LASIK (Laser-Assisted In Situ Keratomileusis) is a common refractive surgery that corrects vision problems like nearsightedness, farsightedness, and astigmatism. Astigmatism is an imperfection in the eye’s curvature, often in the cornea or lens, causing blurred or distorted vision. LASIK for astigmatism reshapes the eye’s surface to improve clarity and reduce reliance on corrective eyewear.
How LASIK Corrects Astigmatism
LASIK corrects astigmatism by precisely reshaping the cornea, the eye’s clear, dome-shaped front surface. An excimer laser emits cool, ultraviolet light to remove microscopic amounts of corneal tissue. This reshaping alters how light enters the eye, allowing it to focus properly on the retina.
Before the laser treatment, a thin, hinged flap is created on the corneal surface, using either a specialized blade or another laser. This flap is then gently lifted to expose the underlying corneal tissue. The excimer laser then applies its precise reshaping, creating a more spherical and uniform surface to correct the irregular curvature of astigmatism.
Once the cornea has been reshaped, the flap is carefully repositioned, where it naturally adheres without the need for stitches. The changes made to the corneal tissue at the cellular level are permanent and do not revert. This alteration is why the initial correction of astigmatism by LASIK is considered long-lasting.
Expected Durability of Astigmatism Correction
For most individuals, the astigmatism correction achieved through LASIK is considered permanent, as the corneal reshaping performed by the laser does not “wear off” or revert over time. The physical changes made to the eye are designed to last a lifetime.
Studies have shown high rates of success and long-term stability for LASIK outcomes. Many patients maintain their improved vision for many years, even decades, following the procedure. A significant percentage of patients achieve 20/20 or 20/40 vision, reducing or eliminating their need for glasses or contact lenses.
While the corneal reshaping itself is permanent, it is important to understand that a person’s eyes can still undergo natural changes over time. These changes are typically due to the aging process or other factors unrelated to the LASIK procedure itself. Therefore, while the correction of astigmatism is stable, vision may still evolve for other reasons.
Reasons for Vision Changes Over Time
Although the corneal changes from LASIK are permanent, vision can still change over time due to factors distinct from the initial procedure. The most common reason for vision changes years after LASIK is the natural aging process of the eye. One such age-related condition is presbyopia, which typically begins after age 40. This involves the natural lens inside the eye becoming less flexible, making it difficult to focus on nearby objects. LASIK corrects issues with the cornea and does not prevent presbyopia, as it does not affect the eye’s internal lens.
Another age-related condition that can affect vision is the development of cataracts. Cataracts occur when the eye’s natural lens becomes cloudy, leading to blurred or hazy vision. LASIK does not cause cataracts; they are a natural part of the aging process and can develop in anyone, regardless of whether they have had LASIK.
In some infrequent cases, vision changes might involve a small amount of residual astigmatism or a slight regression of the initial correction. This is distinct from the LASIK “wearing off” and refers to the eye settling or a minor, uncorrected refractive error remaining after the initial surgery. Such occurrences are generally minor and can often be addressed.
Options for Sustaining or Improving Vision
If vision changes occur after LASIK, several options are available to help sustain or improve visual clarity. For individuals experiencing a small amount of residual refractive error or a slight return of astigmatism, an enhancement procedure may be an option. This retreatment involves lifting the original corneal flap and using the laser to perform a minor additional reshaping. Eligibility for an enhancement depends on factors such as corneal thickness and overall eye health.
For age-related presbyopia, standard reading glasses can provide clear near vision. Another surgical option is monovision LASIK, where one eye is corrected for distance vision and the other is intentionally left slightly nearsighted for close-up tasks. This approach can reduce or eliminate the need for reading glasses, though it requires an adjustment period for the brain to adapt.
Should cataracts develop, cataract surgery is a safe and effective treatment. This procedure involves removing the cloudy natural lens and replacing it with an artificial intraocular lens (IOL). Cataract surgery can be performed safely after previous LASIK, and advanced IOLs can often correct vision, including astigmatism, at the same time.