Age-related macular degeneration (AMD)

At the centre of the retina there is a patch only a few millimetres across — the macula. It is what you read with, what lets you recognise faces and pick out fine detail and colour. Over the years the tissue of the macula wears out, and the middle of the picture dims, blurs or drops out altogether, while everything at the edges stays as it was. That is why the condition almost never ends in total blindness, yet it takes away precisely the sight you use every waking minute. It usually starts after fifty and becomes more common the older a person gets.

What people notice first

The change arrives quietly: the other eye covers for the damaged one for a while, so it can take a long time to realise anything is wrong. Small things are worth paying attention to:

• reading needs brighter and brighter light, and under ordinary lighting the letters run together;
• single letters or syllables drop out of a line of text, so the line seems to break;
• straight lines — a door frame, a window, the grouting between tiles — look wavy or bent;
• a cloudy, grey or dark patch sits right in the middle of your gaze, while everything around it looks normal;
• faces are hard to recognise, even though you can make out the person's build and clothes;
• colours fade, and the eye takes a long time to adjust to dim surroundings after bright light.

There is no pain, the eye looks unchanged from the outside and it does not turn red — which is exactly why the condition is missed. One thing deserves a separate mention: people whose sight is badly reduced sometimes see patterns, figures, faces or whole scenes that are not there. This is not a mental illness but the visual cortex responding to a lack of signal, and the person knows the images are not real. It is worth telling the doctor, but there is nothing to be frightened of.

Dry and wet forms

Telling them apart matters, because they move at different speeds and offer different options.

The dry form accounts for around nine cases in ten. Drusen — dense deposits of fats and proteins — build up beneath the retina, the exchange of nutrients in that layer breaks down and the cells responsible for central vision die off slowly, over years and sometimes decades. In the late stage an area of lost tissue is left in the centre, and sight there cannot be brought back.

The wet form is less common but more dangerous. New, faulty vessels grow under the macula, leaking plasma and blood; the retina swells and lifts. Here things change over weeks and days rather than years, and this is the variant that most often causes severe loss of central vision. It nearly always develops on top of the dry form, so a reassuring diagnosis is not a reason to relax — it is a reason to keep watch.

What raises the risk

There is no single cause; several things add up.

• Smoking is by far the most important of the things you can change: among smokers the condition is several times more common and starts earlier. Quitting lowers the risk even after many years.
• Age and family history: the risk is higher if a parent, brother or sister had macular degeneration.
• High blood pressure, raised cholesterol, excess weight and inactivity — what damages the vessels of the heart damages those of the eye too.
• A diet short on vegetables, leafy greens and fish.
• A light-coloured iris and years of bright sun without eye protection.

Age and genes cannot be changed; everything else can, and that is the only prevention available today.

When waiting is not an option

Sight that fades slowly is a reason to book an eye appointment in the ordinary way. But some situations do not allow delay.

See an eye specialist within a day or two if straight lines have suddenly buckled, or if a dark patch in the centre has appeared over a few days and is growing. That is how the wet form announces itself, and treatment works better the earlier it starts.

There are also other problems, unrelated to macular degeneration, that need immediate care:

• vision in one eye disappears suddenly and painlessly, over seconds or minutes — that is how a blocked retinal vessel behaves, effectively a stroke of the eye;
• a sudden drop in vision in someone over fifty together with headache in the temples, a tender scalp when combing the hair and jaw pain on chewing — this can be inflammation of the temporal arteries, and without urgent treatment the second eye can be lost within days;
• flashes, a sudden shower of floaters, a dark curtain coming in from one side of the field of vision — signs of a detaching retina;
• severe pain in the eye, redness, coloured haloes around lights and nausea — an attack of glaucoma.

In these cases call your local emergency number — 112 across Europe — or go straight to an eye casualty service.

How the diagnosis is made

It starts with a check of visual acuity and an examination of the back of the eye: drops are put in to widen the pupil, and the retina is inspected. For several hours afterwards everything looks blurred and light is dazzling, so do not drive that day and bring dark glasses.

The key investigation is optical coherence tomography, which shows the retina layer by layer and picks up fluid and swelling before any change is noticed. If the wet form is suspected, images of the retinal vessels are taken as well, with or without a contrast dye. The same scans are later used to judge whether treatment is working.

What treatment can do

Macular cells that have already died do not come back, so the aim is to slow the process and hold on to the sight that remains.

For the wet form the main method is injecting drugs that block vessel growth — the anti-VEGF group — into the eye. The injection is given under anaesthetic drops and takes a couple of minutes: monthly at first, then at longer intervals guided by the scans. In most people vision is stabilised and in some it improves; the earlier treatment begins, the better the outcome. Laser and photodynamic techniques are used rarely now, as an addition.

For the dry form there is no drug that repairs the retina. There is, however, something proven: at the intermediate stage, and also when the other eye is already badly affected, certain vitamin and mineral formulations containing lutein and zeaxanthin slow the shift to the severe stage. One warning matters for smokers and recent ex-smokers: older formulations contained beta-carotene, which raises the risk of lung cancer in people who smoke. Read the composition and choose it with a doctor rather than picking up «eye vitamins» at random. Research into new treatments continues, and an eye specialist can say whether anything is available.

The Amsler grid and everyday life

The most useful thing to do at home is to check yourself with an Amsler grid — a squared sheet with a dot in the middle. Hang it somewhere visible and look at the dot from reading distance, wearing reading glasses and covering one eye. The lines should stay straight and even. If part of the grid wavers, darkens or vanishes, see a doctor without putting it off. Each eye has to be tested on its own: while the other one is working, the change goes unnoticed.

When central vision is reduced, simple things help: a bright, well-aimed reading lamp, illuminated and electronic magnifiers, large type and strong contrast on screen, audiobooks and screen readers, tactile markings on appliances. There is also specific training in looking slightly to one side of an object so as to use the healthy part of the retina. Driving is a decision for the doctor: with both eyes affected, or a marked loss in one, giving up is the usual advice, and the rules differ from country to country.

Online consultation: what it can do

Examining the back of the eye and scanning the retina need a face-to-face visit, but much of what surrounds that can be settled by video. A doctor can go through the scan report and the eye specialist's letter with you and explain what the stage and the injection schedule mean. From your description they can judge what is happening: ordinary age-related change, something for a planned appointment, or a situation that means travelling today. Two other frequent topics are choosing a vitamin and mineral formulation with your smoking history and other medicines in mind, and adapting the home once central vision has already dropped.

This material is for information only and does not replace medical advice.