Vascular findings in primarily affected and fellow eyes of middle-aged patients with Coats' disease using multimodal imaging.

AIMS To investigate the retinal vascular structure and capillary anomalies of affected and fellow eyes of patients with unilateral Coats' disease using multimodal imaging. METHODS Clinical investigation of both eyes of each patient with diagnosed Coats' disease using ultra-widefield (UWF) fundus imaging, including UWF fluorescein angiography (UWFFA), spectral domain optical coherence tomography (OCT) and optical coherence tomography angiography (OCT-A). RESULTS We analysed 38 eyes of 19 patients with unilateral Coats' disease and found that all fellow eyes (19/19; 100%) revealed vascular alterations, detected by UWFFA, predominantly located in the temporal periphery. Thereby, 89% of the fellow eyes (17/19) presented capillary bed abnormalities, that did not exceed the capillary level; 58% (11/19) presented tortuous abnormalities and 26% (5/19) presented microaneurysmatic abnormalities, exceeding the capillary level. If primarily affected eyes presented central Coats' specific vascular abnormalities, fellow eyes revealed tortuous vascular abnormalities twice as often (78% (7/9) vs 40% (4/10); P=0.096). In primarily affected eyes, a tendency towards larger foveal avascular zones was revealed, compared to fellow eyes (0.28±0.16 mm2 vs 0.20±0.10 mm2; P=0.123). CONCLUSION The use of modern multimodal imaging allows the detection of even subtle vascular changes in fellow eyes of patients with Coats' disease. Coats' disease appears to be a bilateral ocular disease with a predominant manifestation in one eye of the affected patients.