Retinal diseases: types, symptoms and treatment

Light entering the eye is focused on the retina. RNIB explains that rod cells handle dim light and side vision, while cone cells, packed into the central macula, handle detail and colour. Signals travel along the optic nerve to the brain. The retina can be harmed by traction or tearing, by damage to its blood vessels, by degeneration of the macula, or by gene changes that gradually switch off its cells.

These causes lead to different symptoms. Some conditions mostly affect side vision or night vision. Others mostly affect the middle of the picture. Knowing which kind of vision change you have helps an eye specialist decide where to look.

A detached retina is when the thin layer at the back of the eye becomes loose. The NHS lists floaters or flashes, a dark curtain or shadow in the vision, and blurred vision as symptoms. It says it is usually caused by changes in the jelly inside the eye with age, known as posterior vitreous detachment, and is more likely if you are short-sighted, have had an eye operation such as cataract surgery or an eye injury, or have a family history.

RNIB says only about 10 to 15 people per 100,000 have a retinal detachment each year, most often between 40 and 70, and about 1 in 8 people with a detachment develop one in the other eye. It advises having new symptoms checked within 24 hours and says a solid dark shadow moving across the vision means going to A&E straight away.

The NHS says treatment is surgery, such as vitrectomy, scleral buckling, pneumatic retinopexy or sealing a tear with laser or freezing treatment, usually under local anaesthetic. For 2 to 6 weeks afterwards vision may be blurred, and you may be advised not to drive, and not to fly after a gas bubble. You can get a detached retina more than once.

High blood glucose can damage the small blood vessels in the retina. The NHS says it is more likely if you have had diabetes for a long time or have high blood pressure or cholesterol. It usually has no symptoms at first. Later signs include worsening eyesight, blurred vision, floaters and difficulty seeing in low light.

The NHS describes three stages: background, pre-proliferative and proliferative retinopathy, plus a form affecting the macula called diabetic maculopathy. Early stages need monitoring only, while proliferative disease is referred for treatment. Options include laser treatment, regular eye injections of anti-VEGF medicine, a steroid implant and eye surgery. It states that sight loss already caused cannot be cured, so the aim is to stop it getting worse.

Screening is the key protection. The NHS says people with diabetes aged 12 or over are invited every 1 or 2 years, appointments last around 30 minutes, drops widen the pupils so sight is blurred for a few hours and driving afterwards is not possible, and gestational diabetes does not trigger an invitation.

Age-related macular degeneration (AMD) affects the central vision. The NHS says it usually first affects people in their 50s, and it has been linked to ageing, smoking, high blood pressure, being overweight and family history. Symptoms include a blurred or distorted area in the middle, straight lines looking wavy, sensitivity to bright light and sometimes seeing things that are not there. It is not painful.

RNIB describes early AMD, often found at a routine eye test through deposits called drusen, and two late forms. Dry AMD develops slowly. Wet AMD happens when new blood vessels grow under the macula and can change vision within days or weeks. The NHS says wet AMD is treated with anti-VEGF eye injections or light treatment, while there is currently no treatment for dry AMD, though support for low vision is available.

RNIB advises anyone with dry AMD who notices a sudden change to tell their optometrist at once, because it can turn into wet AMD, where sight-saving treatment may be possible.

These are genetic conditions in which retinal cells gradually stop working. RNIB says retinitis pigmentosa is the most common, usually affecting rod cells first, so the symptoms are night blindness, loss of side vision, glare and difficulty adapting between light and dark. Onset varies from early childhood to later life. Other dystrophies affect the cones or macula first, so central vision is affected earlier.

RNIB explains the inheritance patterns, which can be autosomal dominant, autosomal recessive or X-linked, and the chance of a child being affected differs in each. Genetic testing and counselling can help families understand their situation. RNIB's page also has sections on treatment, research and support.

Not every symptom is a retinal emergency, but some combinations are. The NHS advises getting help from NHS 111 if floaters suddenly appear or increase, if you see flashes of light, if a dark curtain or shadow moves across your vision, or if vision suddenly blurs. For AMD it adds an urgent optician appointment or NHS 111 for sudden worsening, a curtain or shadow, or a red, painful eye.

People with diabetes should seek advice for any sudden worsening of eyesight or new blurred vision, the NHS says. An optometrist can refer straight to an eye casualty or hospital eye service if a tear or detachment is suspected.

• New floaters, or a sudden increase in the ones you have.

• Flashes of light at the edge of your vision.

• A dark curtain or shadow moving in from one side.

• Sudden blurring or loss of vision in one eye.

• Straight lines suddenly looking bent or wavy.

Routine eye tests can pick up early retinal change before symptoms appear. Diabetic eye screening uses photographs of the back of the eye, and optometrists monitor early or dry AMD, and RNIB says home checking with a door frame, tiles or an Amsler grid may be advised between visits.

Where vision is reduced, low vision assessments, aids and practical support can help. RNIB offers practical and emotional support, and the NHS lists support from diabetes teams and charities such as Diabetes UK for retinopathy. Private ophthalmology services also exist alongside NHS care.