[Photo- and videographic determination of the dilatation deficit in differential diagnosis of Horner syndrome].

: Physiological anisocoria, a very frequent condition among normal subjects, must be differentiated from Horner's syndrome. Aside from a history including evaluation of older photographs, pharmacological pupil testing with cocaine eye drops has been the "gold standard". Measurement of dilation lag, occurring in Horner's syndrome, is much less common and normal values are missing. Therefore, we evaluated various photographic parameters for testing for the best parameter to discriminate Horner's syndrome (22 patients) from physiological anisocoria (16 patients). Additionally, we tested whether a commercially available camcorder is sufficient to record pupillary dilatation lag. An anisocoria of 0.6 mm or more 4s after switching off the illumination discriminates physiological anisocoria from Horner's syndrome with a sensitivity of 82% and a specificity of 69%. A dilatation speed of 1.1 mm/4 s shows the same ability to differentiate in anisocoria and does not provide any better results. Because of the good correlation between post-cocaine anisocoria and anisocoria after 4 s in darkness, photographic or videographic measurements of the pupillary dilatation lag may complete or in some cases even replace cocaine testing.