Case of the Month | August 2021

This patient has proliferative diabetic retinopathy and likely also has Coats’ disease as an unrelated condition. The extensive hard exudates in the superonasal retina of the left eye are not acutely interfering with vision. The fundus photo shows dilation and telangiectasia of vascular network. This patient’s fluorescein angiogram did not come out well and was not helpful diagnostically.

There are other causes of hard exudate formation that should be considered. Diabetic retinopathy typically has less hard exudate formation, and it would be very atypical to see severe hard exudates concentrated outside the macula. Retinal capillary hemangiomas can induce extensive hard exudates, but they tend to track to the posterior pole. Retinal artery macroaneurysms can also manifest extensive hard exudates, but the hard exudates tend to encircle the macroaneurysm. Many conditions that cause peripheral nonperfusion can lead to a Coats’-like response with hard exudates, such as progressive facial atrophy, facioscapulahumeral muscular dystrophy, and retinitis pigmentosa. Our patient did not manifest systemic or ophthalmic manifestations that might suggest one of these diagnoses. Another diagnostic consideration is idiopathy retinal vasculitis, aneurysms, and neuroretinitis (IRVAN), which typically involves far more than a single quadrant of the retina.

Cryotherapy and laser photocoagulation can induce regression of the vascular anomalies in Coats’ disease. Anti-VEGF treatment can reduce the amount of exudate, but this does not treat the underlying condition. VEGF levels are increased in Coats’ disease, but they are not involved in the disease’s pathogenesis.(1) Without an acute threat to central vision, this patient’s Coats’ disease is being monitored.  Our patient has received anti-VEGF treatments in both eyes for the diabetic retinopathy, and panretinal photocoagulation might be done in the future.
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1) Sen M, Shields CL, Honavar SG, Shields JA. Coats disease: An overview of classification, management and outcomes. Indian J Ophthalmol 2019;67:763-771.