Aims To report on the influence of rigid gas permeable contact lens (CL) wear on the results of ultraviolet A/riboflavin cross-linking (CXL) for stabilisation of progressive keratoconus.

Methods Prospective non-comparative study of 15 eyes without CL and 12 eyes fitted with CL from 1 to 10 weeks post-CXL. None of the patients had been wearing CL before CXL. The effect of the CXL treatment was measured by the change from the baseline of best spectacle corrected visual acuity (BSCVA), refractive sphere and cylinder, maximal keratometry value (K max), simulated keratometry steep, flat, astigmatism, refractive power (RP) steep, flat and astigmatism, I-S value on EyeSys (EyeSys Vision Inc, Houston, Texas, USA) and K max on Pentacam (Oculus Optikgeräte, Wetzlar, Germany). The results of these measurements are reported pre-CXL and at 6-month intervals up to 18 months post-CXL.

Results In the eyes without CL, none of the study parameters showed a significant change from baseline. Only in the group of eyes fitted with CL post-CXL, several parameters showed a significant improvement: I-S value and K max on EyeSys (all time points), RP steep and simulated astigmatism (6 and 12 months) and RP flat (12 months).

Conclusion CL can be a confounding factor in interpreting the results of CXL: lens wear itself leads to improved topographic parameters.