Say goodbye to glasses

Published: November 29, 2005 | 2863rd good news item since 2003

If you have always wanted a permanent solution to wearing glasses, then spend just 15 minutes under the laser and you can say adios to those ugly frames. Laser surgery is popular, largely painless and every effective.

LASIK is a 15-minute operation that uses a laser to reshape the cornea. It can correct nearsightedness, farsightedness and astigmatism. For most people, the recovery period is at most a few days. [How to See Like a Hawk When You're Blind as a Bat : A Patient's Guide to LASIK Laser Vision Correction]

But LASIK, which stands for laser in situ keratomileusis, is not without its share of problems. A study published in the January 1999 Ophthalmology documented complications in 5 per cent of cases. A very small number of people do end up with worse eyesight.

Here are a few things you have to keep in mind before opting for the surgery.

• If you are over 40, LASIK probably does not mean goodbye to glasses. You’ll still need them for reading or doing close work. Some people avoid reading glasses by getting just one eye treated, which balances out their vision: one eye for seeing things up close.

• Don’t expect 20/20 vision. The vast majority of people who undergo LASIK do so to correct nearsightedness. Most of them end up with vision somewhere between 20/20 and 20/40 (a person with 20/40 vision needs to stand 20 feet away from something that a person with 20/20 vision can see fine from 40 feet away).

• Considering that people with even a mild correction tend to have 20/100 vision or worse, that is a huge gain. But if you are used to glasses or contact lenses, which correct your vision to 20/20, uncorrected vision of 20/40 after LASIK may seem like a setback.

There could be other problems after surgery, too. Some people see halos around streetlights, others suffer from contrast sensitivity. Moreover, if you are a diabetic, it is better to avoid LASIK surgery. Get your doctor to enlighten you about both the advantages and the disadvantages.

• Reshaping the eye with a laser can cause some distortion in the eye’s optics that decreases what ophthalmologists call ‘contrast sensitivity’—the narrowing of difference between dark and light.

It is roughly analogous to a photograph that is in focus but too grey. Sometimes the loss of contrast sensitivity is described as adding a ghostliness or fuzziness to vision. The reason for this optical distortion following a LASIK and other laser operations is not yet known.

• While the recovery period from LASIK is remarkably short, 30 per cent to 40 per cent of people see halos or ‘starbursts’ around bright lights for several months. This effect seems to be caused by the edge between the treated and the untreated part of the cornea bending and distorting the way light hits the eye.

People with exceptionally large pupils should not opt for LASIK surgery because the starburst effect could remain a permanent problem for them.

• People with extra-thin corneas are not good candidates because the surgeon needs enough tissue to work with. The thickness of the cornea is not necessarily related to vision. So the only way of knowing if your corneas are thick enough is to have them measured by an ophthalmologist.

Some ophthalmologists also turn away people with rheumatoid arthritis and lupus because they can have problems with dry eyes and recovery from LASIK involves some drying out of the eyes. People with diabetes also may not be ideal LASIK candidates because the outermost layer of their cornea, the epithelium, is thin and they have decreased corneal sensation.

• Finally, people who are candidates for a cataract surgery shouldn’t choose LASIK. A cataract is a cloudy lens; operating on cataracts involves taking out the clouded lens and replacing it with a new plastic or silicon version. Artificial lens implants can correct nearsightedness or farsightedness just as well as LASIK. So, there is no point in having both the procedures.

Published in LASIK and Science & Technology
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