Farsightedness, medically termed hyperopia, is a common refractive error where light entering the eye focuses behind the retina instead of directly on its surface. This occurs because the eyeball is either shorter than average or the cornea, the eye’s clear front window, possesses a flatter curvature. The result is that objects at close range appear blurry. Modern ophthalmology offers a range of options to correct this focusing error, from external lenses to advanced surgical procedures that can provide a permanent alteration to the eye’s structure.
Non-Surgical Correction with Lenses
The most common and least invasive method for correcting hyperopia involves the use of external lenses, specifically eyeglasses or contact lenses. These corrective devices work by adding optical power to the eye’s visual system, effectively shifting the focal point forward onto the retina. This required additional power is measured in diopters and is achieved using a convex, or plus-powered, lens.
A convex lens is thicker in the center and tapers toward the edges, causing light rays to converge before they enter the eye. This pre-convergence compensates for the eye’s insufficient focusing power, allowing a clear image to form on the retina. While convenient and effective, this approach is a temporary solution, as the hyperopia remains and the vision correction ceases immediately upon the lenses’ removal.
Permanent Modification via Laser Procedures
For those seeking a long-term solution, laser procedures offer a way to permanently reshape the cornea to correct the refractive error. These surgeries aim to steepen the central curvature of the cornea, which increases the eye’s overall converging power. Laser-Assisted In Situ Keratomileusis (LASIK) and Photorefractive Keratectomy (PRK) are the two primary techniques used for this permanent modification.
LASIK
In LASIK, a surgeon first creates a thin, hinged flap in the outer layer of the cornea using a specialized laser. The flap is gently lifted, and an excimer laser is then used on the underlying tissue to precisely ablate microscopic layers of tissue in a peripheral ring pattern. This peripheral ablation causes the central cornea to become steeper. The flap is then repositioned to complete the procedure, which is known for its rapid recovery time and minimal discomfort.
PRK
PRK is an alternative for people who may not be candidates for LASIK, often due to thinner corneas. Instead of creating a flap, the outer protective layer of the cornea, called the epithelium, is completely removed. The excimer laser then reshapes the underlying corneal tissue to induce the necessary steepening. The epithelium grows back naturally over the next few days, conforming to the cornea’s new shape, although the initial healing is associated with a longer, more uncomfortable recovery period compared to LASIK. Both procedures are approved for corrections up to approximately +6.00 diopters, with the best results often seen in corrections of +4.50 diopters or less.
Surgical Lens Replacement Options
When laser surgery is not a suitable option, particularly for higher degrees of hyperopia or in older individuals, surgical options involving the internal structures of the eye provide a permanent alternative. These procedures focus on either replacing the eye’s natural lens or implanting a supplementary lens.
Refractive Lens Exchange (RLE)
Refractive Lens Exchange (RLE) is a procedure essentially identical to modern cataract surgery, but it is performed on a clear lens rather than a cloudy one. The natural lens, which has insufficient focusing power, is removed through a micro-incision and replaced with an artificial intraocular lens (IOL) customized to correct the farsightedness. RLE can correct virtually any degree of hyperopia and is often recommended for individuals over the age of 45 who are beginning to experience age-related focusing issues, known as presbyopia. This replacement also eliminates the possibility of developing a cataract in the future.
Implantable Collamer Lens (ICL)
Another lens-based option is the Implantable Collamer Lens (ICL), also known as a phakic intraocular lens. The ICL is a biocompatible lens surgically inserted into the eye, typically placed between the iris and the natural lens, without removing the natural lens. This procedure is often preferred for younger adults who have a high refractive error that falls outside the treatable range for laser surgery, or for those with thin corneas. Unlike RLE, ICL surgery preserves the natural lens, which retains the eye’s ability to change focus.