The overall aim of this study was to develop an algorithm to acquire, validate and analyse digital photos to detect manifest strabismus and inform whether referral is required. The authors describe a method to measure the difference in location of the corneal reflections as an indicator for manifest strabismus and its accuracy. Digital photos were taken in primary and off-centre fixation. Thirty-four image sets were analysed – 29 manifest and five latent strabismus. For latent strabismus, the mean corneal reflection location difference between eyes was -0.10±0.14mm in primary gaze and -2.02±0.39 in off-centre fixation. Thresholds of up to 0.5mm for primary and 2mm for off-centre were allowed. Based on these thresholds, sensitivity increased from 65.6% in primary to 79.3% in off-centre fixation. The authors conclude this method has promise and warrants further research.