Comparison of Five Camera Systems for Capturing and Grading Trachoma Images

As training of trachoma graders using live participants grows increasingly difficult and expensive, alternative ways are needed possibly through replacement of field grading with photography. However, minimum specifications for a camera system capable of capturing high quality images have not been defined. This study compared images captured using four smartphones with those from a Nikon SLR camera for image quality and assessment of trachomatous inflammation - follicular (TF).

The smartphones - Samsung Galaxy S8 (S8), Techno Camon 17 pro (TC), Infinix Note 10 pro (IN), Huawei p30 pro (HP) - were chosen for their availability and likelihood of good performance based on specifications without external attachments. All smartphones were used in random order for each participant.

129 children in Kongwa, Tanzania were enrolled (32.8% TF prevalence). The SLR camera had the least percent of ungradable images (3.1%), followed by the S8 (14%), HP (23.4%), IN (65.9%), and TC (71.2%). The S8 and the HP were significantly more likely to take ungradable images if they were used toward the end of the camera rotation. Agreement between the SLR and field grade was kappa = 0.73. Agreement between the field grade and gradable images from the S8 (0.68) and HP (0.8) was measured.

Published specifications did not predict the success of using different smartphones for everted eyelid photographs; proprietary post-processing software likely influenced gradeability. Smartphones, though we cannot recommend those tested in this study, may be viable for capturing images for trachoma provided the quality of images from the field are adequate.