Peripheral scleral lens modifications and tear exchange

To quantify the effect of landing zone modifications on tear exchange during short-term scleral lens wear.

Nine healthy adults with normal corneas wore scleral lenses with three different landing zone modifications (toric landing zone (control condition), peripheral notches, or channels) in a randomised order. Following the application of 10 µl of 2 % sodium fluorescein, Eye Surface Profiler (ESP) images were captured over a period of 100 min. Sodium fluorescein was reapplied at 90 min to assess tear exchange following lens settling. Central and peripheral fluorescent intensity data (quantified in arbitrary units, AU) were extracted from the ESP and analysed using customised software in MATLAB.

Fluorescent intensity varied significantly with lens design, time, and corneal location (p < 0.001). Averaged across all time points, the channel design displayed a higher level of fluorescent intensity (22 ± 2 AU) compared to the toric control (19 ± 1 AU) (p < 0.01) and notch designs (18 ± 1 AU) (p < 0.001). Following the reapplication of sodium fluorescein after 90 min of lens wear, the channel design also displayed a greater increase in fluorescent intensity ten minutes later (15 ± 3 AU increase) compared to the toric (10 ± 5 AU increase) and notch design (12 ± 5 AU increase) averaged across both central and peripheral locations (groove > toric and notch, both p < 0.05).

Landing zone modifications influence tear dynamics during short-term scleral lens wear. The channel design provided a consistent increase in tear ingress, mainly in the periphery. These findings provide quantitative evidence that channel modifications can enhance tear exchange in the short-term and may inform future innovations in scleral lens customisation.