Keratoconus is a disease of the cornea. The cornea is the clear window at the front of the eye which focuses light travelling through the eye onto the back of the eye (retina). In keratoconus, the shape of the cornea is cone-shaped rather than being spherical. This results in abnormal focusing of light as it travels through the eye leading to poor vision. Keratoconus is a disease which gets progressively worse with time, resulting in worsening of vision.
Corneal collagen cross-linking is a treatment performed on the cornea to strengthen the fibers (collagen) that comprise it. Roboflavin (vitamin B2) drops are applied to the cornea and the cornea is exposed to ultraviolet light (UVA). This causes a chemical reaction which results in chemical bonds (cross links) to form between the collagen fibers in the cornea. The results is that the cornea becomes stiffer and much less likely to get worse. There is very good evidence from large studies around the world that this is an effective treatment in stopping keratoconus progression.
The second stage of keratoconus treatment (once the progression has been stopped) is to improve the vision.
In keratoconus, the quality of vision achieved with glasses is unsatisfactory. In these cases, contact lenses have an important role. Specialised contact lenses are required in keratoconus because soft contact lenses cannot correct for the abnormal cone shaped cornea. There are several types of contact lenses that can be used including, rigid gas permeable lenses, hybrid lenses and scleral lenses. These contact lenses can be fitted by a contact lens specialist with expertise is fitting these lenses in eyes with keratoconus. They provide a spherical surface over the cone shaped cornea which allows light to be focused in a normal manner. The vision achieved is usually excellent.
In some severe cases of keratoconus, contact lenses may not be able to tolerated or may not provide satisfactory vision. In these cases, corneal transplantation becomes an option. The 2 types of corneal transplants performed for keratoconus are Deep Anterior Lamellar Keratoplasty (PK) and penetrating keratoplasty (PK).