Scleral lens peripheral modifications and regional variations in corneal oedema

PURPOSE: To investigate the effect of peripheral scleral lens landing zone modifications upon short-term regional variations in corneal oedema. METHODS: Nine healthy participants wore different scleral lens designs ((1) spherical landing zone, (2) toric landing zone, (3) peripheral notches, and (4) peripheral channels) in a randomised order on four separate days for 100 min. Stromal oedema was quantified using high-resolution optical coherence tomography across the central, mid-peripheral, and peripheral cornea with the lens in situ. Eye Surface Profiler (ESP) images were also captured following the application of 10 μL of 2% sodium fluorescein, over a period of 100 min. Central and peripheral fluorescent intensity data were extracted from the ESP images and analysed using customised software to quantify tear exchange. RESULTS: The channel lens design displayed less central oedema compared to the toric design (1.57 ± 0.45% less oedema, p = 0.04). In the corneal periphery, the magnitude of oedema was less for both the toric lens (2.66 ± 0.66% less oedema, p = 0.02) and the channel design (3.39 ± 0.97% less oedema, p = 0.04) in comparison to the spherical lens design. A highly significant correlation was observed between the magnitude of peripheral tear exchange after 90 min of lens wear and the magnitude of peripheral oedema (r = -0.61, p < 0.001). CONCLUSIONS: Scleral lenses with either a toric landing zone or peripheral channels exhibited less peripheral corneal oedema than a spherical landing zone design, due to enhanced peripheral tear exchange.