Which ocular finding is more commonly associated with congenital Horner's syndrome compared to acquired Horner's syndrome?

Iris heterochromia is indeed a key ocular finding associated with congenital Horner's syndrome. This condition arises due to an interruption in the sympathetic pathway that innervates the eye and surrounding structures. In cases of congenital Horner's syndrome, patients may exhibit a distinct difference in iris color between the affected eye and the other eye. This occurs because, during the early stages of development, the sympathetic innervation to the melanocytes in the iris is compromised, resulting in a lack of pigmentation in the affected eye.

In contrast, acquired Horner's syndrome typically does not present with iris heterochromia. While it does feature other characteristic signs such as ptosis, miosis, and anhidrosis, these signs arise from different underlying causes that do not affect the developmental aspects of iris pigmentation. In acquired cases, the sympathetic pathways may become disrupted due to various external factors or conditions, but the iris pigmentation has already been established.

This distinction highlights the unique features of congenital vs. acquired Horner's syndrome, with iris heterochromia standing out as a significant clinical marker indicative of congenital origin. Understanding these differences is crucial for accurate diagnosis and management of patients presenting with Horner's syndrome.