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How Effective Is the Procedure?

Reviewed by Denis M. Humphreys, O.D.

What Are My Chances of Better Vision?

sPossibly the most important question you can ask about vision correction surgery is, "What are my chances of seeing 20/20?"

The real answer is that there's no absolute guarantee of seeing 20/20 afterward, but many people do achieve that result or better.

It's not easy to find statistics about refractive surgery results, so we've gathered some figures for you -- some from pre-FDA approval clinical trials -- that may help you decide one way or another whether you want to go ahead with the procedure.


LASIK and PRK results have been notably consistent ever since the FDA approved the first excimer lasers in 1995. Best results are achieved by low to moderate corrections, with not as good results for large corrections. Astigmatism can be treated as well, though the particular type and severity of astigmatism a person has will affect results.

Here are some numbers:

In recent studies, 98 percent of laser patients achieve 20/40 vision or better after one or more treatments.

Results have shown that 32 percent of eyes undergoing LASIK for nearsightedness achieved 20/20 or better and 83% achieved 20/40 or better the day after surgery. Six months later, 46 percent of eyes were seeing at least 20/20, with 90 percent seeing 20/40 or better.

Studies reveal that two thirds of PRK patients reach 20/20 or better vision, while 95 percent reach 20/40 or better.

A study of 1,013 LASIK-treated eyes showed 92 percent were corrected to 20/40 or better and 47 percent were corrected to 20/20 or better.

An Argentina study of highly nearsighted eyes (-10.25 to -15.00 diopters) showed average refractive error of -0.55 diopters and average best corrected visual acuity of about 20/30.

Side Effects

Halos and glare from bright lights at night, pain, starbursts, blurred vision, night vision problems, infection, dryness and itchiness are the main complications that patients have reported after vision correction surgery.

Fortunately, these problems don't occur to most patients, and when they do, they are usually temporary and treatable. Even so, you should take side effects seriously and into account when you decide whether to have refractive surgery.

Several clinical studies report that the chance of having a vision-reducing complication is less than one percent. No cases of blindness resulting from laser vision correction have been reported.

Short-term side effects from LASIK procedures included pain for one to two days, corneal swelling, double vision and light sensitivity; some patients experienced the effects for several weeks. Six months later problems included under-correction in 11.9 percent, over-correction in 4.2 percent, severe halo in 3.5 percent and severe glare in 1.7 percent. Glare and halos were worse in people with larger pupils.

For more information on laser vision correction visit our Frequently Asked Questions.