A method for detecting strabismus in at least one image comprising a subject's eyes, wherein the at least one image has been obtained using an apparatus comprising a light source and a target offset from the light source, the method comprising, for each of the subject's left and right eyes: determining, from the image, a reflection offset distance, being the distance between a reference point of the eye and a reflection of a light source on the eye； determining a difference between the reflection offset distance and a reference reflection offset distance for the corresponding left or right eye, wherein the reference reflection offset distance has been determined based on relative positions of the light source, the target and the subject's head； and determining whether the difference is less than a difference threshold value for determining whether the subject has a strabismus.
