Retinal blood vessel disorder. Ophthalmoscope view of a retina showing central serous retinopathy (CSR). In this condition, a blister-like area (dark spot, centre) develops on the macula (large dark area) of the retina. The blister is formed by the leakage of fluid into the membrane underlying the retina. The macula is the area of the retina responsible for the sharpest vision. The blister causes distortion and blurring of the centre of the visual field, and a blind spot may develop. In some cases, this damage can be permanent. Many cases require no treatment, with the fluid being reabsorbed over time. Anti-inflammatory drugs and laser surgery can be used in severe cases.