Central serous chorio-retinopathy (CSR) is a poorly understood eye disease. It affects the eye tissue which senses light (the retina). In CSR fluid spontaneously gathers under the retina. This can lead to permanent vision loss in about 1/3 of cases. Some cases spontaneously resolve but some persist for years, recur or affect the second eye. Each year there are 10 new cases per 100,000 men and 2 cases per 100,000 women in the population. The cause is unknown although it can occur in families and some genetic changes have been found. There are no proven treatments. Recently a few patients have responded to treatment with a drug called eplerenone. This drug removes the subretinal fluid and improves vision. However, information on the long term benefit and safety of this drug is lacking. To address this we will perform the first randomised, double-masked, placebo-controlled clinical trial of eplerenone in CSR to find out whether it is better than placebo treatment. We hope this will establish the first scientifically proven therapy for CSR. We will also study the basic disease process. We will determine what genetic variations are commoner in CSR patients. This should identify biological pathways which could be targeted to develop new drug therapys for the disease. We will model the disease in the laboratory. By taking patient skin samples we can create the type of cell that grows under the retina. This cell layer, called the retinal pigment epithelium (RPE), is thought to be faulty in CSR. By studying it we can find out what is different in the RPE of affected patients. We can also use these cells to study possible drug therapies. We can assess drugs more quickly this way than would be possible in a clinical trial and so should identify promising new treatments faster.