Impact of Scleral Lens Front Surface Eccentricity on Visual Acuity, Contrast Sensitivity, and Higher-Order Aberrations in Eyes With Keratoconus

Purpose: To investigate the effect of front surface eccentricity (FSE) of scleral lenses (SLs) on corrected distance visual acuity (CDVA), contrast sensitivity (CS), and higher-order aberrations (HOAs) in keratoconic eyes.Methods: Fifteen keratoconic eyes fitted with BostonSight SCLERAL lenses of different eccentricity values (FSE0=0, FSE1=0.30, and FSE2=0.60). CDVA, CS, and HOAs were measured at baseline and after 30 min of SL wear. CDVA and CS were measured with the Early Treatment Diabetic Retinopathy Study and Pelli-Robson chart, respectively, and iTrace aberrometer was used to evaluate the HOAs.Results: Baseline CDVA was 0.30 +/- 0.29, which significantly improved to 0.10 +/- 0.11, 0.05 +/- 0.06, and 0.05 +/- 0.08 logMAR with FSE0, FSE1, and FSE2, respectively (P<0.05). The post hoc showed no significant difference between eccentricities. Baseline CS was 1.19 +/- 0.47, which improved to 1.54 +/- 0.12, 1.59 +/- 0.10, and 1.60 +/- 0.11 with FSE0, FSE1, and FSE2, respectively (P<0.01), but post hoc showed no significant difference between eccentricities. A statistically significant reduction was found in HOAs when compared with baseline (P<0.01). Comparison between eccentricities showed a significant difference only between FSE0 and FSE1 for RMS coma (P=0.01) and RMS spherical aberrations (P=0.004) where FSE1 showed better performance in reducing HOAs compared with FSE0. HO-RMS, RMS secondary astigmatism, and RMS trefoil showed no significant difference between eccentricities, but FSE1 and FSE2 performed superior to FSE0.Conclusion: BostonSight SCLERAL lenses with varying eccentricities corrected a significant amount of HOAs and improved CDVA and CS in keratoconus patients. Practitioners should be aware of this distinct feature of SLs and use it as needed to improve visual performance.