LASIK is one of the safest elective surgeries available, with 99.5% of eyes achieving 20/40 vision or better (the legal threshold for driving without glasses). Serious complications that permanently affect vision occur in fewer than 1 in 2,000 cases. But “low risk” doesn’t mean “no risk,” and the nuances matter if you’re deciding whether to go through with it.
The Numbers on Vision Outcomes
The large majority of people who get LASIK end up seeing well without glasses. A major outcomes study found that 99.5% of eyes reached 20/40 or better, which is the standard for an unrestricted driver’s license in most states. The percentage hitting 20/20 is lower but still high, typically in the 90% range depending on your starting prescription.
Patient satisfaction tracks with those numbers, though it depends on how you measure it. Surveys using simple satisfaction questions find that roughly 94% of patients are happy with their results. When researchers use more detailed, validated questionnaires that probe specific visual experiences, the picture gets more complex: the dissatisfaction rate stays low at about 2.6%, but fewer people rate themselves as fully satisfied because mild side effects, even ones they’d live with again, pull their scores down.
New Visual Symptoms Are Common
Here’s where the gap between “safe” and “perfect” shows up. The FDA’s own quality-of-life study found that up to 46% of people who had zero visual symptoms before surgery reported at least one new symptom three months afterward. That’s a striking number, and it deserves context.
Halos were the most frequent new complaint, appearing in up to 40% of people who never had them before. Dry eye symptoms showed up in about 28% of previously unaffected patients. Other common additions included starbursts, glare, and ghosting around lights, particularly noticeable when driving at night.
The critical detail: fewer than 1% of participants in the FDA study said any of these symptoms caused “a lot of difficulty” with daily activities. For most people, these effects are mild, noticeable mainly in low-light conditions, and often fade over months as the eyes heal. But they’re real, and if you’re someone who drives long distances at night or works in dim lighting, they’re worth weighing carefully.
Serious Complications Are Rare
The complication that eye surgeons worry about most is called ectasia, where the cornea gradually weakens and bulges forward after surgery. This causes worsening nearsightedness and blurred vision that can’t be fully corrected with glasses. It can appear days to years after an otherwise uncomplicated procedure. The estimated incidence is less than 1 in 2,000 cases, and proper screening (adequate corneal thickness, no signs of existing corneal disease) reduces that risk further.
Flap-related complications are another category. During LASIK, a thin flap is created on the cornea’s surface, reshaped underneath, then laid back down. Occasionally, skin cells from the surface can grow underneath the flap in the weeks after surgery, a problem called epithelial ingrowth. This happens in about 1% of first-time procedures and 2% of enhancement surgeries. Most cases are minor and just monitored, but visually significant ingrowth requires the flap to be lifted and the cells scraped away. Recurrence after that initial treatment can be as high as 44%, sometimes requiring additional interventions like suturing the flap edges down more tightly.
Bladeless vs. Blade Technology
Modern LASIK centers increasingly use a femtosecond laser rather than a mechanical blade to create the corneal flap. The laser produces a flap of more uniform thickness, which leaves more corneal tissue intact underneath and reduces the chance of flap irregularities. Flap-related complications, including epithelial ingrowth, are lower with the laser approach. The tradeoff is a small chance of temporary light sensitivity in the first few weeks, which resolves on its own. If you’re comparing clinics, asking whether they use femtosecond laser flap creation is a reasonable question.
Vision Can Shift Over Time
LASIK reshapes your cornea to correct your current prescription, but it doesn’t freeze your eyes in place forever. Some degree of regression, where your vision drifts back toward nearsightedness, is possible over the following years. A 10-year follow-up study found that regression was more likely in people who had higher prescriptions corrected and that the rate of change slowed over time rather than continuing indefinitely. Enhancement procedures (a second, smaller correction) can address this and don’t appear to increase the risk of further regression. Many clinics include one enhancement in their pricing for this reason.
Separately, LASIK does nothing to prevent age-related changes. Nearly everyone develops presbyopia (difficulty focusing on close objects) starting in their mid-40s, and cataracts eventually affect most people. If you get LASIK at 25, expect that you’ll still need reading glasses later in life.
What Makes You Higher Risk
Not everyone faces the same odds. Your risk profile depends heavily on your anatomy and health. Corneal thickness is one of the biggest factors: surgeons generally want at least 270 microns of corneal tissue remaining after the procedure, with 310 microns or more being ideal. Thinner corneas increase the chance of ectasia. If your corneas are on the thin side, a surface-based procedure called PRK achieves similar vision results with a longer healing period but no flap-related risks.
Other factors that raise your risk or may disqualify you outright include unstable prescriptions (your vision is still changing year to year), very high prescriptions that require removing more tissue, corneal conditions like keratoconus, chronic dry eye that’s already significant before surgery, autoimmune diseases that impair healing, and large pupils that extend beyond the treatment zone in dim light (contributing to halos and glare).
A thorough pre-surgical evaluation catches most of these issues. The quality of that screening matters as much as the surgery itself. Clinics that turn away a meaningful percentage of candidates are generally being more careful than those that approve almost everyone.
Putting the Risk in Perspective
Wearing contact lenses carries its own risks that people rarely think about. Long-term contact lens use increases the chance of corneal infections, some of which can cause permanent scarring and vision loss. One study estimated the 30-year cumulative risk of a serious contact lens infection at roughly 1 in 100 for daily wearers, which is actually higher than the risk of a serious LASIK complication. That doesn’t make LASIK risk-free, but it reframes the comparison. The real question isn’t whether LASIK has risks. It’s whether those risks are acceptable to you, given how much you value being free of corrective lenses and how well you tolerate uncertainty about mild side effects like halos and dryness that may or may not resolve completely.