Change in corneal microstructure with rigid gas permeable contact lens use following collagen cross-linking: an in vivo confocal microscopy study.

Aim: To study corneal microstructural changes with use of rigid gas permeable contact lenses (CLs) in keratoconus patients following collagen cross-linking (CXL).
Methods: In a prospective, non-randomised, comparative case series, keratoconus patients with documented progression were offered CXL (365 nm, 3 mW/cm(2), 30 min with 0.1% riboflavin). Patients who refused CXL were fitted with CL and followed up for 6 months (keratoconus (KL)-CL; 25 eyes). Patients who underwent CXL were either fitted with CL 3 months after the procedure (CXL-CL; 26 eyes) or followed up with only spectacle correction (CXL-SL; 21 eyes). Outcome measures of over-refraction and corneal microstructure (confocal microscopy) were evaluated at time of CXL and 1, 2, 3, 4, 6 and 9 months after CXL.
Results: There was a myopic shift in over-refraction by 0.37 D in CXL-CL (p=0.00), and 16/26 eyes required prescription of spectacles over CL to provide optimum vision; change in over-refraction was not seen in KC-CL. Patients using CL (CXL-CL and KC-CL) showed evidence of epithelial cell stress with increase in the superficial epithelial cell size and decrease in basal epithelial cell density. They also had a decrease in corneal sub-basal nerve plexus (CSNP) density and branching. Patients using spectacles after CXL showed regeneration of the sub-basal nerve plexus. Stromal keratocyte regeneration was unaffected with CL use.
Conclusions: CL use after CXL is associated with a delay in the regeneration of the CSNP and epithelial cell stress.