الفهرس 
IntroductionOnly 14 pages are availabe for public view
 |  | from | 103 |  |  |
| | | from | 103 | | |
Abstract
Keratoconus is a progressive, non-inflammatory, bilateral (but usually asymmetrical) disease of the cornea, characterized by paraxial stromal thinning that leads to corneal surface distortion. Visual loss occurs primarily from irregular astigmatism and myopia and secondarily from corneal scarring.
The pathological process as shown in a number of studies have indicated that keratoconic corneas show signs of increased activity by proteases, a class of enzymes that break some of the collagen cross-linkages in the stroma, with a simultaneous reduced expression of protease inhibitors. This results in a reduction in the corneal thickness and biomechanical strength.
Although advanced keratoconus can be clinically diagnosed via history and examination, however the diagnosis is challenging in its early stages, and may necessitate the use of corneal topography to confirm the diagnosis.
Corneal topography became a milestone in the diagnosis and follow up of eyes with keratoconus with and without treatment. Two generations have been in use, placido disc based corneal topography (curvature based topography) and the new and the more precise elevation based corneal topography.
Different recent modalities of treatment have been used for keratoconus treatment. Among these modalities were corneal collagen cross linking.
Summary
-75-
Corneal Collagen Crosslinking with Riboflavin, also known as CXL, CCL or C3-R, has shown success in early cases of keratoconus. Application of riboflavin solution on the cornea then its activation by illumination with UV-A light for approximately 30 minutes. The riboflavin causes new bonds to form across adjacent collagen strands in the stromal layer of the cornea. This process recovers and preserves some of the cornea’s mechanical strength.
Early results are very promising as stabilization is achieved in almost all treated eyes, and a slight correction in visual acuity in most patients.