Purpose: To study the effect of Riboflavin and ultraviolet A induced collagen cross linking (CXL) in keratoconus and post-LASIK ectasia . Subjects and Methods:- Twenty four eyes of twenty three patients undergoing collagen cross-linking, measurements at 1, 3, 6, 9, and 12 month after corneal cross linking were: Best corrected visual acuity (BCVA), slit lamp examination, the Oculyzer for detecting K readings, anterior and posterior elevations maps, corneal volume, keratoconus indices, and abrasion coefficient. Optical coherence tomography (OCT.), for detecting foveal thickness. Results:- Mean preoperative BCVA was 0.5 ± 0.23. At 12 months the mean BCVA was 0.63 ± 0.22, with a statistically significant difference (P