A comparison of the short-term settling of three scleral lens designs

Scleral gas-permeable lenses are rapidly gaining international popularity. Unlike corneal gas-permeable lenses, scleral lenses are fitted to the bulbar conjunctiva and settle into the tissue after insertion. To date, we are unaware of any studies examining the settling behavior of three varying scleral lens designs. The purpose of this study was to quantify the mean total settling and mean rates of settling for three scleral lens designs: Onefit P&A (Blanchard Contact Lens, Inc), Mini Scleral Design (msd) (Blanchard Contact Lens, Inc), and Jupiter (Visionary Optics).

A randomized, repeated-measures study of Onefit P&A, msd, and Jupiter was performed. Subjects were fitted from a trial lens set, according to the manufacturer's guidelines. After insertion, lens settling was measured at 0 minutes, 15 minutes, 30 minutes, 45 minutes, 1 hour, 2 hours, 4 hours, 6 hours, and 8 hours. Statistical analyses were performed using analysis of variance and two-stage, nonlinear regression analyses of settling over time.

On average, the Onefit P&A, msd, and Jupiter lenses settled a total of 113.7, 133.7, and 88.1 μm, respectively. Although the rates of settling were not linear, analysis of variance revealed a significant difference in the average settling rates (p < 0.05) among the groups. Tukey analyses revealed a significant difference in the settling rates for msd and Jupiter comparison (p < 0.05). Nonlinear regression analyses predicted that the lenses settled to about 80% of the final estimated values for the Onefit P&A lens, 90% for msd, and 99% for the Jupiter, after 8 hours.

We concluded that the amount of settling varied significantly among the three lens designs. Settling rates were greatest shortly after insertion. Larger lenses were estimated to be settled by 8 hours. Based on the results of this short-term study, careful consideration to the settling patterns of individual scleral lens designs should be given.