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.