Laser treatment for farsightedness is accomplished using a different sculpting pattern than for nearsightedness. For nearsighted corrections, the laser sculpts to flatten the central cornea; for farsighted corrections the central corneal radius must be steepened.
In part because the sculpting pattern is different for near-and farsightedness correction, and in part because the natural biology of healing is slightly different, the outcomes achieved in these two groups are different as well. Results for farsightedness treatment are not quite as stellar as they are for nearsightedness. For details, see our LASIK Results at LA Sight page.
Laser treatment for nearsightedness affords visual results that are remarkably clear within hours of treatment, and that remain stable over long periods of time. The correction achieved is retained for many years or decades. Visual results after farsighted treatment are not always optimally sharp within hours; sometimes vision can be initially blurry, taking days or even weeks to become optimal. In very rare cases, temporary glasses may be necessary after farsighted LASIK treatment, to obtain comfortable distance (driving) vision. The natural biology of healing after farsighted correction is different than after nearsighted correction, and a significant percentage of patients treated for farsighted correction do experience some loss of the treatment effect (also called “regression”) over time. This can lead to an increased likelihood of imperfect vision some months or years out after initial or primary surgery; therefore, enhancement or “touch-up” incidence is significantly higher after farsighted LASIK treatment than after nearsighted LASIK. This is primarily thought to be due to filling in of the sculpted groove (annulus or circular channel) by the surface lining cells of the cornea, called the epithelium. It is not possible to anticipate or perfectly control the process of epithelial healing, or filling-in, after farsighted treatment. In some cases, patients treated for moderate to high amounts of farsightedness can require two, three or perhaps even four enhancements over a multi-year period.
With or without enhancement, some patients experience a loss of best-corrected acuity after farsighted LASIK, such that they cannot easily read the smaller letters on the standard Snellen eye chart. After farsighted treatment, the resultant corneal curvature is altered such that future care with cataract and lens implant surgery may be adversely affected. Farsightedness correction also is associated with an increased likelihood of glare and halo around point sources of light, that can adversely affect night vision and night driving, which is much less likely with nearsighted correction.