Fifteen years ago, Lorna Blakeney thought she had a lump of mucus in her eye. “I was sitting reading a book after lunch and suddenly realised there was something in my left eye. I tried to blink and rub it away. I thought a night’s sleep would help. But in the morning, it was still there. I didn’t do anything about it for two weeks, which was stupid of me, especially as my daughter is an optometrist.”

Lorna’s daughter sent her mum straight to an ophthalmologist. “But it was too late. I was diagnosed with wet age-related macular degeneration (AMD); there was no treatment in those days and I was told there was an 82% chance that my other eye would go, too.”

Lorna’s daughter, Dr Sue Blakeney, is a clinical adviser at the College of Optometrists. She says that what happened to her mum is not uncommon. “Macular degeneration causes damage to the part of the retina responsible for central vision. It affects one eye first, so you often don’t notice it unless you close one eye at a time; you can be almost blind in one eye and not be aware of it.” Lorna is even more pithy: “You have two eyes – make sure you compare them. One is often stronger than the other, but if things change, get help.”

Ophthalmologist Pearse Keane of Moorfields eye hospital in London says that AMD is the most common cause of irreversible sight loss in the UK and Europe. “Every day in the UK alone, nearly 200 people develop the severe, blinding forms of AMD. There are two main forms of AMD – a ‘dry’ type and the ‘wet’ one. Wet AMD has nothing to do with watery eyes but is so-called because abnormal blood vessels grow under the centre of the retina (the nerve tissue that lines the back of the eye). These blood vessels leak fluid and bleed easily, and this can cause severe visual loss because it is such a sensitive area.”

Keane says that, until about 10 years ago, there was no effective treatment for the wet form of AMD, but now it can be treated with regular injections of drugs such as Eylea or Lucentis into the eye. They block the growth of new blood vessels and reduce the leakage of fluid from existing vessels. This improves sight substantially in about a third of patients and prevents further worsening of vision in about 95% of cases. However, the effects of the drugs last only one to two months, so people need frequent injections over long periods of time.

Andrew Lotery, a professor of ophthalmology at the University of Southampton, says everyone over 50 should at least be aware that if they have a loss of vision in one eye that is not corrected when they put on their glasses, then it could be rapidly developing wet AMD. “You should be seen in hospital within a week because scarring develops if wet AMD is left untreated.” Optometrists and ophthalmic practitioners (doctors trained to examine eyes) can look for early signs of macular degeneration and will refer on urgently if they are concerned. In the past, diagnosis relied on a slit-lamp examination – a contact lens put on the eye and observed through a microscope looking for thickening of the retina – and a fluorescein angiogram (FA), which involves an injection into a vein in the arm to highlight blood vessels in the eye. But “FA makes lots of people sick and occasionally causes severe allergic reactions,” says Lotery.

Happily, there is an alternative now. “The initial diagnosis of wet AMD, and the need for follow-up treatments, is determined with a form of retinal imaging called optical coherence tomography (OCT),” says Keane. OCT is a relatively new form of medical imaging, having been around since 1991. It is analogous to ultrasound except that it measures the reflection of light waves, rather than sound. Most people with known retinal disease have an OCT scan at every hospital eye clinic appointment and get offered more injections into the eye if there are signs of “fluid”.

Lotery says the price of OCT machines are coming down all the time although they still cost around £50,000 each. There are also now handheld OCTs, which some believe will make detecting eye disease as “easy as scanning a barcode”, but Lotery urges caution: “Don’t rush out to buy one. You still need a trained health professional to interpret the results – it’s easy to misinterpret them.”

Machines are also being trained in diagnostic techniques. Google’s DeepMind has used data from thousands of OCT scans to develop an algorithm that can diagnose wet AMD at least as quickly and effectively as eye specialists can. A partnership with Moorfields and the NHS will shortly publish more detailed results.

AMD develops as the eye ages – and Blakeney says other risk factors include a family history of AMD, smoking, excessive exposure to UV light and, possibly, to screens. Maintaining a normal weight may be protective and there is probably a role for foods that contain dietary pigments, such as blueberries and peppers. “There is no good evidence that the general population should take supplements, but if you already have AMD in one eye, it may be advisable.”

Dry AMD is less severe than wet, progresses over years rather than months and causes more gradual loss of central vision. “Unfortunately, there is no effective treatment for dry AMD, although there are many clinical trials under way,” says Keane.

The exciting developments in diagnosis and treatment of wet AMD have come too late for Lorna Blakeney. She is one of the 360,000 people in the UK who are registered as blind or visually impaired. Six years after her initial diagnosis, Lorna noticed that the venetian blinds in her bathroom window looked wiggly in her remaining sighted eye. “This time, I had injections of the drug Lucentis into my eye. I thought it would be a magic bullet; it is for many, but it wasn’t for me. Gradually, I lost the sight in the eye and I’m now registered as severely sight impaired, with only a bit of peripheral vision left.”

“There is life after AMD. I manage pretty well, with every gadget known to man.” She uses software on her phone and a tablet with “speaking” icons, has voice recognition software to dictate emails, a talking watch, clock, kitchen scales, measuring jug and microwave. One gadget rests on the edge of a mug and beeps twice; once for the water and once for the milk, to make a perfect cup of tea without spillages. Another clips on to her glasses and scans and speaks the writing on food labels in the supermarket. Lorna says all these aids are enormously helpful, but they don’t come cheap and most are not subsidised.

“If I go out on my own, I have a symbol cane to let other people know that I can’t see them although I have enough peripheral vision that I can move around without bumping into things. Not being able to read is biggest nuisance. One very posh British restaurant we went to had the French ‘mesdames’ and ‘messieurs’ in pale grey letters on a pale-green sign. I didn’t stand a chance.”