Answer
From question on page 211
The diagnosis was retinopathy secondary to interferon treatment. The fundus (fig 1) shows flame shaped haemorrhages, cotton wool spots, and blurring of the disc margin. Interferon and ribavirin were stopped prematurely. His hypertension was attributed to interferon, secondary causes having been excluded. One year later there was complete resolution of the retinal features and his blood pressure had normalised.
Retinopathy associated with the use of interferon alpha has an incidence of 6–13% and up to 86% in diabetic and hypertensive patients. The mechanism by which this occurs is unclear but an idiosyncratic reaction is thought to be responsible. The majority of patients are asymptomatic and have complete resolution of retinal features following termination of treatment. Awareness of retinopathy is mandatory to avoid irreversible visual loss. The role of screening for retinopathy has yet to be evaluated.
The combination of interferon and hypertension led to a more severe form of retinopathy in this case. It is possible that the pathogenic mechanism responsible for the retinopathy was responsible for the hypertension.