Collagen Crosslinking for Keratoconus can Change Scleral Shape
DeNaeyer G1, Sanders DR2
1 Optometrist at Arena Eye Surgeons, USA
2 Center for Clinical Research and President and CEO, Visionary Optics LLC, USA
Collagen crosslinking (CXL) for keratoconus is known to decrease, halt, or even partially reverse progres-sion of keratoconus. We report on a case where a substantial effect on scleral shape was also demonstrated. This keratoconus patient, who was successfully wearing a scleral lens, underwent collagen crosslinking OS. Three-months post crosslinking, the patient was unable to wear his previous scleral lens due to lens discomfort. Elevation mapping pre and post crosslinking, with a new corneal-scleral topography system, showed a decrease in size and change in shape of the cone, as well as a substantial change in the scleral elevation pattern at a 16-mm chord diameter. The change in the scleral elevation pattern was best observed on scleral shape plots which graph the sagittal height (SAG) value on the Y-axis vs. meridian on the X-axis. The pre-crosslinking plot resembled a standard toric curve although the depression inferiorly at 327° was deeper than that superiorly by >250µ. The post-crosslinking plot changed substantially with the steep axis superiorly being markedly attenuated: the SAG superiorly (106°) decreased post-crosslinking by >350µ. Attempts to virtually fit the eye surface post-crosslinking with a standard posterior toric haptic demonstrated a good fit superiorly and a poor fit inferiorly. The post-crosslinking scleral toricity plot was used to obtain quantitative information to manufacture a custom design conforming to this specific eye. The resulting lens was comfortable, well centred and resulted in a BCVA of 20/30.