LASIK is a laser eye surgery that corrects common vision problems so you can see clearly without glasses or contact lenses. It treats three specific refractive errors: nearsightedness (myopia), farsightedness (hyperopia), and astigmatism. Each of these conditions involves light focusing incorrectly as it enters the eye, and LASIK fixes the problem by permanently reshaping the cornea, the clear front surface of your eye.
The Vision Problems LASIK Corrects
Your eye works like a camera. Light passes through the cornea and lens, which bend it to focus on the retina at the back of the eye. When the shape of your eye is slightly off, light lands in the wrong spot, and your vision blurs. That’s a refractive error.
In nearsightedness, your eyeball is slightly too long or your cornea curves too steeply, so distant objects look blurry while close-up things stay sharp. Farsightedness is the opposite: the eyeball is too short or the cornea too flat, making nearby objects harder to focus on. Astigmatism happens when the cornea is shaped more like a football than a basketball, distorting vision at all distances. LASIK can treat any of these individually or in combination, though people with extreme prescriptions in any category may not qualify.
How the Procedure Works
LASIK happens in two phases, both performed while you’re awake with numbing eye drops. The entire process takes roughly 15 to 30 minutes for both eyes.
First, the surgeon creates a thin, hinged flap on the surface of your cornea. This is done either with a tiny oscillating blade (a microkeratome) or, more commonly today, with a femtosecond laser. The laser version works by firing ultrashort pulses of energy that create thousands of microscopic bubbles at a precise depth in the cornea, essentially separating a thin layer of tissue to form the flap. This step takes about 30 to 45 seconds per eye.
Once the flap is lifted back, a second laser called an excimer laser reshapes the exposed corneal tissue underneath. This laser operates in the ultraviolet spectrum and works through a process that breaks molecular bonds in the tissue without generating heat. That precision matters: each pulse removes tissue to a depth of about one micron (one-thousandth of a millimeter), and surrounding tissue stays completely undamaged. For a nearsighted eye, the laser flattens the center of the cornea. For a farsighted eye, it steepens the center. For astigmatism, it smooths out the irregular curvature. After reshaping is complete, the surgeon lays the flap back into position, where it adheres naturally without stitches.
Conventional vs. Custom LASIK
Standard LASIK corrects the same basic prescription you’d get in glasses or contacts: nearsightedness, farsightedness, and astigmatism. These are called lower-order aberrations. But your eye also has subtler optical imperfections, called higher-order aberrations, that a standard prescription doesn’t address. These can cause glare, halos around lights, and reduced contrast, especially at night.
Custom LASIK (also called wavefront-guided LASIK) uses a special device that sends a beam of light into your eye and measures how it reflects back. This creates a detailed three-dimensional map of your eye’s unique optical system, capturing both the basic prescription errors and the finer imperfections. The excimer laser then uses that map to deliver a treatment tailored to your individual eye rather than just your prescription. The result is the potential for sharper, higher-quality vision, particularly in low-light conditions.
Success Rates and What to Expect
LASIK has one of the highest satisfaction rates of any elective procedure. Current data shows that 99 percent of patients achieve better than 20/40 vision (the legal threshold for driving without corrective lenses in most states), and more than 90 percent reach 20/20 or better.
Recovery is fast but gradual. In the first 24 hours, your vision will likely be blurry or hazy, and you may experience mild irritation, tearing, or sensitivity to light. Most people notice a dramatic improvement within the first day or two. Over the following weeks, vision continues to stabilize. You’ll use artificial tears to keep your eyes comfortable, and activity restrictions are gradually lifted during the first month. Full visual stabilization can take several weeks to a few months.
Common Side Effects
Dry eye is the most frequently reported side effect. About 35 percent of patients experience some degree of dryness after the procedure, though this is partly because roughly a third already had mild dry eye before surgery. The reassuring part: for the vast majority, symptoms resolve within two to four weeks. The cornea’s nerve supply, which helps regulate tear production, is temporarily disrupted during flap creation, and tear function generally returns to normal over a six-month period.
Other temporary side effects include halos or glare around lights at night, sensitivity to bright light, and minor fluctuations in vision clarity during healing. These tend to fade as the cornea stabilizes.
Who Qualifies for LASIK
LASIK is FDA-approved for adults 18 and older, though most surgeons prefer patients to be in their mid-20s when the eyes have fully matured. Your prescription needs to have been stable for at least two consecutive years. During a consultation, your surgeon will measure your corneal thickness to confirm there’s enough tissue for the reshaping process. Corneas that are too thin can lead to serious complications.
Several conditions can disqualify you. Autoimmune diseases like lupus or rheumatoid arthritis, immunodeficiency conditions, and diabetes can all impair healing. Pregnancy and breastfeeding cause hormonal shifts that temporarily change your prescription, so surgery is postponed until after. A history of certain eye conditions also rules out the procedure, including keratoconus (a progressive thinning of the cornea), glaucoma, recurring herpes infections affecting the eye, and significant prior eye injuries or surgeries.
People who participate in contact sports like boxing, wrestling, or martial arts face added risk because a blow to the eye could dislodge the corneal flap even years after surgery. Preexisting dry eye is another concern, since LASIK tends to worsen it, at least temporarily. Unusually large pupils can also increase the chance of nighttime glare and halos. All of these factors are evaluated during a pre-surgical screening to determine whether LASIK is a safe option for your specific eyes.