarely, some moderate discomfort following LASIK, but most patients find that their eyes are quite comfortable following this procedure.
Advanced surface ablation (ASA) usually causes some discomfort. However, the discomfort only occurs during the first one to three days following the surgery. A soft contact lens is placed on the eye at the end of surgery, and this acts like a bandage to help minimize discomfort. In addition, comfort drops are prescribed to treat eye pain. The amount of discomfort is quite variable among patients. Most individuals have minimal discomfort, while some have moderate discomfort.
Are there any risks or side effects?
According to several large studies, there is approximately a 2% intra-operative and 3-5% post-operative complication rate. Most of these complications do not result in loss of 2 or more lines of best corrected visual acuity or interfere with vision long term. The rate of severe complications should be substantially less than 1%. It is important for patients to understand that laser vision correction is surgery, and a small incidence of complications is to be expected.
Are both eyes corrected at the same time?
Most patients prefer this to waiting between eyes. In the field of laser vision correction, most doctors usually do perform surgery on both eyes on the same day.
When can I return to work after Laser Vision Correction?
Most lasik patients could return to work the next day, although it is recommended to wait for a few more days. Following advanced surface ablation (ASA), most individuals find that they can return to work and drive in about 1 week. |
