Method for detecting strabismus in images of the eyes

A method for detecting strabismus in at least one image comprising a subject's eyes, wherein the image has been obtained using an apparatus comprising a light source 102 and a target 104 offset from the light source, the method comprising, for each of the subject's eyes: determining from the image a reflection offset distance, being the distance between a reference point of the eye 302 and a reflection of the light source on the eye 220 (see figure 3); determining a difference between the reflection offset distance and a reference reflection offset distance, 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. The reference point of the eye 302 may be the pupil centre. The target may have a device to get the user's attention.