Long-term evaluation of posterior corneal surface parameters after accelerated corneal cross-linking with a...

To evaluate the 36 months changes in posterior corneal surface parameters in keratoconic eyes after accelerated corneal cross-linking and to compare the data with uncross-linked progressive and non-progressive keratoconic eyes.

Thirty five cross-linked, 30 uncross-linked progressive, and 30 uncross-linked non-progressive keratoconic eyes were included. Maximum keratometry (K_max), thinnest pachymetry, minimum radius of curvature back (R_minback), asphericity back, posterior elevation and corneal densitometry, back corneal higher order aberrations (HOAs), back surface deviation (Db), final D, posterior radius of curvature (PRC) and 'B' unit values were recorded at baseline and at the 12, 24, 36 months follow-up. Data were analyzed with repeated measures ANOVA and paired t-tests.

K_max and thinnest pachymetry were significantly changed in the cross-linked and progressive uncross-linked groups. R_minback, asphericity back, and HOAs did not change in either group. Total posterior corneal densitometry improved; posterior elevation, Db and B unit worsened in the cross-linked group and did not change in the uncross-linked groups. PRC and final D worsened in the cross-linked and progressive uncross-linked groups, and did not change in the non-progressive group.

Despite a decreased K_max, the posterior corneal surface parameters, posterior elevation values were determined to have significantly worsened in the cross-linked group and this increase was higher than in progressive uncross-linked eyes.