Retinal vasodilatation in the affected eye but reduced pressure autoregulation of both eyes in unilateral Coats’ disease

Abstract

Background Coats’ disease is characterized by vascular hyperpermeability, oedema and accumulation of exudates related to impairment of retinal vascular function. The background for the development of the disease is unknown, but it is likely that the study of diameter changes of retinal vessels may contribute to understanding the pathophysiology of the disease. Methods In seven patients with unilateral Coats’ disease (mean age = 34.7 years, range: 11–69 years), the baseline diameter and reactivity of retinal vessels during an increase in the arterial blood pressure by isometric exercise and in the metabolism by flicker stimulation were measured on video recordings of the retina obtained with the Dynamic Vessel Analyzer. Results The baseline diameter of retinal vessels was larger in the affected than in the unaffected eyes which was significant for the arterioles (p = 0.02), but not for the venules (p = 0.15). During an increase in the arterial blood pressure induced by isometric exercise, the normal contraction of arterioles was absent in both eyes (p > 0.7), whereas there was a significant dilatation of the venules in the unaffected eyes (p = 0.04). Stimulation with flickering light induced normal dilatation of retinal vessels in both affected and unaffected eyes. Conclusion Unilateral Coats’ disease is accompanied by vasodilatation in the affected eye but impaired pressure autoregulation in both eyes. A further investigation of the disease should include an elucidation of the background for dilatation of retinal vessels in affected eyes and whether impaired pressure autoregulation can be found in vessels elsewhere in the body.