In my opinion, laser eye surgery works best, and is safest for those with a mild to moderate degree of myopia (nearsightedness) and/or a mild to moderate degree of astigmatism (irregularly shaped cornea). If you have a very high prescription, more tissue needs to be removed from the cornea - this can increase the risk of post-operative complications. If you are hyperopic (farsighted), it is more difficult to correct and the results are less predictable. I generally do not recommend laser eye surgery for those who are farsighted because of the poorer outcomes compared to those who are nearsighted. Ask your optometrist if your prescription is ideal for laser eye surgery and what your odds are of successfully achieving good vision without glasses and contact lenses. You should feel confident of being glasses free after having the surgery (if you're over the age of 40, there's a caveat - more on that below).
Other very important criteria include:
Your eyes must be healthy - no glaucoma, cataracts, severe dry eye, or infections.
The cornea of your eye must have adequate thickness to perform the surgery safely (this is measured by an ultrasound device at the laser eye surgery clinic).
Your pupils under dim lighting conditions shouldn't be too large (this will also be measured at the laser eye surgery clinic). Very large pupils can increase the risk of permanent glare and halos around lights at night.
If you're pregnant or nursing, the hormonal changes can cause changes to your vision and the shape of the cornea. Wait until after your hormones are back to normal levels.
You cannot have a degenerative or autoimmune disease (a few examples are arthritis, lupus, Crohn’s disease, type I diabetes).
An Important Consideration for Those Over 40
If you're over the age of 40, in addition to what I discussed above, you have to factor in how your near vision (reading, using your computer and looking at anything within arms-length) will be affected. We will all experience presbyopia over the age of 40. Presbyopia is a normal part of aging that causes our eyes to lose the ability to see things clearly up close. Having laser eye surgery may cause your near vision to worsen. It is very important that you discuss the impact on your near vision with your optometrist - this will vary according to your vision and how you typically use your eyes during the day. There are techniques that can reduce your dependency on reading glasses following surgery, make sure to ask about these before deciding on surgery.
Some Final Thoughts
Having laser eye surgery can be potentially life changing (it was for me). My goal was to give you some general guidelines and advice based on my years of experience providing care to patients seeking and/or undergoing laser eye surgery. If you’re highly motivated to have surgery, first see your optometrist for a thorough, comprehensive eye exam and indicate your interest in having laser eye surgery. Your optometrist will be able to give you a good idea if you are an ideal candidate. Your optometrist may also be able to refer you to a reputable clinic and surgeon for a consultation. Also, do choose a reputable clinic and surgeon. The pre-operative consultation and testing is very important to ensure you will have a safe, successful outcome. Pay attention to how you're treated. Laser eye surgery is a medical procedure; you should be treated in a professional and compassionate manner as if you're a patient and not given a sales pitch as if you were a consumer shopping for a product. Assuming you’re a good candidate, once you’ve made your decision, you won’t regret it!