Keratoconus is a progressive eye disease affecting the cornea, the clear, dome-shaped front surface of the eye. While no true “cure” reverses the underlying biological cause, modern treatments effectively manage the disease and halt its progression. These interventions prevent the severe vision loss that was once common, allowing most patients to maintain functional vision. Treatment focuses first on stabilizing the cornea and then on restoring clear vision using specialized optical aids and surgical options.
What Keratoconus Is and How It Is Diagnosed
Keratoconus is a disorder where the normally smooth, rounded corneal tissue thins and bulges outward into a cone shape, a process known as ectasia. This change causes the eye’s primary focusing surface to become irregular, leading to distorted vision. The condition typically begins during the late teenage years or early twenties and progresses slowly for ten to twenty years before stabilizing.
The precise cause of keratoconus is not fully understood, but it involves a combination of genetic predisposition and environmental factors. Symptoms include a gradual worsening of vision, increased sensitivity to light (photophobia), and glare or halos around lights, often making night driving difficult. Patients may also experience frequent changes in their eyeglass prescription as the cornea’s shape shifts.
Diagnosing the condition relies on a comprehensive eye exam, with the definitive confirmation coming from an imaging test called corneal topography. This non-invasive test creates a detailed, three-dimensional map of the cornea’s curvature and shape, allowing an eye care professional to visualize the cone-like distortion and monitor its progression. Early detection is paramount, as intervening when the disease is still progressing offers the best long-term outcome.
Treatments Designed to Halt Progression
The most significant advance in managing keratoconus is the ability to stop the disease from worsening through a procedure called Corneal Collagen Cross-Linking (CXL). CXL is the only treatment approved to strengthen the cornea and halt progressive thinning and bulging. The procedure works by creating new, stronger bonds between the collagen fibers within the corneal layer, stiffening the tissue to prevent further deformation.
The process involves applying a solution containing riboflavin (Vitamin B2) drops, which acts as a photosensitizer. The cornea is then exposed to controlled ultraviolet-A (UVA) light. This combination initiates a photochemical reaction that increases the number of collagen cross-links. The original and most common technique, known as “epi-off” CXL, requires removing the cornea’s thin outer layer (epithelium) to allow deeper riboflavin penetration.
A newer approach, “epi-on” CXL, leaves the epithelium intact, leading to less post-operative pain and faster recovery. However, riboflavin absorption may be less efficient, requiring longer application times or specialized solutions. While CXL is highly effective at stabilizing the condition, the procedure does not reverse existing vision loss or fully correct the corneal shape. Its primary purpose is preventative.
Restoring Vision After Stabilization
Once keratoconus has stabilized, the focus shifts to correcting the vision distortion caused by the irregular corneal shape. Standard eyeglasses or soft contact lenses are often insufficient because they conform to the irregular cornea and cannot fully correct the resulting astigmatism. Specialized contact lenses are the primary way to restore clear vision for most patients.
Rigid Gas Permeable (RGP) lenses are often used because they hold their shape, creating a new, smooth refractive surface over the irregular cornea. Scleral lenses are an increasingly successful option; they are much larger, vault entirely over the cornea, and rest on the sclera. This design minimizes discomfort and provides a constant layer of fluid between the lens and the cornea, offering superior visual clarity.
For moderate cases where vision correction with lenses is challenging, small, crescent-shaped plastic inserts called Intacs may be surgically placed within the peripheral cornea. These implants work by physically reshaping and flattening the steepened part of the cornea, which can significantly improve vision and make wearing contact lenses more comfortable. Intacs are often used to reduce the severity of the cone and potentially delay the need for a corneal transplant.
When the disease is severe, resulting in significant corneal scarring or thinning that cannot be corrected by lenses or other procedures, a corneal transplant (keratoplasty) may be necessary. A full-thickness transplant, known as Penetrating Keratoplasty (PK), replaces the entire central cornea with healthy donor tissue. Alternatively, a partial-thickness procedure like Deep Anterior Lamellar Keratoplasty (DALK) replaces only the diseased front layers, preserving the patient’s own healthy inner layer, which can reduce the risk of graft rejection. Transplants are considered a last resort, but they offer a high success rate in restoring sight.