Treatment

The treatment of keratoconus is based upon the severity of the condition in the individual and the rate of progression of the disorder. In some individuals with mild symptoms, vision may be improved with the use of appropriate eyeglasses or soft contact lenses. However, progressive changes in vision often necessitate frequent prescription changes.

In many individuals, rigid gas permeable contact lenses (a modern version of ‘hard’ contact lenses) may be required. These lenses can reshape the corneal surface to hide or mask the underlying cone-shaped defect of the cornea. In some individuals, these contact lenses may become uncomfortable and are not tolerated well. In such cases, individuals can use ‘piggyback’ contacts lenses in which hard contact lenses are placed over soft lenses. The underlying soft lenses provide comfort and support, while the hard lenses improve vision. Other types of contact lenses that may be used include hybrid lenses, which have a rigid center and soft ring on the outside, or scleral lenses, which are larger traditional contact lenses and which rest atop the sclera (the whites of the eyes) and mount above the cornea.

However, some severely affected individuals may not be able to wear contact lenses due to progressively severe corneal thinning, corneal scarring, and/or contact intolerance. In cases of severe visual deterioration in which contact lenses cannot sufficiently correct vision or are not tolerated, surgery may be required such as intracorneal ring segments or a corneal transplant (keratoplasty).

In 2004, the U.S. Food and Drug Administration approved intracorneal ring segments for the treatment of individuals with keratoconus. During this procedure, two, tiny crescent-shaped plastic pieces are inserted into the cornea. These inserts can help to flatten, strengthen, and support the cornea and improve vision. Typically, eyeglasses or contact lenses are still required for proper vision.

In 2016, the U.S. Food and Drug Administration granted the first approval of a collagen cross-linking device to treat progressive keratoconus. This device, the Avedro KXL, uses UV light and riboflavin formulations to strengthen the cornea.

A corneal transplant is a surgical procedure in which abnormal corneal tissue is removed and replaced with healthy donor corneal tissue. This surgery is generally reserved for individuals with severe disease (e.g. the cornea is extremely thin and/or vision is significantly compromised) or who cannot tolerate or did not respond to more conservative treatments. A corneal transplant may also be indicated after an episode of corneal swelling (corneal hydrops) that does not respond to other treatment options. There are several different corneal transplant procedures that may be used. Corneal transplants are generally effective for treating individuals with keratoconus, but do carry a small risk of complications, including rejection of the donated tissue by the body (graft rejection). Of note, individuals who have a corneal transplant typically still need hard contact lenses after the transplant because the cornea, while flatter, still does not have a perfect shape.

Preventative Therapies

A procedure known as corneal collagen cross-linking (CXL) has been used to successfully treat individuals with keratoconus. This procedure uses ultraviolet A (UVA) light and riboflavin, a type of B vitamin, to slow or halt the progression of keratoconus. During the procedure, riboflavin is placed on the cornea via eye drops. Riboflavin acts as a photosensitizer, which allows corneal tissue to absorb the ultraviolet light. Basically, this procedure creates new bonds in the collagen of the cornea, strengthening the cornea and halting progression. In some cases, the cornea obtains a flatter shape after CXL, but it does not return to ‘normal’ entirely.

A procedure known as topography-guided photorefractive keratectomy has been combined with collagen cross-linking to treat some individuals with mild to moderate keratoconus. Photorefractive keratectomy is a type of laser eye surgery that is most often used to treat individuals with mild or moderate nearsightedness, farsightedness or astigmatism. Generally, laser surgery is not recommended (contraindicated) for individuals with keratoconus. During this procedure a laser is used to reshape the affected cornea(s). More research is necessary to determine the long-term safety and effectiveness of this potential procedure for specific individuals with keratoconus.