Miniscleral lens wear influences corneal curvature and optics

Purpose: Transient changes in corneal topography associated with soft and conventional or reverse geometry rigid contact lens wear have been well documented; however, only a few studies have examined the influence of scleral contact lens wear upon the cornea. Therefore, in this study, we examined the influence of modern miniscleral contact lenses, which land entirely on the sclera and overlying tissues, upon anterior corneal curvature and optics. Methods: Anterior corneal topography and elevation data were acquired using Scheimpflug imaging (www.pentacam.com) immediately prior to and following 8 h of miniscleral contact lens wear in 15 young healthy adults (mean age 22 +/- 3 years, eight East Asian, seven Caucasian) with normal corneae. Corneal diurnal variations were accounted for using data collected on a dedicated measurement day without contact lens wear. Corneal clearance was quantified using an optical coherence tomographer (RS-3000, www.nidek.com) following lens insertion and after 8 h of lens wear. Results: Although corneal clearance was maintained throughout the 8-h lens wear period, significant corneal flattening (up to 0.08 +/- 0.04 mm) was observed, primarily in the superior mid-peripheral cornea, which resulted in a slight increase in against-the-rule corneal astigmatism (mean +0.02/-0.15 x 94 for an 8 mm diameter). Higher order aberration terms of horizontal coma, vertical coma and spherical aberration all underwent significant changes for an 8 mm corneal diameter (p <= 0.01), which typically resulted in a decrease in RMS error values (mean change in total higher order RMS -0.035 +/- 0.046 mu m for an 8 mm diameter). There was no association between the magnitude of change in central or mid-peripheral corneal clearance during lens wear and the observed changes in corneal curvature (p > 0.05). However, East Asian participants displayed a significantly greater reduction in corneal clearance (p = 0.04) and greater superior-nasal corneal flattening compared to Caucasians (p = 0.048). Conclusions: Miniscleral contact lenses that vault the cornea induce significant changes in anterior corneal surface topography and higher order aberrations following 8 h of lens wear. The region of greatest corneal flattening was observed in the superior-nasal mid-periphery, more so in East Asian participants. Practitioners should be aware that corneal measurements obtained following miniscleral lens removal may mask underlying corneal steepening.