The Hirscheberg Test — A Re‐evaluation

The Hirschberg Test is one of the most widely used clinical methods for determining the relative rotational position of the eyes. Although Hirschberg determined the rotational position of the eye by relating the corneal reflex to iris topography, over the years a simple ratio of 1 mm = 7° has come into common use. A theoretical and experimental evaluation of the procedure indicates that although the mathematical description of the Hirschberg Test is net linear but is actually a sine function, for practical clinical purposes a simple ratio can be used to give an approximate measurement of ocular deviations of any amount. The best ratio for the average eye, however, is 1 mm = 22Δ