LASIK, or Laser-Assisted In Situ Keratomileusis, is a refractive surgical procedure designed to reshape the cornea, the clear front surface of the eye. This reshaping allows light to focus more precisely on the retina. The primary goal of LASIK is to enhance visual acuity and reduce or eliminate the need for corrective lenses.
Correctable Vision Conditions
LASIK primarily addresses refractive errors, which occur when the eye does not bend light properly. Nearsightedness, or myopia, is a condition where the cornea is too curved or the eyeball is too long, causing distant objects to appear blurry because light focuses in front of the retina. Farsightedness, or hyperopia, arises when the cornea is too flat or the eyeball is too short, leading to difficulty seeing nearby objects clearly as light focuses behind the retina. Astigmatism involves an irregularly shaped cornea, which causes light to scatter unevenly, resulting in distorted or blurry vision at all distances.
Measuring Successful Outcomes
The effectiveness of LASIK is assessed by measuring visual acuity and the reduction in reliance on corrective eyewear. Achieving 20/20 vision or better is a common benchmark, indicating sharp, clear vision. Another metric is 20/40 vision or better, which is the legal standard for driving without correction in many places.
Studies indicate that over 90% of LASIK patients achieve 20/20 vision or better, with some reports even higher than 95%. Around 99% achieve 20/40 vision or better following the procedure. This high rate of visual improvement leads to a significant decrease in dependency on glasses or contact lenses. Patient satisfaction rates for LASIK are also high, exceeding 95% in many studies.
Factors Influencing Individual Results
Several factors contribute to individual outcomes following LASIK. Patient suitability is important, requiring a stable prescription for at least one year and adequate corneal thickness. Overall eye health is also important, as certain conditions like severe dry eye or specific corneal diseases can preclude someone from being a candidate. The type and severity of the pre-existing refractive error also play a role, with lower degrees of nearsightedness generally having more predictable outcomes.
The technology used influences results, including advanced laser platforms such as femtosecond lasers for flap creation and excimer lasers for corneal reshaping. Modern wavefront-guided or topography-guided LASIK systems customize the treatment to the unique contours of each eye, potentially improving precision. The surgeon’s experience and adherence to rigorous screening protocols are also influential, as they ensure proper patient selection and meticulous execution of the procedure.
Long-Term Visual Stability
The visual correction achieved through LASIK is long-lasting because the procedure permanently reshapes the cornea. For patients, the enhanced vision remains stable for years, even decades. However, LASIK does not prevent the natural aging processes of the eye. Age-related vision changes, such as presbyopia (the gradual loss of near vision typically starting around age 40), can occur independently of the LASIK procedure. While LASIK corrects distant vision, it does not alter the eye’s natural lens, which is responsible for presbyopia.
A slight regression of the refractive error can occur over time, which may necessitate an enhancement procedure, although this is uncommon. Studies indicate that over 86% of patients retain 20/40 vision or better after 10 years, with about 52% maintaining 20/20 vision at the same mark.
Common Post-Procedure Visual Experiences
Following LASIK, patients may experience temporary visual effects as their eyes heal and adapt to the reshaped cornea. Dry eyes are common, often improving over time, though some individuals may have persistent symptoms. This can arise from the procedure disrupting tear production or corneal surface nerves.
Other visual effects include glare, halos, and starbursts, especially noticeable at night or in low-light conditions. Halos appear as bright circles around light sources, while starbursts present as rays emanating from lights. These phenomena can occur due to corneal swelling during the initial healing period, or if the pupil dilates larger than the treated area of the cornea. While these experiences may occur, they typically diminish significantly within weeks or months as the eye continues to heal.