The Impact of Standard Cross-Linking on the Corneal Optical Density-Age Relationship in Keratoconus After Mechanical Stripping of the Epithelium.

To determine if cross-linking (CXL) treatment modifies any pre-existing association between corneal optical density (COD) and age in keratoconus free of corneal scarring. COD was monitored in two groups (i) before and after standard CXL treatment for keratoconus (de-epithelization with a crescent blade,  = 69 eyes) and (ii) age/gender-matched cases without any signs of keratoconus ( = 24 eyes). Seven different markers of COD were quantified using a 0-100 grey scale, supplied with Pentacam™ software. Mean age (±sd, range) in Group I (19 females and 50 males) was 24.2 years (±7.2, 11-44) and in Group II (9 females and 15 males), it was 24.7 years (±7.6, 17-45). COD over the apex and along the depth of the cornea (y, arbitrary scale units) was associated with age (, in years) in Group I at preop ( = 0.08 + 13.12,  = 0.350 and =0.003), at 12 months postop ( = 0.08 + 15.15,  = 0.295 and =0.014) and in Group II, at the start ( = 0.16 + 11.28,  = 0.474 and =0.019) and 12 months later ( = 0.24 + 8.63,  = 0.600 and =0.002). The change in COD following CXL was significantly associated with the preop value. CXL initially breaks down the pre-existing relationship between COD and age. This is re-established by 12 months postop. The CXL induced change in COD depends on the preop value but not on the patient's age.