LASIK Eye Surgery Results: Are you likely to see 20/20 after LASIK?

LASIK Results: What to Expect

By Keith Croes, with updates by Diane Donofrio Angelucci;
contributions and review by Vance Thompson, MD

LASIK eye surgery results have continued to improve, along with supporting technology and surgeon skill, which should offer some reassurance to candidates who are unsure about what to expect.

Thanks to LASIK, millions of people throughout the world are less dependent on glasses or contact lenses. Still, the decision to have LASIK should be approached with caution. Because surgery is involved, some serious potential risks — though rare — are associated.

Because LASIK is an elective procedure, you will be contemplating surgery on an otherwise healthy eye. For that reason, always consider that you have the option of safe and effective nonsurgical alternatives, such as glasses and contact lenses.

When considering LASIK, do some homework and consult with your eye doctor to learn more about the procedure. Ask about potential LASIK complications as well as visual outcomes.


Inquire about the technology your LASIK surgeon uses for the procedure. In LASIK, an ultra-thin, hinged flap is lifted from the surface of your eye. After laser energy is applied to reshape the cornea, the flap is replaced to serve as a type of natural bandage.

Does your surgeon prefer a blade-created flap or a laser-created flap associated with the recent innovation of bladeless LASIK? 

Consider also that newly developed eye-tracking technology in an excimer laser helps make inadvertent eye movement less of a problem during a procedure.
Also, custom or wavefront-guided LASIK reduces the chance of nighttime visual problems such as glare and halos.

After you go through the education process to understand your best treatment options and the available technology, it is important to understand your surgeon's level of experience. After a balanced discussion about all these issues, you will be more prepared to make an educated decision, which will improve your chance of a good LASIK outcome.

Possible LASIK Complications

LASIK carries a slight risk of short- and long-term complications. Most people respond well to treatment, but some cases are more difficult. Very rarely, permanent problems can result.

According to guidelines from the Eye Surgery Education Council (ESEC) founded by members of the American Society of Cataract and Refractive Surgery, fewer than 1 percent of LASIK patients experience serious, vision-threatening problems.
LASIK complications can include:

• More serious problems such as eye infection, chronic dry eye and LASIK flap problems.
• Less serious complications that generally clear up on their own as the eye heals, including halos, haze and glare.

The ESEC says most LASIK complications can be treated and usually clear up within several months.

Studies consistently show that LASIK complications decline as surgeon experience increases. So you can increase your chance of a good outcome by choosing an experienced surgeon.

It's also important to remember that your general health and eye health both influence the risk of certain complications. For example, you may be at greater risk of LASIK complications if you have a disease such as diabetes that can interfere with your body's normal healing responses. Of course, you will need to discuss your general health with your eye doctor.

Also consider that, even under the most ideal circumstances with a technically flawless surgical procedure, each patient responds and heals differently after eye surgery.

LASIK Studies and Safety Standards

The eye care community sets high standards for LASIK success. For a LASIK laser to receive FDA approval, manufacturers are expected to have adverse event rates of less than 1 percent during clinical trials.

The FDA definition of adverse event includes a list of specific problems such as corneal swelling, flap problems, uncontrolled intraocular pressure and a detached retina.
At this time, no central database of LASIK outcomes exists. Most of what is known about visual acuity outcomes after LASIK is based on various clinical studies, especially trials the FDA requires laser manufacturers to perform to obtain approval.
Most clinical studies of LASIK vision outcomes have a few elements in common. These include:

• An assessment of how many people achieve 20/20 vision or better (so-called "perfect" vision) and how many achieve 20/40 vision or better (the minimum visual acuity required to obtain a driver's license in most states).
• A discussion of how many people get to within one diopter or a half diopter of zero refractive error. (Myopia, hyperopia and astigmatism are all refractive errors. Zero refractive error is called emmetropia.)
• Details about possible adverse events associated with LASIK.

To monitor vision changes during the LASIK recovery period, many studies measure visual outcomes immediately after surgery, several days later and at one, three and six months after the procedure.

Apples to Oranges: Comparing FDA Data on LASIK Lasers

The FDA has approved lasers for use in LASIK to treat myopia and hyperopia, with or without astigmatism. Best results generally have occurred in people with low to moderate myopia.
When considering FDA studies, however, it is impossible to compare study results head-to-head. This is because people who enrolled in one study originally may have had different characteristics than those who had LASIK in a study for another company's laser.
Results from the same laser also can vary, depending on how people were selected for the study. Some studies may eliminate those with higher amounts of refractive error, for example, while others may need to assess results specifically for these types of vision problems.
Furthermore, later results with these lasers are probably better, as surgeons gain experience and many of the lasers are improved. In short, FDA results serve best to provide a general perspective of trends.
Our article on LASIK lasers provides more information about FDA-approved lasers for LASIK, including their approved treatment levels. For example, you can learn about the amount of myopia, hyperopia and/or astigmatism the lasers are approved to treat.
Just remember that, no matter the approved treatment level of the laser, you and your surgeon can choose to do whatever you think is appropriate and reasonable in your particular case.

Best-Corrected Vision After LASIK

The target values that the eye care community have established for LASIK vision outcomes say a lot about what you can expect from the procedure.
The most feared outcome of LASIK is a decrease in best possible vision, something doctors call best corrected visual acuity (BCVA), or sometimes best spectacle-corrected visual acuity (BSCVA).
In other words, if you can be corrected to 20/20 with glasses or contact lenses before undergoing LASIK, you'd like to be correctable to at least 20/20 after LASIK (if LASIK falls short of giving you 20/20 uncorrected vision).
For example, if you have 20/200 uncorrected vision before LASIK and see 20/20 with contact lenses or glasses, then see 20/40 uncorrected after LASIK but are correctable to only 20/25 with contacts or glasses, you have lost one line of BCVA (from 20/20 to 20/25) on a standard eye chart.
But even though you lost one line of best corrected visual acuity, you gained more than six lines of uncorrected vision (from 20/200 to 20/40).
The FDA expects laser manufacturers to show that no more than 5 percent of patients in clinical trials lose more than two lines of BCVA and that less than 1 percent of patients have BCVA worse than 20/40.

How Well Can You Expect To See After LASIK?

In a major report discussed on the American Academy of Ophthalmology website, 64 LASIK studies published since 2000 were reviewed with these results reported:

• In a detailed analysis of all 64 studies, a median of 92 percent of eyes with myopia or myopic astigmatism achieved a correction within 2.0 diopters of target. Results were better for eyes with low or moderate myopia, compared with high myopia.
• In 22 studies of outcomes involving people with low to high levels of myopia, a median of 94 percent of eyes achieved 20/40 or better vision after surgery and did not require correction with glasses or contact lenses (uncorrected visual acuity or UCVA). A median of 99 percent of people with low to moderate levels of myopia had 20/40 or better UCVA, and a median of 89 percent of people with high myopia had the same result.
• In these same studies, outcomes for people with hyperopia also were examined. Results showed that a median of 88 percent of eyes with hyperopia and hyperopic astigmatism achieved correction within 1.0 diopter of target, resulting in at least 20/40 UCVA.

According to a major analysis of scientific literature by the American Society of Cataract and Refractive Surgery reported in 2008, worldwide satisfaction rates among LASIK patients is 95.4 percent.
Some studies, such as one reported in the October 2008 issue of Journal of Cataract and Refractive Surgery, continue to show a slight trend toward better LASIK outcomes if you don't require a high degree of correction — for example, if you are moderately nearsighted as opposed to extremely nearsighted.
More details about LASIK outcomes will be known after the FDA completes an ongoing Quality of Life study that involves detailed examination of the types of vision improvement people have, along with possible side effects that might not ordinarily be reported in clinical trials. In late March 2011, the FDA began selecting sites throughout the United States where people who have undergone LASIK will be surveyed to assess their satisfaction with their LASIK outcome and to document adverse visual symptoms or complications.
Most LASIK surgeons should be able to provide you with benchmarks, such as figures showing what percentage of their patients have achieved UCVA of 20/20 or better after LASIK.

LASIK Results and Your Eye Surgeon

LASIK is like many other surgical procedures. Where you start is an important predictor of where you end up. Results are affected by the health of your body in general, your eyes in particular and the status of your current vision.
And, as with all other surgical procedures, surgeon skill and experience are major factors that cannot be overlooked.