Heterochromia pardus: implications of the spotted pale iris

Abstract

A pale iris is a well-recognized feature of congenital Horner's syndrome. We studied a 42-year-old man who had right ptosis, miosis and a paler iris since early childhood. Not only was there diffuse hypochromic, but 25 /ij'/>erchromic pigmented spots were superimposed on the affected iris. Pharmacological testing confirmed that the iris was denervated by a postganglionic noradrenergic lesion but that some sympathetic input to the iris was still present. Clinical and radiographic studies showed an absent right internal carotid artery.

Mechanisms are reviewed by which the sympathetic nervous system influences pigmentation. Perinatal damage to neurons of the superior cervical ganglion with subsequent partial reinnervation may account for some features of our patient's distinctive spots. A term 'heterochromia pardus' appears to characterize both the spotting and the pallor of the iris.