RESUMEN
PURPOSE: One clinical approach to address poor front surface wettability during scleral lens wear is the use of a "reverse piggyback" system (a soft contact lens applied to the anterior surface of a scleral lens). The aim of this study was to compare the magnitude of corneal oedema induced following short-term reverse piggyback scleral lens wear and standard scleral lens wear. METHODS: Ten young (mean age 22 ± 6 years) healthy participants with normal corneas were recruited. On separate days, central corneal thickness and fluid reservoir thickness were measured using optical coherence tomography before and after 90 min of standard scleral lens wear (Kerectasia Alignment Tangent Torus diagnostic lenses, hexafocon A, Dk 100 × 10-11 (cm2 /s)(ml O2 /ml × mmHg), Capricornia Contact Lenses, capcl.com.au) and reverse piggyback scleral lens wear (the same scleral lens with a Dailies Total 1®, delefilcon A, Dk 140 × 10-11 (cm2 /s)(ml O2 /ml × mmHg), Alcon, alcon.com, applied to the anterior scleral lens surface). RESULTS: After correcting for small variations in the initial central fluid reservoir thickness, central corneal oedema was similar between the reverse piggyback (2.32 ± 1.15%) and standard scleral lens conditions (2.02 ± 0.76%; p = 0.45). CONCLUSIONS: Following 90 min of lens wear, the highly oxygen-permeable reverse piggyback system did not induce a clinically or statistically greater magnitude of central corneal oedema compared with standard scleral lens wear in young adults with healthy corneas. This approach may be suitable to address poor front surface scleral lens wettability or to correct residual refractive error during diagnostic scleral lens fitting.
