Farsightedness (hyperopia) is a common condition where the eye focuses light incorrectly. This occurs because the eyeball is slightly too short or the cornea is too flat, causing light to focus behind the retina instead of directly upon it. This typically results in blurry vision for close-up objects. Laser-Assisted In Situ Keratomileusis (LASIK) is a surgical procedure that corrects this refractive error by reshaping the cornea.
How LASIK Corrects Farsightedness
LASIK corrects hyperopia by steepening the curvature of the central cornea, which is the opposite technique used for nearsightedness. The excimer laser removes tissue in a precise ring shape around the cornea’s mid-periphery. This annular ablation pattern causes the central part of the cornea to bulge forward slightly.
The resulting steeper central curvature increases the eye’s overall focusing power. This shifts the focal point of the light rays forward, causing them to land correctly on the retina. Adjusting the cornea’s shape effectively shortens the light’s path within the eye’s optical system.
Determining Candidacy and Prescription Limits
Candidacy for hyperopic LASIK is often determined by stricter criteria compared to the treatment of nearsightedness. A candidate must have a stable prescription, typically one that has not changed significantly for at least 12 months. Sufficient corneal thickness is also a major factor, as the hyperopic correction requires the removal of tissue in the peripheral region of the cornea.
Prescription limits for hyperopia are generally more conservative. Most surgeons limit the treatment range to approximately +4.00 to +5.00 diopters (D). Outcomes become less predictable and stable at higher levels, such as +6.00 D. Treating stronger farsightedness is challenging because it requires a larger area of peripheral tissue removal, which strains the cornea’s structural integrity.
Specific Visual Outcomes and Risk of Regression
Correcting hyperopia with LASIK involves creating a larger ablation zone than is needed for nearsightedness, which introduces unique post-operative considerations. The expanded treatment area and the nature of the steepening procedure can increase the potential for certain visual symptoms. Patients sometimes experience increased night glare, halos around lights, or a temporary reduction in contrast sensitivity, particularly in the initial healing period.
A significant concern specific to hyperopic LASIK is the higher likelihood of regression, where the corrective effect gradually fades over time. This regression is largely driven by the cornea’s natural healing response, known as epithelial remodeling. The corneal epithelium tends to thicken over the area where the laser removed tissue, trying to normalize the artificial steepening. This biological response can partially undo the correction, leading to a return of farsightedness and sometimes requiring an enhancement procedure years later.
Alternative Treatments for Hyperopia
If a patient’s prescription is too high, their corneas are too thin, or their prescription is unstable, alternative surgical options exist.
One alternative is Photorefractive Keratectomy (PRK), a surface ablation technique that reshapes the cornea without creating a flap. PRK is a viable choice for individuals with thinner corneas, and its outcomes for hyperopia are comparable to LASIK, though recovery time is longer.
Refractive Lens Exchange (RLE) is a procedure similar to cataract surgery where the eye’s natural lens is replaced with an artificial intraocular lens (IOL). RLE is often recommended for older patients, typically those over 40 or 50, who have very high hyperopic prescriptions or are experiencing presbyopia.
For patients with extremely high prescriptions or thin corneas, Implantable Collamer Lenses (ICL) offer a reversible solution. The artificial lens is placed inside the eye without removing the natural lens.