Qualitative Assessment of Scleral Shape Patterns Using A New Wide Field Ocular Surface Elevation Topographer: The Sssg Study
By Gregory DeNaeyer, OD, Donald R. Sanders, MD, PhD, Eef van der Worp, OD, Jason Jedlicka, OD, Langis Michaud, OD, Sheila Morrison, OD
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. This was a qualitative assessment of scleral shape patterns.
The Scleral Shape Study Group (SSSG) collaborated on this research. Data were 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 versus meridian at a 16-mm diameter from the corneal center was generated for each eye. Scleral shape patterns were reviewed in all cases and classified according to recurring characteristics.
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 high point to high point or low point to low point (Group 2). Fifty-seven cases (40.7%) had asymmetric high points (or elevations) or asymmetric low points (or depressions) 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).