20 dioptre prism
(product code: 20DP)

• Used in the "20 base out prism test".
• One of the easiest, fastest and most effective ways of screening for binocular vision in young children.
• If the child is not cooperative enough to conduct other tests, a 20 dioptre base-out prism is put in front of one eye while shining a penlight (or even using a captivating fixation target). If the eyes adjust to the prism and the corneal reflexes become straight, fusion is present which proves the existence of binocular vision.
• Extremely useful for any optometrist / ophthalmologist / orthoptist.

£35