LASIK, or Laser-Assisted in Situ Keratomileusis, is a laser refractive surgery that corrects common vision problems like myopia (nearsightedness), hyperopia (farsightedness), and astigmatism. By reshaping the cornea, the clear front surface of the eye, LASIK improves how light is focused onto the retina. The primary goal is to decrease or end a person’s reliance on glasses or contact lenses.
Expected Visual Acuity
A primary motivation for undergoing LASIK is achieving clearer vision, and outcomes are broadly positive with patient satisfaction rates as high as 95.4%. Statistically, a large majority of individuals see a dramatic improvement in their uncorrected vision. Around 90% of LASIK patients achieve 20/20 vision, and approximately 99.5% reach a visual acuity of 20/40 or better. This 20/40 benchmark is noteworthy as it represents the legal requirement for driving without glasses in most jurisdictions.
In some cases, results can surpass the 20/20 mark, as 40% to 50% of patients find their vision is better than 20/20 after the surgery. Many people find they can eliminate corrective eyewear for most daily activities.
Common Visual Disturbances and Side Effects
Following LASIK surgery, it is common for patients to experience certain visual disturbances as their eyes heal. These effects are temporary and resolve over a period of weeks to months. One of the most frequently reported side effects is dry eye, which occurs because the procedure can temporarily reduce tear production. This can cause a gritty sensation but is usually managed effectively with lubricating eye drops.
Beyond dryness, patients often notice changes in their quality of vision, particularly in low-light conditions. Symptoms like glare, halos around bright lights, and starbursts are common, especially when driving at night. These visual artifacts are a normal part of the healing process as the cornea adapts and swelling subsides.
Light sensitivity is another potential side effect that can occur in the initial days and weeks after the procedure. While most of these symptoms are mild and diminish within the first few months, a small number of people may experience them for up to a year. Serious complications that result in vision loss are very rare, occurring in less than 1% of cases.
Long-Term Vision Changes
For most individuals, the vision correction achieved with LASIK is stable and permanent. However, the surgery does not prevent the natural aging process of the eye. One of the most significant age-related changes is presbyopia, a condition that affects nearly everyone, starting in their 40s. Presbyopia is the gradual loss of the eye’s ability to focus on close objects, which leads to the need for reading glasses.
LASIK corrects refractive errors by altering the cornea, but presbyopia is caused by the stiffening of the eye’s natural lens, a part of the eye that LASIK does not treat. Therefore, even after successful surgery for distance vision, a person will likely still require reading glasses as they enter middle age. This is a normal part of aging and is not a complication of the surgery.
In a minority of cases, some individuals may experience a slight shift in their vision years after the procedure, a phenomenon known as regression. This involves a partial return of the original refractive error, such as nearsightedness or astigmatism. Regression is often mild and may not require any intervention, but for some, an additional procedure, called an enhancement, may be an option.
Factors Influencing Individual Results
The final outcome of LASIK surgery is not uniform for every patient and can be influenced by several distinct factors. A person’s pre-operative prescription plays a significant role; individuals with very high degrees of nearsightedness, farsightedness, or astigmatism may have less predictable results.
Corneal thickness is a major consideration, as the procedure involves removing a small amount of corneal tissue. A cornea that is too thin may not be suitable for LASIK. Similarly, pupil size is measured before surgery, as larger pupils can be associated with a higher likelihood of experiencing night vision issues like halos and glare.
The technology used during the procedure and the surgeon’s experience also contribute to the final results. Modern advancements, such as wavefront-guided lasers, allow for a more customized and precise treatment. The skill of the surgeon in performing the procedure and managing aftercare is another component that shapes the overall success and visual quality achieved.