Retinal blood vessel disorder. Image 1 of 4. Fluorescein angiogram of a retina showing central serous retinopathy (CSR). This is a condition in which fluid leaks into the membrane underlying the retina, causing a blister-like area (dark spot, centre) to develop. Here it is on the macula (pale area), the area of the retina responsible for the sharpest vision. CSR causes distorted and blurred vision, and a blind spot may develop at the centre of the visual field. Many cases require no treatment, with the fluid being reabsorbed over time. For a sequence showing the injected fluorescein dye leaking into the blister, see images M155/471-474.