What is refractive error?
The normal eye is able to focus light from a distance onto the retina. In myopia, or nearsightedness, the light focuses in front of the retina, causing a blurry image at a distance. Closer images, however, will be clearer.
In the farsighted eye, the image is focused beyond the retina. In our youth, we have an ability to compensate for this by using a muscle within the eye to adjust the focus--this is called accommodation. This allows images to be in focus both far and near. As we age, we begin to lose our ability to accommodate, so farsightedness is commonly a problem later in life.
In astigmatism, the eye has more than one curvature--like an egg--causing the image to have more than one focusing point at the retina.
What is LASIK?
LASIK is a procedure in which the curvature of the eye is altered to reduce nearsightedness (myopia), farsightedness (hyperopia), and astigmatism. LASIK stands for LAser In-situ Keratomileusis. In this procedure, a thin peel is created from the surface of the cornea with an instrument. After the peel is made, it is turned back to expose the inner layer of the cornea, which is then reshaped with the laser. Finally the top layer is put back into place.
This examination is by appointment. Depending on your needs, this comprehensive evaluation takes about an hour and includes a wide dilation of your pupils. Your vision up close will be blurry for about four hours and your pupils are usually dilated until the next day. In order to apply the most accurate laser correction, you must be out of your contacts before the eye examination, as well as the procedure, for one to four weeks, depending on the type of lenses. The examinations of pre-LASIK evaluation includes visual acuity, intra-ocular pressure (eye pressure), topography of cornea, keratometry, slit-lamp biomicroscopy and funduscopy etc.
Who is appropriate for LASIK surgery?
Generally speaking, many people request LASIK surgery because they encounter bothersome situation in their jobs, such as military personnel, athletics etc. There are some people who had the problem of intolerance of contact lens wearing and inconvenience of spectacle wearing or just for cosmetics going to have the surgery. Candidates should have a strong desire to become less dependent upon corrective lenses and be willing to accept the risks of having surgery.
The following criteria are recommended:
- Be at least 18 years of age
- Stable vision for one year (slight change in prescription may not qualify you)
- Eyes are free of disease
- Not pregnant or breast-feeding
Post-operative instructions and recovery
- Please do not rub or touch your eyes or around your eyes for one week.
- It is normal for your eyes to be scratchy and blurry.
- Please sleep when you go home for three to four hours.
- Wear the plastic shields when sleeping for the next week.
- When you wake up use your eyedrops by doctor's order.
- Use artificial tear drop at least every two hours and every hour may be helpful. The more tear drops that you use, the more comfortable that you will be.
- Wear sun glasses when outside for the next three months.
- You may take Panadol, Scanol, Aspirin for discomfort if needed. The best way to relieve discomfort is to sleep and then to increase the frequency of the tear drops.
Your vision will also be initially cloudy, just as looking through a thick fog. By the time you awaken after 3-4 hour nap, it should be markedly improved. Your vision will get better throughout the day and will be much better by morning. Some fluctuation of vision is expected over the first several weeks. The frequent use of artificial tear drops will help the vision stabilize more quickly.
If you are 40 or over you may need reading glasses. Occasionally cannot correct all of your prescription if there is not enough corneal tissue. You may need for corrective lenses after the surgery. If you have any regression and you decide against enhancement, you will definitely need glasses to improve your vision.
Advantages of LASIK
The advantage of LASIK over other procedures is that it leaves the epithelium virtually unharmed. Recovery time is rapid and there is very little pain. It has a very high level of outcome predictability and uses state of the art technology. Another advantage with LASIK is that should enhancements be necessary, it is a simple procedure to re-open the flap and zap the eye again. Lasik has become the prescribed procedure for vision correction surgery.