Variation of clearance considering viscosity of the solution used in the reservoir and following scleral lens wear over time

Abstract Purpose This study aims to evaluate the settling of a scleral lens and if this process is influenced by the nature of the fluid layer. Methods A prospective, non-randomized control study was performed using an 18 mm scleral lens. They were fitted with a central clearance of 400 um at insertion. One eye was randomly assigned to be fitted with a non-preserved gel solution of carboxymethylcellulose, while the other was inserted with non-preserved saline. Measurements of clearance in 3 locations were taken (OCT) at baseline, every 30 min up to 1h30 post insertion and every 2 h thereafter up to 6h00 of wear. A two-way repeated measure analysis of variance (liquids × times) was used to test central, nasal and temporal fluid thickness. Results Following 6 h of wear, the 18 mm lens had a mean central settling of 70.0 ± 9.8 μm, 36.7 ± 9.8 μm of which occurred within the first 30 min of wear. There was no significant difference between lenses filled with non-preserved saline to those with non-preserved gel. However, a paired comparison concluded to a significant difference between mean nasal settling (41.4 μm) and temporal settling (20.4 μm). Conclusion With respect to the lens studied, current results suggest that practitioners can evaluate the lens 30 min post insertion and can estimate the amount of fluid that will remain after lens stabilization by doubling the value obtained initially. The use of non-preserved saline or non-preserved more viscous solution to fill the lens does not influence its settling.