What Are The Chances That Eye Surgery Will Give You Improved Vision?

As a patient, what are the important statistics for you to know, and how can you interpret outcomes? First of all, you likely want to know your chances of achieving at least 20/40 vision. This is a key number since 20/40 vision is required to drive legally without eyeglasses or contacts. Second, you probably also want to know your chances of achieving optimal 20/20 vision. Third, you may wish to know the likelihood of needing an enhancement procedure after the initial surgery. All of the above numbers will vary according to the surgeon you choose and your prescription. Below are eye conditions and your chances of success based on statistics of operations.

Mild Myopia: A patient with mild myopia, or nearsightedness, has a nearly 100 percent chance of achieving 20/40 vision or better and being able to drive without eyeglasses or contacts. The chance of achieving 20/20 vision without correction is 98 percent, but this statistic includes patients who require an enhancement procedure, as well as those who do not. The chance that a patient with mild myopia will need an enhancement procedure is 1 percent. Mild myopia is defined as less than -3.00 diopters, with or without astigmatism.

Moderate Myopia: After the initial procedure, nearly 100 percent of patients with moderate myopia achieve 20/40 vision or better. Of these, 88 percent achieve 20/20 vision or better. There is a 3 percent chance of needing an enhancement procedure if you fall into this category. After undergoing an enhancement, almost 100 percent of patients see 20/40 or better and 96 percent see 20/20 or better. Moderate myopia is defined as a refractive error between -3.00 and -6.00 diopters.

Severe Myopia: These patients have a 99 percent chance of seeing 20/40 or better after the initial procedure. Patients with severe myopia have a 6 to 8 percent chance of needing an enhancement procedure, after which they have a 99 percent chance of seeing 20/40 or better and a 90 percent chance of seeing 20/20 or better. Severe myopia is defined as a refractive error between -6.00 and -9.00 diopters.

Extreme Myopia: Patients with extreme myopia have an 89 percent chance of achieving 20/40 vision or better after the initial procedure. Because of the high level of correction, approximately 12 to 16 percent of this group will need enhancements. After enhancement, 77 percent of patients will have 20/20 vision or better.

Many patients with extreme myopia do well. However, other variables such as the thickness and the steepness of the cornea come into play. Patients in this group need to thoroughly discuss the risks and benefits of LASIK, as well as other options, with their doctor. Although enhancement rates are higher in this group of patients, there may be limitations on what can be done due to other variables in the eye. Extreme myopia is considered a refractive error higher than -9.00 diopters.

Astigmatism: Patients with mild astigmatism can expect nearly identical outcomes and enhancement percentages to those patients with myopia only. The presence of moderate or high degrees of preoperative astigmatism will reduce your chance of achieving 20/20 vision after the initial procedure, making it more likely that you will want to have an enhancement. Mild astigmatism is defined as a refractive error of 1.00 diopter or less.

Hyperopia: The statistics on LASIK outcomes for patients with hyperopia come from a multi-center trial that was conducted for FDA approval of an excimer laser called the VISX Star S2. The participating LASIK surgeons treated patients with hyperopia in the range of +1.00 to +6.00 .diopters. In this study, after the initial LASIK procedure 91 percent of the patients achieved 20/40 vision or better, and 53 percent saw 20/20 without eyeglasses. Patients treated for hyperopia should be aware that their healing time is slightly longer than for patients with myopia, and the chance that they will need an enhancement is slightly higher. These numbers are variable, depending on the patient's original prescription and the skill and experience level of the surgeon.