Low-cost, Smartphone-based Specular Imaging and Automated Analysis of the Corneal Endothelium

PurposeSpecular and confocal microscopes are important tools to monitor the health of the corneal endothelium (CE), but their high costs significantly limit accessibility in low-resource environments. In our study, we developed and validated a low-cost, fully automated method to quantitatively evaluate the CE using smartphone-based specular microscopy. MethodsA OnePlus 7 Pro smartphone attached to a Topcon SL-D701 slit-lamp was used to image normal the central corneal endothelium using the specular reflection technique. Images were automatically processed on-device and endothelial cell density (ECD), percentage of hexagonal cells (HEX), and coefficient of variation (CV) values were determined using our novel image analysis algorithm. The morphometric parameters generated from the images taken by Tomey EM-4000 specular microscope were compared between the testing modalities. ResultsNo significant differences in ECD (2799 {+/-} 156 cells/mm2 vs 2779 {+/-} 166 cells/mm2; p=0.28) and HEX (52 {+/-} 6% vs 53 {+/-} 6%; p=0.50) computed by smartphone-based specular imaging and specular microscope, respectively, were found. A statistically significant difference in CV (34 {+/-} 3% vs 30 {+/-} 3%; p<0.01) was found between the two methods. The concordance achieved between the smartphone-based method and the Tomey specular microscope is very similar to the concordance between two specular microscopes reported in the literature. ConclusionsSmartphone-based specular imaging and automated analysis is a low-cost method to quantitatively evaluate the CE with accuracy comparable to the clinical standard. Translational RelevanceThis tool can be used to screen the CE in low-resource regions and reveal the need for further investigation of suspected corneal endotheliopathies.