Qualitative and Quantitative Analysis of the Corneal Endothelium With Smartphone Specular Microscopy.

PURPOSE

We sought to demonstrate the feasibility of a lower-cost, portable method for qualitative and quantitative analysis of the corneal endothelium using a smartphone and slit-lamp biomicroscope.

METHODS

In this study, at a single academic center, we recruited healthy participants to undergo imaging of the corneal endothelium using both a smartphone-based method and a specular microscope. Participants first had their eyes imaged with a CellChek NSP-9900 Specular Microscope (Konan Medical, Inc, Irvine, CA). For image capture on the smartphone, a beam of light approximately 0.2 mm in diameter was directed to the center of the cornea with a slit-lamp biomicroscope to achieve specular reflection. With 40× zoom on the slit-lamp and 4K video mode set on an iPhone 7 Plus held to an ocular, the corneal endothelium was recorded until the hexagonal pattern of cells was identified and the sharpest frame from the video was selected.

RESULTS

The videos were analyzed from 14 sets of eyes (average length 2 minutes 40 seconds). The average intraclass correlation coefficient was 0.67 (95% confidence interval, 0.43-0.82). The mean difference between smartphone endothelial cell count and specular endothelial cell count was -209 cells/mm (SD = 483 cells/mm), which did not achieve significance (P = 0.14). A Bland-Altman analysis with simple linear regression showed no proportional bias when comparing the 2 modalities (coefficient = -0.20; t-value = -0.42; P = 0.68).

CONCLUSIONS

Smartphone specular microscopy is capable of qualitative and quantitative analysis of the corneal endothelium. Further refinement to standardize the light source and automate analysis will increase feasibility.