Effects of a semi-scleral contact lens on refraction and higher order aberrations

Purpose: To investigate effects of Rose K2 XL semi-scleral contact lenses (Menicon Co.) on visual acuity and higher-order aberrations in eyes with irregular corneas. Methods: One hundred and twelve eyes of 84 patients fitted with Rose K2 XL lenses were analysed. Participants were in 4 clinical groups: keratoconus, intra-corneal ring segments, radial keratotomy, and penetrating keratoplasty. Corrected distance visual acuity and ocular aberrations were determined before lens wear and 60 min into lens wear. The i-Trace aberrometer was used to determine aberrations at 4.5 mm pupil size. Results: There were 55, 22, 19 and 16 eyes in keratoconus, intra-corneal ring segments, radial keratotomy and penetrating keratoplasty groups, respectively. Before lens wear, eyes had poor corrected distance vision acuity (mean and standard deviation +0.55 ± 0.33 logMAR), high negative spherical equivalent refraction (−6.4 ± 3.7 D), high cylindrical errors (4.5 ± 2.2 D), large higher-order root-mean-squared (HO-RMS) aberration (1.5 ± 1.3 μm) and large higher-order aberration components. Cylinder was particular high for the penetrating keratoplasty group (mean 5.9 ± 2.5 D), root-mean-squared third-order coma was lowest for the radial keratotomy group (0.7 ± 1.0 μm), and fourth-order spherical aberration was highly negative for the intra-corneal ring segment group (co-efficient –0.4 ± 0.7 μm). With lens wear, the values changed considerably. Corrected distance visual acuity improved by 0.51 ± 0.31 logMAR, cylinder decreased by 3.6 ± 2.1 D, HO-RMS aberration reduced by 1.1 ± 1.2 μm, and higher-order aberration components decreased considerably. Magnitudes of group changes reflected the magnitudes before lens wear. Conclusions: Rose K2 XL semi-scleral contact lenses were effective in improving vision and reducing ocular aberrations for eyes with irregular corneas.