Precise measurement of scleral radius using anterior eye profilometry

Purpose

To develop a new and precise methodology to measure the scleral radius based on anterior eye surface.

Methods

Eye Surface Profiler (ESP, Eaglet-Eye, Netherlands) was used to acquire the anterior eye surface of 23 emmetropic subjects aged 28.1 ± 6.6 years (mean ± standard deviation) ranging from 20 to 45. Scleral radius was obtained based on the approximation of the topographical scleral data to a sphere using least squares fitting and considering the axial length as a reference point. To better understand the role of scleral radius in ocular biometry, measurements of corneal radius, central corneal thickness, anterior chamber depth and white-to-white corneal diameter were acquired with IOLMaster 700 (Carl Zeiss Meditec AG, Jena, Germany).

Results

The estimated scleral radius (11.2 ± 0.3 mm) was shown to be highly precise with a coefficient of variation of 0.4%. A statistically significant correlation between axial length and scleral radius (R² = 0.957, p < 0.001) was observed. Moreover, corneal radius (R² = 0.420, p < 0.001), anterior chamber depth (R² = 0.141, p = 0.039) and white-to-white corneal diameter (R² = 0.146, p = 0.036) have also shown statistically significant correlations with the scleral radius. Lastly, no correlation was observed comparing scleral radius to the central corneal thickness (R² = 0.047, p = 0.161).

Conclusions

Three-dimensional topography of anterior eye acquired with Eye Surface Profiler together with a given estimate of the axial length, can be used to calculate the scleral radius with high precision.