What is central serous retinopathy (CSR)?
This condition, sometimes also called central serous chorioretinopathy (CSC or CSCR), involves the accumulation or leakage of fluid beneath the macula, which is the part of the retina responsible for central vision.
What are the symptoms of CSR?
Most patients experience distortion and/or blurring of central vision in the affected eye. Sometimes both eyes can be affected.
What causes CSR?
Nobody knows exactly, and in the vast majority of patients there is no underlying cause identified. However CSR has been associated with a group of hormones known as glucocorticoids (a type of steroid, but frequently referred to as corticosteroids or simply “steroids”). These are released internally by the body during periods of stress; they are also abnormally elevated in a rare disease called Cushing’s disease. Finally glucocorticoids are also prescribed for a variety of diseases including inflammatory arthritis, asthma, and auto-immune disorders. Any of these causes of raised glucocorticoid levels in the body (stress, Cushing’s disease, or prescribed steroid medication) has been associated with a higher risk of CSR. However, since most patients with CSR have no underlying medical problem, it is not necessary to investigate all patients with CSR for rare disorders like Cushing’s disease.
What tests are used in CSR?
The amount of fluid leakage can be accurately monitored with OCT scanning. OCT can also detect unusual complications of CSR, including choroidal neovascularisation. Fluorescein angiography is often helpful in determining whether there is a focal leak that could be amenable to laser treatment. Sometimes, a different type of angiogram, using a green dye called indocyanine green (ICG) is used.
How is CSR treated?
Many cases of CSR will resolve spontaneously over a period of 2-4 months, so after a patient first presents with the condition, observation alone is a reasonable course to follow. Persistent cases may require further investigation and treatment. If angiography documents a focal leak (“hot spot”) which is not too close to the foveal centre (the most central part of the retina) then retinal laser treatment can often work well in reducing the leakage and causing resolution of fluid beneath the macula. If however there is a more diffuse problem – usually ascribed to the layers behind the retina known as the retinal pigment epithelium and choroid respectively – then further investigation with ICG angiography may be appropriate. Many studies have shown that eyes which demonstrate late ICG ‘hypercyanescence’ can benefit from a treatment known as photodynamic therapy (PDT). Finally, in recent years a certain group of medications which act on the body’s renin-angiotensin system (for example, eplerenone) have shown good efficacy in treating CSR, although they can occasionally have metabolic side-effects and may require monitoring with blood tests.
What is PDT?
PDT was originally developed to treat wet macular degeneration, but since that condition now has more effective treatments, PDT is actually used more often for other conditions – principally polypoidal choroidal vasculopathy (PCV) and CSR. In PDT, a special light-sensitising dye called verteporfin is injected into the patient’s vein. Then, a laser light of a very specific wavelength is shone onto the area at the back of the eye that needs treatment. This wavelength of light activates the verteporfin and a chemical reaction occurs which can help to close leaky blood vessels. In CSR, investigators have documented good results from using half of the normal dose of PDT treatment (sometimes called ‘half fluence’ PDT).