Central serous retinopathy (CSR): symptoms, causes and treatment

The macula is the central part of the retina and is responsible for sharp, detailed vision such as reading, recognising faces and driving. In CSR, RNIB explains, fluid leaks from behind the retina and collects under the macula, causing it to swell and the vision to be blurred and distorted. It usually occurs in one eye but can sometimes affect both.

The condition is also known as central serous chorioretinopathy (CSCR). The Macular Society says that sometimes the macula may lift up and become completely separated from the tissue behind it, and that the fluid can change how colour is seen.

Moorfields says the most common symptom is a blurred or distorted central vision in one eye. The Macular Society notes that not everyone has symptoms, that they can change from day to day, and that you should arrange to see an eye specialist as soon as you can if you notice changes.

• Blurred central vision.

• Straight lines that look wavy or distorted.

• A dark grey patch or dark spot in the centre of vision.

• Colours that look duller or less bright.

• Objects that look smaller than they should (micropsia).

• Increased sensitivity to light, or difficulty seeing an object against a similar background.

RNIB says that in most cases doctors cannot find a cause, which is called idiopathic CSR. Moorfields likewise says the exact cause remains uncertain. Several factors are linked with it.

RNIB lists a Type A personality, steroid medication, pregnancy, Cushing syndrome, H. pylori infection, sleep apnoea and untreated high blood pressure. Cortisol, the stress hormone, is thought to be involved: RNIB says high cortisol over time can make blood vessels more fragile and leak, although it is not thought to be the only reason. Moorfields notes that steroids taken orally, inhaled or applied to the skin have been associated with CSR.

The Macular Society says some studies suggest that a family history raises the risk. The Macular Society advises minimising the use of corticosteroids if you can, and says never to stop taking a medicine without speaking to a doctor, as stopping suddenly can cause health problems.

The Macular Society says it can be difficult to tell CSR apart from other eye conditions, so an eye specialist will run tests. An optical coherence tomography (OCT) scan, a painless 3D picture of the retina that can also be done at an optician, shows retinal thickness and fluid in the layers.

Other tests may include fluorescein angiography, in which a dye is injected into the arm to show where fluid is leaking from, and indocyanine green angiography. The Macular Society says the dye can stain the skin and colour the urine temporarily.

If you wait and see, repeat tests are used to check the fluid is going away.

RNIB says most people with CSR do not need treatment and will be monitored as it recovers, usually within the first six months. Treatment may be recommended for CSR lasting longer than six months, according to RNIB, and the Macular Society says most people experience symptoms for four to six months and may need treatment if it does not go away after that.

RNIB says episodes of CSR that last a long time or keep coming back are more likely to cause permanent changes to vision, and that in a small number of people it becomes chronic, with damage to the retinal pigment epithelium. These treatments aim to reduce or resolve the fluid but cannot restore damaged cells.

The Macular Society suggests reducing stress, getting regular exercise and enough sleep, and minimising corticosteroid use where possible, and says that finding CSR early helps to prevent permanent changes. RNIB says that if the affected eye is your better eye you may need low vision aids or a low vision assessment, which you can ask your ophthalmologist, optometrist or GP about.

Any sudden change in central vision should be assessed promptly. The Macular Society advises seeing an eye specialist as soon as you can. The Macular Society notes that an OCT scan can be done at an optician's practice, so a community optometrist is a sensible first step. If you lose vision suddenly, treat it as urgent and contact an optician, an eye casualty department or NHS 111 the same day.