Topo-Aberrometric, Refractive and Pachymetric Analysis of Keratoconic Eyes Undergoing Corneal Cross Linking: Intra- and Postoperative Findings at 1 Year Follow-Up

Abstract

Purpose: : To report the intraoperative and the 12-month topo-aberrometric, refractive and pachymetric outcomes after corneal cross linking (CCL) in eyes with progressive advanced keratoconus (KC).

Methods: : Prospective, non randomized clinical controlled study including 28 patients undergoing riboflavin/UVA cross linking procedure.

Results: : Mean baseline UCVA and BSCVA were 0.17±0.09 and 0.52±0.17 respectively, and final mean UCVA and BSCVA were 0.27±0.08 and 0.72±0.16, a statistically significant difference (P<0.05). Mean refraction showed a significant reduction of spherical equivalent of 0.41D. Comparison of endothelial cell count changes before CCL and at 12 months showed no significant difference (P=0.13). Mean baseline SIM K flattest meridian, SIM K steepest meridian and SIM K average were 46.10 D, 50.37 D, 48.08 D respectively, and 40.22 D, 44.21 D and 42.01 D at 12 months, a difference that was statistically significant for all three indices (P<0.05). Mean average pupillary power (APP) and apical keratometry (AK) changed significantly from 47.50 D to 41.04 D and from 58.94 D to 55.18 D at 12 months (P<0.05). Mean baseline pupil center pachymetry and total corneal volume decreased significantly (P<0.05) at 470.09±29.01µm and 57.17±3.21 mm³ respectively from baseline values of 490.68±30.69 µm and 59.37±4.36 mm³. At 3 mm we observed a significant reduction (P<0.05) in total, high order and astigmatic total and corneal wavefront aberrations measured by Optical Path Difference Platform (NIDEK, Gamagori, Japan) and a significant difference in total coma and total spherical aberration after CCL (P<0.05). After the 6^th postoperative month, there was a slow but continuous improvement of Klyce KC indces probably because of corneal remodelling. The treated eyes showed no progression of Klyces KC indices, while the controlateral (untreated) eyes showed that the indices tended to progress slowly.

Conclusions: : CCL appears to be effective in improving UCVA and BSCVA in eyes with progressive KC by significantly reducing corneal APP, AK and total and corneal wavefront aberrations at one year follow-up.

Keywords: keratoconus • topography • refractive surgery: other technologies