Initial results from mechanical compression of the cornea during crosslinking for keratoconus

PurposeTo compare refractive changes after corneal crosslinking with and without mechanical compression of the cornea. MethodsIn a prospective, open, randomized case-control study conducted at the Department of Ophthalmology, Umea University Hospital, Sweden, sixty eyes of 43 patients with progressive keratoconus aged 18-28years planned for corneal crosslinking and corresponding age- and sex-matched control subjects were included. The patients were randomized to conventional corneal crosslinking (CXL; n=30) or corneal crosslinking with mechanical compression using a flat rigid contact lens sutured to the cornea during treatment (CRXL; n=30). Subjective refraction and ETDRS best spectacle-corrected visual acuity (BSCVA), axial length measurement, keratometry and pachymetry were performed before and 1 and 6months after treatment. ResultsThe keratoconus patients had poorer BSCVA, higher refractive astigmatism and higher keratometry readings than the control subjects at baseline (p<0.01). In the CXL group, BSCVA increased from 0.190.26 to 0.14 +/- 0.18 logMar (p=0.03), and the spherical equivalent improved from -1.9 +/- 2.8D to -1.4 +/- 2.4D (p=0.03). Maximum keratometry readings decreased after CXL from 53.1 +/- 4.9D to 52.6 +/- 5.2D (p=0.02), and the axial length decreased in the CXL group, likely due to post-treatment corneal thinning (p=0.03). In the CRXL group, all the above variables were unaltered (p>0.05). ConclusionAt 6months, the refractive results from CRXL did not surpass those of conventional CXL treatment. Rather, some variables indicated a slightly inferior effect. Possibly, stronger crosslinking would be necessary to stabilize the cornea in the flattened configuration achieved by the rigid contact lens.