Wide-angle fluid reservoir thickness changes during short-term scleral lens wear

To analyze the fluid reservoir thickness over the whole cornea during scleral lens settling using wide-angle optical coherence tomography (OCT) images and customized computer software.

A total of 75 participants were recruited - 29 (myopes) with regular corneas and 46 with irregular corneas (35 with keratoconus, and 11 post-keratoplasty). All participants were fitted with customized scleral lenses and anterior segment OCT (Tomey Casia 2) images were taken 0, 30, 60, 120, and 240 min after lens application at the dispensing visit. Customized software was used to automatically segment the anterior cornea and the posterior surface of the scleral lens and determine the fluid reservoir thickness at 17 corneal regions across a 12 mm diameter.

Fluid reservoir thickness decreased over time (P < 0.001) following an exponential decay, with no differences observed over time between the three groups (P = 0.97). The reduction in fluid reservoir thickness over four hours varied slightly between the central (149 ± 9 μm), mid-peripheral (139 ± 11 μm), and peripheral regions (131 ± 15 μm), P = 0.046. The fluid reservoir was thinnest in the superior mid-periphery for both the myopia and post-keratoplasty groups, and centrally for the keratoconus group. The fluid reservoir was thickest inferiorly for all groups, with the greatest level of asymmetry observed along the vertical meridian.

Fluid reservoir thickness decreased most rapidly during the first two hours of lens wear and followed an exponential decay for both regular and irregular corneas across all corneal locations. Fluid reservoir asymmetry was greatest along the vertical meridian with a thicker reservoir observed in the inferior corneal regions.