The effect of extended periods of mini-scleral lens wear on the conjunctival/episcleral and scleral thickness

Abstract

Purpose: To evaluate the conjunctival/episcleral thickness (CET) and anterior scleral thickness (AST) in patients with keratoconus with an extended duration of mini-scleral contact lens wear by utilizing anterior segment optical coherence tomography (ASOCT).

Methods: This study included 17 eyes of 17 patients with keratoconus with mini-scleral contact lens wear (Group 1), 20 eyes of 20 patients with keratoconus without any contact lens wear (Group 2), and 20 eyes of 20 healthy controls (Group 3). CET and AST were measured using AS-OCT (Triton, Topcon, Japan) at 1, 2, and 3 mm posterior to the scleral spur in the nasal, temporal, superior, and inferior quadrants.

Results: The median age of the mini-scleral contact lens group was 26, and the number of male patients was 14 (82.4 %). The superior CET values at 1 mm, 2 mm, and 3 mm statistically differed between the groups, with Group 1 having significantly lower values than Group 3 and Group 2 having statistically similar values to the remaining two groups. The inferior CET at 2 mm was lower in Groups 1 and 2 than in Group 3. The inferior CET at 3 mm was lower in Group 1 compared to Groups 2 and 3. AST was similar between the groups at all measured quadrants and distances. The duration of lens wear had a strong, statistically significant, negative correlation with the superior CET at 2 mm (rho: -0.847, p < 0.001) and a moderate, statistically significant, negative correlation with the superior CET at 3 mm (rho: -0.506, p < 0.038).

Conclusions: In this study, it was found that mini-scleral contact lens usage causes thinning in the conjunctival-episcleral layer, especially in the superior and inferior quadrants, but does not affect scleral thickness. AS-OCT is a non-invasive and clinically applicable technique for assessing the impact of contact lens use on the conjunctiva/episclera and sclera.

Keywords: Anterior scleral thickness; Conjunctival/episcleral thickness; Keratoconus; Mini-scleral contact lens.