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What is LASIK?

Quite often patients who are in for a routine eye exam will ask one of our optometrists about refractive surgery. Many of these people have worn contacts or thick glasses for years; some are great candidates for Lasik, and others not so much. Read on to learn more.

lasik illustration

Am I a good candidate for Lasik?

Patients often have a good deal of anxiety when thinking about getting eye surgery. While every surgery has risks, Lasik has been refined to a point that the outcomes are reliably good and the risk of serious complications is quite low. Still, it’s important to become well educated about the treatment’s risks and benefits, and the pros and cons of different surgeons and surgeries. While the eye doctors at Cannon EyeCare do not perform Lasik procedures, we do coordinate surgical care with a few carefully selected surgeons. We would see the patient for a pre-operative eye exam and evaluation, and then see the patients for 3-4 additional post-operative medical eye exams to monitor their recovery from surgery. Letters back and forth between your optometrist and the ophthalmologist/surgeon keep everybody in the loop.

One way to test whether you’re a candidate is to look at surgical data showing who gets great results that last. The ideal lasik candidate:

  • is nearsighted at a level of about -2.75 to -7.00
  • has mild to moderate (less than 3 Diopters of) astigmatism
  • has a stable glasses Rx
  • is age 25-35
  • and has healthy eyes

The reason that myopia makes you a good candidate is that myopes (nearsighted patients) tend to get the most precise, predictable, and stable correction from Lasik. If a hyperopic (farsighted) patient chooses to get Lasik, they are more likely to need glasses within a few years. Mild to moderately nearsighted patients (-0.25 to about -2.50 diopters) are not such great candidates for Lasik because their vision is not so bad in the first place. While it can be frustrating to need glasses to drive, nearsighted people with a moderate Rx can read and /or use computers with ease, which is kind of nice in todays society. Patients who are a -4.00 and up are severely myopic; these people cannot even read their alarm clock without finding their glasses first. Clearly, they get a larger benefit from refractive surgery than those with a mild Rx. Patients beyond may not be a candidate for Lasik, but read our blog about PRK for other options.

Lasik also helps people with astigmatism, but it is not ideal for those with 2 or more diopters of astigmatism. Farsighted (aka Hyperopic) people because they get less improvement than their peers and are also less likely to have lasting reults. Not all nearsighted patients should get Lasik either, so ask your doctor if it’s right for you.

Explaining the stable glasses Rx is easy: your surgeon does not want to try to hit a moving target. Both your ophthalmologist (surgeon) and your optometrist (primary care eye doctor) want you to be happy with your result 2 years or even 10 years down the line. Waiting until your Rx is stable (typically age 25-28) benefits everybody involved, most of all the patient.

The reason the age is a factor is two fold:

  1. you need to be at least 24 or 25 for a stable Rx & a safe outcome, and
  2. everyone expects they will be glasses-free after the surgery, but people in their late 30s and older will need reading glasses for near work within a few years of getting refractive surgery. As long as the patient understands this limitation, Lasik can be performed on patients in their 40s, 50s, as long as they meet the other criteria.
  3. Typically by the time a patient is in their 60s they would be counseled against getting refractive surgery due to the fact that they would need cataract surgery within a few years.

It is quite likely clear that your surgeon will not want to operate if your eyes are not healthy to begin with. Some things like mild to moderate blepharitis can be brought under control by your optometrist with a few medical eye exams before you see the surgeon. Other things like moderate to severe dry eye or a corneal dystrophy may make you a non-candidate. See your local optometrist to see if you might be a good candidate for refractive surgery if you want to live glasses and contact-lens free.


Sincerely, Dr. Mark J. Cannon, optometrist @ Cannon EyeCare (at Market Optical) in Seattle, Washington