LASIK Study Results
Sherman Winston Reeves, M.D.
Definition: Laser Assisted In-Situ Keratomileusis, or LASIK(link to glossary) is a refractive surgery (link to glossary) procedure which uses the excimer laser, applied to the cornea under a thin flap of corneal tissue, to help which correct refractive error(link to glossary), decreasing or eliminating the need for glasses or contact lenses.
How often do people get 20/20 vision or better after LASIK?
Data from the clinical trials for the currently used excimer lasers supports the assertion that LASIK surgery works very well for most people. For example, for the most recent trials of Custom LASIK (link to LASIK page) with the VISX S4 laser, the most commonly used excimer laser in the United States, 92% of eyes with low to moderate amounts of mypopia (link to glossary) achieved 20/20 or better at 3 months time and 98% achieved vision required for driving without glasses in most states (20/40). Higher levels myopia and hyperopic(link to glossary) patients may have a somewhat lower chance of 20/20 vision after the procedure than those with low levels of myopia (See below).
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Visual Acuity without glasses after Custom LASIK with |
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| Of 341 clinical trial eyes: | 1 Month After LASIK | 1 Year After LASIK |
| % with 20/20 vision | 92% | 98% |
| % with 20/40 vision | 98% | 100% |
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Visual Acuity without glasses after Custom LASIK with |
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| Of 184 clinical trial eyes: | 1 Month After LASIK | 1 Year After LASIK |
| % with 20/20 vision | 85% | 86% |
| % with 20/40 vision | 99% | 100% |
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Visual Acuity without glasses after Custom LASIK with |
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| Of 144 clinical trial eyes: | 1 Month After LASIK | 1 Year After LASIK |
| % with 20/20 vision | 58% | 72% |
| % with 20/40 vision | 96% | 95% |
Is 20/20 vision guaranteed with LASIK?
LASIK surgery is an extremely advanced technology for surgical vision correction. The excimer laser(link to glossasry) is one of the most precise instruments available for use in modern medicine, and it can be programmed to match exactly the refractive correction your eye needs to see well. As such, the vast majority of people undergoing LASIK surgery are very happy with their post-procedure vision. In fact, a person’s happiness with their vision after the procedure is a far more important measure of success than the somewhat arbitrary “20/20” measurement done in a dark room of a doctor’s office.
However, several factors may lead to a person having vision after the surgery which still requires additional help from glasses or contact lenses. The excimer laser is precise enough to inscribe letters on a grain of sand and could correct an inert object, such as a piece of plastic, exactly as predicted. However, in LASIK surgery, it is not being applied to something inert, but rather, a living tissue, the cornea. Because of this, and because of the individual healing response of each patient, there is some variability of response in patient to the treatment. Additionally, in individuals with higher levels of refractive error, it is harder to hit an exact refractive outcome target. A simple analogy for this is that it is much easier to make a put in golf (or correct a low amount of vision) than make a hole-in-one driving from the t-box (or precisely correct a very high amount of vision). Also, hyperopic patients, in general, may not achieve 20/20 vision as often as myopic patients. Still, as a refractive surgery technology, LASIK works extremely well in most cases and can help greatly decrease a person’s dependence on glasses and contact lenses for most viewing situations.
