Scleral topography analysed by optical coherence tomography

Purpose: A detailed evaluation of the corneo-scleral-profile (CSP) is of particular relevance in soft and scleral lenses fitting. The aim of this study was to use optical coherence tomography (OCT) to analyse the profile of the limbal sclera and to evaluate the relationship between central corneal radii, corneal eccentricity and scleral radii. Methods: Using OCT (Optos OCT/SLO; Dunfermline, Scotland, UK) the limbal scleral radii (SR) of 30 subjects (11 M, 19F; mean age 23.8 +/- 2.0SD years) were measured in eight meridians 45 degrees apart. Central corneal radii (CR) and corneal eccentricity (CE) were evaluated using the Oculus Keratograph 4 (Oculus, Wetzlar, Germany). Differences between SR in the meridians and the associations between SR and corneal topography were assessed. Results: Median SR measured along 45 degrees (58.0; interquartile range, 46.8-84.8 mm) was significantly (p < 0.001) flatter than along 0 degrees (30.7; 24.5-44.3 mm), 135 degrees (28.4; 24.9-30.9 mm), 180 degrees (23.40; 21.3-25.4 mm), 225 degrees (25.8; 22.4-32.4 mm), 270 degrees (28.8; 25.3-33.1 mm), 315 degrees (30.0; 25.0-36.9 mm), and 90 degrees (37.1; 29.1-43.4 mm). In addition, the nasal SR along 0 degrees were significant flatter than the temporal SR along 180 degrees (p < 0.001). Central corneal radius in the flat meridian (7.83 +/- 0.26 mm) and in the steep meridian (7.65 +/- 0.26 mm) did not correlate with SR (p = 0.186 to 0.998). There was no statistically significant correlation between corneal eccentricity and scleral radii in each meridian (p = 0.422). Conclusions: With the OCT device used in this study it was possible to measure scleral radii in eight different meridians. Scleral radii are independent of corneal topography and may provide additional data useful in fitting soft and scleral contact lenses.