Apparatus for use in the treatment of strabismic amblyopia in a subject having a non-amblyopic eye that performs better and an amblyopic eye that performs worse, the amblyopic eye having a central scotoma, the apparatus comprising image presentation means adapted to display a first image to the non-amblyopic eye and a second image to the amblyopic eye. The first and second images being presented to the subject so as to be perceived as coincidental wherein the first image and the second image include a common background, the apparatus further comprising eye tracking means adapted to monitor the direction of gaze of the non-amblyopic eye and the amblyopic eye on the first and second images respectively. The apparatus further comprising means for creating a region of degradation at the point of fixation of the first image, and for increasing the area of the region a degradation, wherein, in use of the apparatus, the non-amblyopic eye is fixed on the point of fixation prior to creation of the region of degradation and until the area of the region of degradation reaches a certain magnitude. Whereupon, the amblyopic eye takes up fixation, fixation of the amblyopic eye being indicated by a change in the direction of gaze of the amblyopic eye detected by the eye tracking means. The area of said region of degradation at which said take-up of fixation by the amblyopic eye occurs providing an indication of the size of the central scotoma of the amblyopic eye.
