The temporal dynamics of miniscleral contact lenses: Central corneal clearance and centration

Purpose To examine the time course of the reduction in central corneal clearance and horizontal and vertical lens translation (decentration) during miniscleral contact lens wear and the theoretical influence upon the optics of the post-lens tear layer. Methods Repeated high-resolution OCT images were captured over an 8 hour period of miniscleral contact lens wear (using a rotationally symmetric 16.5 mm diameter lens) in 15 young, healthy participants with normal corneae. Central corneal clearance and lens decentration were derived from OCT images using semi-automated image processing techniques. Results Central corneal clearance decreased exponentially over time, reducing by 76 ± 8 µm over 8 hours. Fifty percent of this reduction occurred within 45 minutes of lens wear and seventy-five percent within 2 hours, with thinning of the post-lens tear layer plateauing 4 hours after lens insertion. Lens translation exhibited a similar pattern of change (0.18 ± 0.04 mm temporal and 0.20 ± 0.09 mm inferior decentration) stabilising 1.5 - 2 hours after insertion. The change in the lens fit over time resulted in a small reduction in the power of the post-lens tear layer (-0.12 ± 0.01 D) and induced a prismatic effect of 0.01 ± 0.16 Δ base out and 0.50 ± 0.19 Δ base down relative to the pupil centre. Conclusions For the miniscleral contact lens studied, horizontal and vertical lens decentration followed an exponential decay over 8 hours that plateaued approximately 2 hours after lens insertion, while central post-lens tear layer thinning plateaued after 4 hours of lens wear