The corneoscleral shape in keratoconus patients with and without specialty lens wear

Abstract

Purpose: To evaluate differences in corneoscleral shape in keratoconus patients with and without specialty lenses compared to controls.

Methods: A cross-sectional study was performed comparing three groups of keratoconus eyes: 24 lens-naïve keratoconus eyes (17 patients; group 1), 7 eyes with corneal lens wear (7 patients; group 2) and 7 eyes with scleral lens wear (7 patients; group 3). For comparison, 25 eyes of 25 emmetropic participants and 11 eyes of 11 astigmatic participants were included. Corneoscleral topography measurements taken with the Eye Surface Profiler (ESP, Eaglet Eye BV, Houten, Netherlands) were exported and assessed using custom-made software to demarcate the limbal radius, and to calculate sagittal height and corneoscleral asymmetry.

Results: In non-lens wearing keratoconus patients, sagittal height was found to be significantly larger than in control eyes, in both the corneal periphery and sclera (paired t-test, pairwise comparisons p < 0.01). The level of peripheral corneal and scleral asymmetry was also significantly higher in non-lens wearing keratoconus eyes compared to controls (t-test, p < 0.01). Both corneal and scleral lens wear resulted in significant changes to the shape of the corneal periphery and sclera. In all 3 groups of keratoconus eyes, asymmetry of the peripheral cornea showed a very strong correlation with scleral asymmetry (R² = 0.90, 0.86 and 0.85 for groups 1-3, respectively).

Conclusion: The corneal periphery and sclera have a distinctly different shape in keratoconus eyes compared to controls. Specialty lens wear induces significant regional changes to the shape of the anterior eye in keratoconus eyes.

Keywords: Corneoscleral shape; Keratoconus; Scleral lens; Scleral topography; Specialty lenses.