Spatial distribution of corneal light scattering after corneal collagen crosslinking

PURPOSE: To assess the spatial distribution and time course of increased corneal light scattering after corneal collagen crosslinking (CXL) with riboflavin and ultraviolet-A irradiation. SETTING: Umea University Hospital Eye Clinic, Umei, Sweden. DESIGN: Case series. METHODS: Eyes with keratoconus were examined with Scheimpflug photography before and 1 and 6 months after CXL. Corneal light scattering was quantified throughout the corneal thickness at 8 measurement points 0.0 to 3.0 mm from the central cornea. RESULTS: The study comprised 11 eyes of 11 patients. Central corneal light scattering increased significantly 1 Month after CXL (P<.001). At 6 months, it decreased (P=.002); however, it was still higher than pretreatment values (P<.001). Light scattering at 1 month was more pronounced in the superficial stroma, gradually diminishing to zero at 240 pm depth. It was greater at the corneal center than 1.0 to 3.0 mm from the center. At 6 months, a second peak of light scattering occurred between 240 mu m and 340 mu m depth. No increased light scattering deeper than 340 pm was seen at either time point. CONCLUSIONS: Corneal light scattering after CXL showed distinctive spatial and temporal profiles. Analysis of corneal light scattering may give an impression of tissue changes, the depth of the CXL treatment effect, and the corneal response to the treatment. Scheimpflug photography appears to be useful for this purpose.