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WIDE FIELD OCULAR SURFACE ELEVATION TOPOGRAPHER, The SSSG Study, SCLERAL SHAPE PATTERNS
Background and Objectives: Objective was to examine new findings regarding conjunctival/scleral shape mapped with a novel wide field elevation topography device and software, to propose a new classification system for scleral shape.
Methods: The Scleral Shape Study Group (SSSG) collaborated on this research. Data was collected from 152 eyes of prospective scleral lens patients utilizing a new topography device and software specifically designed to measure and map the sclera out to as much as 22 mm. Circumferential scleral plots of sagittal height vs. meridian at 14, 15 and 16mm diameters from the corneal center were generated for each eye. Scleral shape patterns were reviewed in all cases and classified according to recurring characteristics.
Results: Twelve eyes were excluded from the analysis due to incomplete data. Of the remaining 140 eyes, 8 (5.7%), of the plots were primarily spherical (Group 1) and 40 (28.6%) were primarily regularly toric, largely conforming to a toric (Sin2) curve with approximately 180° periodicity or interval between elevation to elevation or depression to depression (Group 2). Fifty-seven cases (40.7%) had asymmetric depressions (or steep areas) or asymmetric elevations (or flat areas) which were classified as Group 3. The remaining 35 cases (26%) had a recognizable toric pattern with elevations and depressions but they were irregularly spaced or did not have the customary 180° periodicity (Group 4).
Conclusion: A new classification of conjunctival/scleral shape is presented based upon data now available through wide field elevation topography, which could be helpful in scleral lens fitting and potentially soft lens fitting as the landing zone of these lenses are beyond the corneal borders.
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