A Novel Method of Measuring the Sagittal Depth of Scleral Contact Lenses Using Anterior Segment Optical Coherence Tomography

Scleral contact lenses (SCLs) are rigid gas-permeable contact lenses rest on the
sclera and vault the cornea. Because of this SCLs are able to mask surface irregularities
by creating a new refractive surface, which also makes sagittal depth arguably the most
important parameter used in the process of fitting SCLs. Regrettably, not all manufactures of SCLs make this parameter available for practitioners for reference,
necessitating an efficient and accurate method for the measurement this parameter. In
this study, a device was created to hold a scleral contact lens so it could be easily scanned by anterior segment optical coherence tomography (AS-OCT). A method was devised to ensure accurate measurements could be obtained and the SCL was imaged. Using digital calipers in the AS-OCT software, 3 measurements were obtained. The averages of 30 SCLs were then compared to the reported values from the contact lens manufacturer. Using basic statistical analysis, it was determined that the average difference between the reported sagittal depth and the measured sagittal depth was 7.33 J.lm with an average standard deviation of 18.08 J.lm and a 95% confidence interval of0.58 to 14.08 f.lm. The maximum difference between the reported sagittal depth and the measured sagittal depth was 53.33 J.lm and the min with a minimum difference of -23.33 J.lm. The data demonstrates the viability of AS-OCT in the measurement of SCLs.