The effect of scleral lenses on vision, refraction and aberrations in post‐LASIK ectasia, keratoconus and pellucid marginal degeneration

Purpose: To quantify the effect of a single scleral lens design on visual acuity and ocular higher-order aberrations in eyes with post–LASIK ectasia, keratoconus and pellucid marginal degeneration (PMD) that could not achieve satisfactory vision with spectacles or soft contact lenses. Methods: Forty-six eyes of 28 participants fitted with diagnostic scleral lenses (KeraCare) were analysed, including 19, 15 and 12 eyes with post-LASIK ectasia, keratoconus and PMD, respectively. Corrected distance visual acuity (CDVA) and ocular aberrations were measured prior to lens wear and during lens wear after 60 min of settling. An i–Trace aberrometer was used to determine aberrations over a 4.5 mm diameter pupil. Results: Before lens wear, the median (95% confidence interval) values across all groups were: CDVA 0.30 (0.30, 0.40) logMAR, spherical equivalent refraction –2.75 (–5.25, –2.12) D, cylindrical refraction 3.75 (2.50, 5.00) D, higher–order–root–mean–square error (HO-RMS) 0.90 (0.64, 1.03) μm and vertical coma co-efficient C(3,–1) –0.32 (–0.42, –0.12) μm. RMS coma of 0.52 (0.40, 0.74) μm was higher for the keratoconus group than for the other groups (p < 0.05). During lens wear, values improved considerably across all groups: CDVA 0.0 (0.0, 0.00) logMAR, spherical equivalent refraction –0.50 (–0.75, +0.50) D, cylindrical refraction 0.50 (0.00, 0.50) D, HO-RMS 0.32 (0.26, 0.42) μm and C(3,–1) +0.12 (+0.02, +0.19) μm (all p < 0.001 compared to pre-lens wear). While reduced significantly, RMS coma remained higher in the keratoconus group at 0.35 (0.31, 0.52) μm than in the post–LASIK ectasia and PMD groups at 0.17 (0.12, 0.21) μm and 0.07 (0.02, 0.46) μm, respectively (p < 0.05). Conclusions: The KeraCare scleral contact lens reduced ocular aberrations and improved visual acuity in patients with post–LASIK ectasia, keratoconus and PMD. The sign of vertical coma changed in keratoconus and PMD.