Scleral Fluid Reservoir Thickness Decreases Most Rapidly Within Two Hours

The advancement of technology—specifically OCT—has allowed an exponentially greater understanding of the eye and has provided countless research findings that can be clinically relevant for practitioners. With scleral lenses, both thickness and symmetry in the post-lens fluid reservoir can influence optical quality and corneal physiology, making reservoir dynamics an important aspect in providing best quality care for patients.However, most prior research has only examined the central or mid-peripheral corneal measurements because of imaging limitations like instrument scan size or data availability, due to obfuscation from the upper eyelid. In a recent study published in Eye and Vision, the use of wide-angle imaging with eyelid retraction allowed simultaneous photos of the central and peripheral cornea. Changes in fluid reservoir thickness are influenced by factors of lens design, initial reservoir thickness and lens diameter. These SS-OCT scans from the study were taken with an image width of 16mm using the anterior segment 3D radial scan mode. Each OCT image was analyzed to detect the anterior and posterior boundaries of the fluid reservoir. The fluid reservoir was analyzed across central, mid-peripheral and peripheral regions. Photo: Wang F, et al. Eye Vis (Lond). July 14, 2025. Click image to enlarge. Using customized software, researchers from Australia and China were able to automatically segment the post-lens fluid reservoir images across a 12mm diameter with 75 participants—29 myopes with regular corneas and 46 irregular corneas, which included 35 keratoconic eyes and 11 post-keratoplasty. All participants were fit with customized sclerals and images were taken at 0, 30, 60, 120 and 240 minutes after lens application.It was observed that fluid reservoir thickness decreased over time exponentially, with most rapid reduction in the first two hours of wear; no differences were seen over time between the three subsets of eyes. Fluid thickness reduction varied slightly over four hours between the three regions, being 149µm in the central region, 139µm in the mid-peripheral region and 131µm in the peripheral one. For myopic and post-keratoplasty patients, the fluid reservoir was thinnest in the superior mid-periphery, while for keratoconic patients, it was thinnest centrally. In all groups, the reservoir was thickest inferiorly, with the most amount of asymmetry seen along the vertical meridian.The authors offer a greater level of detail for their findings in the discussion section of the paper. After one hour of lens wear, they explain, fluid thickness reduced by 19% to 26%. Over four hours, small differences in fluid reservoir thickness changes were seen between the groups, with ~40% reduction from baseline centrally, ~38% midperipherally and ~35% peripherally.It was found that the fluid reservoir was thinnest in different areas for myopic and post-keratoplasty vs. keratoconic patients (superior mid-peripheral vs. central). The researchers elaborate that this difference was most likely due to corneal morphology variance between the groups, with added influence of inferior scleral lens decentration or tilt.From these findings, the investigators suggest that, “in clinical practice, when assessing fluid reservoir thickness, scleral lens practitioners must pay attention not only to central cornea, but also consider the vertical asymmetry of fluid reservoir.”Click here for the journal source. Wang F, Vincent SJ, Cho P, et al. Wide-angle fluid reservoir thickness changes during short-term scleral lens wear. Eye Vis (Lond). July 14, 2025. [Epub ahead of print].