Development of a cone‐mediated dark adaptation test on a smartphone

Abstract

Aims/Purpose: Dark adaptometry is considered a useful tool for investigating retinal neurodegenerative diseases. While it has been demonstrated that the loss of rod photoreceptors occurs before the loss of cones, foveal cones are also impacted during the initial stages of age‐related macular degeneration. Our aim was to develop a test to assess cone‐mediated dark adaptation (DA) based on the MOBILE‐DA smartphone app.Methods: The MOBILE‐DA smartphone app for testing rod‐mediated DA was modified to assess cone‐mediated DA. Using an Android smartphone, and a 3° diameter achromatic flashing stimulus centered on the fovea, the measurements were made using an adaptive staircase of 0.007 cd/m2 level up – 0.009 cd/m2 level down. In a dark room, the smartphone was placed 40 cm from the subject, and the luminance thresholds were measured monocularly for 5 min following almost complete photopigment bleaching using a long‐duration light exposure (60 seconds). Luminance Threshold (LT) recovery functions were fitted to an exponential decay model to determine the time constant (τ, seconds) of cone sensitivity recovery and final cone LT.Results: The cone‐mediated DA measured by the smartphone app resulted in τ of 91 ± 15 seconds; final cone LT of −2.29 ± 0.10 log cd/m2, and R2 of 0.96 ± 0.02. The time constant and final threshold values obtained through this app were comparable to those obtained through other established techniques.Conclusions: The smartphone app for evaluating cone‐mediated dark adaptation proved effective in tracking the rapid changes in luminance threshold that take place during this process. These findings suggest that the MOBILE‐DA app is well‐suited for measuring cone‐mediated dark adaptation.