Mini scleral contact lenses: settling period and its effect on peripheral refraction.

Abstract

Purpose : To compare the settling period or change in central corneal clearance (CCC; μm) of two different diameter mini scleral contact lens (MScCL) designs with spherical and toric peripheral curves and to determine the effect of CCC on peripheral refraction (PR; D).

Methods : Two MScCL designs (Katt, lens diameter 16.5 mm and Epicon, lens diameter 13.5 mm; Capricornia Contact Lens, Australia) with spherical and toric peripheral curves were fitted on 16 young adults (Katt, n=16; Epicon, n=10). Each of the 4 lenses was fitted on one eye only across four separate days. Subjects wore each lens for 8 hours and CCC (Tomey CASIA OCT; Japan), and PR (Shin-Nippon NVision-K 5001 autorefractor; Japan) at 10° steps along horizontal (± 35°) and vertical meridians (± 30°) were obtained after 10 minutes, 1, 2, 4 and 8 hours of lens wear.

Results : The greatest change in CCC occurred during the first 4 hours of lens wear for Katt lenses (sphere, 149 ± 42 μm; toric, 134 ± 41 μm; p<0.001) with no significant change in CCC measured between 4-8 hours of lens wear (sphere, 12 ± 18 μm; toric, 12 ± 15 μm; p>0.05).The greatest change in CCC measured with Epicon lenses was after 1 hour of lens wear (sphere, 54 ± 33 μm; toric, 84 ± 42 μm; p<0.0001) and no significant change in CCC was measured between 1-8 hours of lens wear (sphere, 38 ± 24 μm; toric, 39 ± 28 μm; p>0.05). No significant difference in change in CCC was found between spherical and toric peripheral curves for either lens design (Katt, p=0.28; Epicon, p=0.33). The spherical equivalent (M) and J₄₅ did not change significantly over time with any lens along the horizontal and vertical meridians (all p>0.05). With Epicon lens wear, J₁₈₀ values at all positions along the vertical meridian became more positive compared to baseline. In contrast, no significant change in J₁₈₀ was measured with Katt lenses.

Conclusions : The greatest change in CCC occurred within 4 hours for Katt lenses and 1 hour for Epicon lenses. This suggests lens diameter influences MScCL settling period. MScCLs with different peripheral curves do not seem to affect lens settling. Relative PR profiles did not change over time with Katt MScCLs. However, changes in the astigmatic component measured with Epicon lenses are currently unexplained and need further investigation.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.