...continued from LASIK Results: What To Expect

Apples to Oranges:
Comparing Data on LASIK Lasers

The FDA has approved lasers for use in LASIK to treat myopia and hyperopia with or without astigmatism. In general, the best results have been seen in people with low to moderate myopia or hyperopia.

Depending on the laser, the percentage of LASIK recipients achieving 20/20 vision or better in FDA clinical trials has varied from around 40 percent to more than 80 percent. The percentage of those achieving 20/40 vision or better has ranged from about 75 percent to more than 95 percent.

Since the people who originally enrolled in the various FDA studies may have had different characteristics, it is impossible to compare the results of the studies head-to-head. And current results are probably better, as surgeons have gained experience and many of the lasers have been improved. The FDA results serve best to provide a general perspective of trends.

For more information on lasers that are FDA-approved for LASIK, including their approved treatment levels (that is, the amount of myopia, hyperopia, and/or astigmatism the lasers are approved to treat), read our article on LASIK lasers. Just remember that — no matter the approved treatment level of the laser — you and your surgeon can elect to do whatever you decide is appropriate and reasonable in your particular case.

Just the Numbers, Please

Here are the FDA-study results for various procedures to correct myopia and hyperopia. Most experts agree that today's numbers are probably better than these: surgeons are fairly new to the individual lasers during FDA trials, and new technology has allowed lasers to improve over the years as well.

Best Corrected Vision Targets: One Way Your 20/200 Vision Can Be Better Than LASIK-Corrected 20/40

The target values that the eyecare community has established for LASIK vision outcomes say a lot about what you can expect from the procedure. The most feared outcome of LASIK — an elective surgical procedure with safe and effective nonsurgical alternatives — is a LASIK recipient having a decrease in his or her 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 receiving LASIK, you'd at least like to be correctable to 20/20 after receiving LASIK (if LASIK falls short of providing you with 20/20 uncorrected vision).

Here's an example of a loss in BCVA: If you have 20/200 uncorrected vision prior to LASIK and see 20/20 with contact lenses or glasses, then see 20/40 (uncorrected) after LASIK but are correctable only to 20/25 with contacts or glasses, you have had a loss of one line of vision (from 20/20 to 20/25) in BCVA. Eye doctors quantify this decrease using lines in the standard Snellen eye chart. Although you have lost one line of BCVA, you have gained over 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.

Visual Acuity Targets:
How Well You Can Expect to See After LASIK

CRSQA, the surgeon-certification organization, requires its members to show that at least 90 percent of their LASIK patients achieve 20/40 uncorrected vision or better, and that at least 50 percent achieve 20/20 uncorrected vision or better. At least 85 percent of a CRSQA surgeon's LASIK patients must be within one diopter of the refractive target, and at least 50 percent must be within a half diopter. These benchmarks are considered reasonable by most refractive surgeons. Even surgeons who are not certified by CRSQA should be able to provide you with these figures based on their own experience and patient base.

You and Your Surgeon

LASIK, then, 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, the skill and experience of the surgeon is a major factor that cannot be overlooked.

In other words, the best way to anticipate what to expect from LASIK, from the standpoint both of vision outcomes and potential complications, is to take a close look at yourself and your surgeon. Together, you determine the results.

[Page updated May 2007]