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Stephen J Vincent, David Alonso-Caneiro, Michael J Collins; Tissue compression following short-term miniscerlal contact lens wear. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):6078.
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© ARVO (1962-2015); The Authors (2016-present)
To quantify the regional (nasal, superior, temporal and inferior quadrants) and location specific (limbus to sclera) effects of short-term miniscleral contact lens wear on the morphometry of anterior ocular structures adjacent to the scleral lens landing zone.
Optical coherence tomography (OCT) images were captured before, immediately following and 3 hours after a short period (3 hours) of miniscleral contact lens wear for 10 young (mean 27±5 years), healthy participants. To allow comparison of subsequent scans, OCT images from each measurement session, for each participant, were aligned using custom written software by identifying common anatomical landmarks in each scanning laser ophthalmoscope en-face image (e.g. blood vessel bifurcations). To compensate for any natural diurnal variations, OCT measurements were repeated on a separate control day without contact lens wear following the same experimental protocol.
Following three hours of lens wear, statistically significant conjunctival/scleral thinning was observed, with a mean decrease in thickness of -24.16±3.6 μm (p<0.001), which diminished, but did not return to baseline three hours after lens removal (-16.97±1.9 μm, p<0.001). Tissue compression was observed across all quadrants, with the greatest thinning observed superiorly (-49.99 ± 8.52 µm, p<0.01). Averaged across all quadrants, the most thinning was observed 2 mm posterior to the scleral spur (-48.22 ± 5.79 µm), the approximate edge of the miniscleral landing zone. The global mean tissue compression immediately following lens removal was not associated with baseline scleral thickness (r=0.20, p=0.5) or apical corneal lens clearance (r=0.43, p=0.21).
Optimal fitting miniscleral contact lenses cause significant tissue compression in young healthy eyes, with the greatest thinning observed superiorly, most likely due to the additional force of the superior eyelid. These results partly explain the clinical observations of reducing apical corneal clearance and lens “settling” over the first few hours of miniscleral lens wear.
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