Anomalous intraocular pressure changes in Chagas' disease elicited by postural test.

We compared the effects of postural changes on intraocular pressure, systemic blood pressure, and pupil size with and without induced mydriasis in 15 chronic chagasic patients and 20 healthy age-matched controls. The chagasic patients showed a marked fall in intraocular pressure on rising. However, systemic systolic blood pressure changes and pupil size in patients did not differ from those measured in controls. Our findings may be explained by an alteration in the autonomic ocular system that regulates homeostasis of ocular pressure and the probable existence of a baroreceptor arc-reflex that restores the equilibrium of sudden changes in the intraocular pressure.