Refractive, Topographic, Tomographic, and Aberrometric Analysis of Keratoconic Eyes Undergoing Corneal Cross-linking

Purpose: To report refractive, topographic, tomographic, and aberrometric outcomes 12 months after corneal cross-linking (CXL) in eyes with progressive advanced keratoconus.

Design: Prospective, nonrandomized, single-center clinical study.

Participants: Twenty-eight eyes undergoing CXL between April and June 2006.

Intervention: Riboflavin-ultraviolet A (UVA)-induced CXL included instillation of 0.1% riboflavin-20% dextrane solution 30 minutes before UVA irradiation and every 5 minutes for an additional 30 minutes during irradiation.

Main Outcome Measures: Uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), sphere and cylinder refraction, topography, tomography, aberrometry, and endothelial cell count were evaluated at baseline and at 1, 3, 6, and 12 months follow-up.

Results: Mean baseline UCVA and BSCVA were 0.17+/-0.09 and 0.52+/-0.17, respectively; 12-month mean UCVA and BSCVA were 0.27+/-0.08 and 0.72+/-0.16, a statistically significant difference (P<0.05). Mean spherical equivalent refraction showed a significant decrease of 0.41 diopters (D). Mean baseline simulated keratometry (SIM K) flattest and steepest meridians and SIM K average were 46.10, 50.37, and 48.08 D, respectively; at 12 months, 40.22, 44.21, and 42.01 D, respectively, were recorded, a difference that was significant for all 3 indices (P<0.05). Mean average pupillary power (APP) changed significantly from 47.50 to 41.04 D at 12 months (P<0.05) and apical keratometry (AK) from 58.94 to 55.18 D (P<0.05). The treated eyes showed no deterioration of the Klyce indices at 6 months postoperatively, whereas the untreated (contralateral) eyes did show deterioration. For a 3-mm pupil, there was a significant reduction (P<0.05) in whole eye (total), corneal, higher order, and astigmatic wavefront aberrations. A significant difference (P<0.05) in total coma and total spherical aberration after CXL was also observed. Mean baseline pupil center pachymetry and total corneal volume decreased significantly (P<0.05) to 470.09+/-29.01 microm and 57.17+/-3.21 mm(3) from baseline values of 490.68+/-30.69 microm and 59.37+/-4.36 mm(3), respectively. Endothelial cell counts did not changed significantly (P=0.13).

Conclusions: Corneal cross-linking seems to be effective in improving UCVA and BSCVA in eyes with progressive keratoconus by significantly reducing corneal APP, AK, and corneal and total wavefront aberrations at 1 year postoperatively.