Keratoconus is a degenerative, hereditary corneal disease that usually occurs on both eyes. It is characterized by the cone-like bulge and central cornel thinning. Keratoconus usually occurs during puberty and about 20 percent of patients have the disease so advanced that surgical treatment (corneal transplantation) is necessary. Simultaneously with the corneal thinning and deformation, the diopter increases and the visual acuity decreases.
By applying semi-rigid contact lenses, an attempt to stabilize the deformed cornea, improve visual acuity and slow down the development of the disease is made. If the disease progresses, further thinning and deformity occur, and the scar-like changes in the central cornea begin to appear.
Cross linking is a procedure to strengthen the cornea and prevent further progression of keratoconus. Holding collagen fibers together is made possible using riboflavin solution and UVA radiation. Thus, satisfactory corneal mechanical strength is formed which helps to prevent further deformation and halt the progression of keratoconus.
Cross linking is a photooxidative method. Before the UVA radiation, anesthetic drops are applied and then the cornea epithelium is partially removed to enhance the riboflavin diffusion into the corneal tissue.
Thereafter, a riboflavin solution is applied every 2 minutes during 20 minutes. Riboflavin absorbs UV radiation and serves as a photosensitizer to create reactive oxygen. Ninety percent of UV light is absorbed in the cornea so there is no risk of lens or retina damage.
The length of radiation is between 10 and 30 minutes depending on which protocol is used during the procedure. If the patient is a younger person with keratoconus progressing rapidly, the so-called Dresden protocol is applied and the drip and UV radiation are carried out for 30 minutes. For the elderly and those with more stable keratoconus, shorter radiation is applied. The procedure is completely painless.
After the procedure a soft contact lens is placed on the cornea as a protection and left during complete regeneration of the epithelial cornea layer, usually for a few days. Antibiotic eye drops are applied for two to three weeks, as well as painkillers, as needed.
Serious complications after keratoconus surgery using cross linking method have not been known so far. As transient side effects during the first weeks after surgery, redness of the eye, itching, choking and blurred vision may occur.