Comparison of Smartphone Photography, Single-Lens Reflex Photography, and Field-Grading for Trachoma
John M. Nesemann, Michael I. Seider, Blake M. Snyder, Robi N. Maamari, Daniel A. Fletcher, Berhan A. Haile, Zerihun Tadesse, Nicole Varnado, Sun Y. Cotter, E. Kelly Callahan, Paul M. Emerson, Todd P. Margolis, Thomas M. Lietman, Jeremy D. Keenan
Abstract
Conjunctival examination for trachomatous inflammation-follicular (TF) guides public health decisions for trachoma. Smartphone cameras may allow remote conjunctival grading, but previous studies have found low sensitivity. A random sample of 412 children aged 1-9 years received an in-person conjunctival examination and then had conjunctival photographs taken with 1) a single-lens reflex (SLR) camera and 2) a smartphone coupled to a 3D-printed magnifying attachment. Three masked graders assessed the conjunctival photographs for TF. Latent class analysis was used to determine the sensitivity and specificity of each grading method for TF. Single-lens reflex photo-grading was 95.0% sensitive and 93.6% specific, and smartphone photo-grading was 84.1% sensitive and 97.6% specific. The sensitivity of the smartphone-CellScope device was considerably higher than that of a previous study using the native smartphone camera, without attachment. Magnification of smartphone images with a simple attachment improved the grading sensitivity while maintaining high specificity in a region with hyperendemic trachoma.