Abstract
Introduction: :
Objective: To evaluate wavefront aberrations following cornea collagen crosslinking (CXL) for keratoconus and ectasia.
Methods: :
Ocular aberrations were determined using the LADARWave (Alcon) in 26 eyes (25 patients), pre- and 1 year following CXL treatment (UVX; Peschke Meditrade GmbH) for KC (16 eyes) and ectasia (10 eyes). The Root Mean Square (RMS) was used to assess wavefront error for total higher order (3rd to 6th order) for both 4mm and 6.5mm pupil diameters. Independent analyses of vertical (Z7) and horizontal coma (Z8) components as well as spherical aberration (Z12) were also done. Wavefront refraction spherical equivalent (WRSE) and cylinder were analyzed before and after CXL along with MRSE. Uncorrected and best-corrected visual acuities were also recorded. Data analysis was carried out using PASW statistical software (SPSS Inc.).
Results: :
For all eyes, the mean RMS wavefront error decreased significantly following CXL for total higher order aberrations (3rd to 6th order) for both 4 and 6.5mm pupil diameters (p=0.044 and p=0.008). The mean change in RMS for 4mm was -0.25 (SD 0.436µm) and for 6.5 mm was -1.43 (SD 3.45µm) after CXL. Horizontal and vertical coma, remained unchanged following CXL while spherical aberrations were significantly decreased (mean change -0.08, p=0.01) for 6.5mm pupil diameter measurements. Comparison of WRSE pre- and 1 year postoperatively failed to reach statistical significance for 4 and 6.5 mm pupil diameters. In contrast, a significant reduction in MRSE (mean change 1.62 (SD 3.08D), p=0.013) was observed over the same period. Wavefront cylinder was significantly reduced in 4mm diameter pupils after CXL (mean change -0.48D, p=0.035) although manifest cylinder failed to reach significance. Both UCVAand BCVA were significantly improved following CXL. Mean preoperative UCVA was 20/114 and postoperatively was 20/93. Mean preoperative BCVA was 20/35 and postoperatively improved to 20/30 following CXL.
Conclusions: :
CXL appears to reduce higher order wavefront aberrations which may contribute to improvements seen in UCVA and BCVA following treatment. Although, manifest refraction shows improvements following CXL wavefront refractions remain relatively stable.
Clinical Trial: :
www.clinicaltrials.gov NCT00647699 & NCT00674661
Keywords: keratoconus • refractive surgery: complications • cornea: clinical science