The purpose of a retrospective study was to evaluate topographic and tomographic changes in fellow eyes in unilateral keratoconus patients by comparing them with normal eyes. According to the study, which used Pentacam Scheimpflug imaging, keratometric asymmetry and topometric indices were best at discriminating fellow eyes from normal, followed by elevation differences on the posterior and anterior corneal surface. The authors concluded that fellow eyes in unilateral keratoconus patients exhibited differences in several parameters. However, each single parameter alone is not sufficient to detect early changes; thus, elevation indices as well as indices of anterior curvature should be considered together.  

Maybe one of the best reports on corneal cross-linking (CXL) to date is a recent paper in the January 2014 Ophthalmology. In a randomized, controlled trial, the refractive, topographic, and clinical outcomes are reported three years after CXL was performed in eyes with progressive keratoconus. At 36 months after treatment, there was a sustained improvement in maximum simulated keratometry value, uncorrected visual acuity, and best spectacle-corrected visual acuity, whereas eyes in the control group demonstrated further progression. In Optometry & Vision Science, Johannes Steinberg et al look at elevation maps post-CXL. While the elevation of the front surface at the apex decreased, the back elevation at the apex increased. Although not reaching statistical significance, the maximum front and back elevation demonstrated the same trend; while maximum front elevation data remained stable, maximum back elevation data increased. As a result of this, corneal thickness at the apex decreased by about 22 microns.Conclusions: increasing posterior elevation values, despite a stabilized anterior corneal surface, might be a sign of ongoing ectatic changes in the posterior corneal surface.