T-Cat Laser & Cross-linking for Keratoconus

Theoretical framework: Corneal ectasia is a relative weakness in the structure of the cornea, which produces a progressive change in its shape with resultant visual distortion. Excimer laser surface ablation can be used to re-shape the corneal profile. When the corneal shape is very irregular, corneal topography data gives the best information as to how to re-shape the cornea into a normal profile, and this Topography-Computer Assisted Treatment (T-Cat) will be used to modulate the surface corneal shape. It is known that collagen cross-linking in the cornea occurs naturally with age, and in diabetes, both of which seem to prevent progressive ectasia. Corneal collagen cross-linking with riboflavin has been shown to stabilize the cornea in keratoconus, and prevents progression of the disease. If cross-linking is performed at that moment that the cornea has been re-shaped by T-Cat treatment, it should help prevent the corneal thinning resultant from the laser treatment from destabilising the cornea and causing progressive ectasia. Purpose: To determine whether excimer laser corneal surface ablation (T-Cat) can be safely combined with simultaneous corneal collagen cross-linking treatment to produce an improved and stable corneal profile. Design: Prospective, interventional trial.