Macular degeneration

What the macula does, and what goes wrong

The retina lines the back of the eye, and at its centre is a small area called the macula. It is the part responsible for detailed vision — reading, recognising a face, threading a needle, seeing colour properly. Everything outside it handles the broad view: movement, shapes, getting about.

Age-related macular degeneration is deterioration of that central patch. The effect follows directly from what the macula does. Detail goes, the periphery stays, and the result is a very particular kind of sight loss.

It does not cause total blindness

This deserves saying early, because a diagnosis frequently lands as though it meant going blind, and it does not.

Macular degeneration affects the centre of vision. Peripheral vision is not affected and is generally retained. Someone with advanced AMD may be unable to read a book or recognise a face across a table, while still moving around a familiar room without difficulty.

That is a serious loss and there is no point minimising it. But it is a different thing from darkness, and the practical help available is built around exactly this pattern — techniques for using the healthy retina around a central blind spot, magnification, and technology that reads print aloud.

The two forms

Dry AMD is much the commoner. Fatty deposits called drusen accumulate at the back of the eye and the macula thins and deteriorates over years. It is slow. There is no treatment on the NHS for the dry form itself, which sounds worse than it is in practice, because the pace means many people retain useful vision for a very long time.

Wet AMD is less common and behaves completely differently. Abnormal blood vessels grow beneath the retina and leak fluid and blood, which damages the macula quickly — over days or weeks rather than years. It can develop in someone who already has the dry form.

The difference in tempo is the practical heart of this. Dry AMD is monitored. Wet AMD is an urgent matter, and the gap between those two responses is why the next section is the most useful part of the article.

Straight lines going wavy

Early AMD often produces no symptoms for years. When symptoms do come, these are the ones:

• a blurred or distorted patch near the centre of vision
• straight lines looking wavy, bent or crooked — door frames, window bars, lines of text, tiles
• difficulty recognising faces
• a dark or empty spot in the middle of vision
• colours looking less bright, and objects sometimes appearing smaller than they should
• needing much more light than before to read

It is not painful and the eye looks entirely normal from the outside, so there is nothing for anyone else to notice.

The second item in that list is the one to act on. Straight lines suddenly appearing distorted is the classic sign of wet AMD, and it warrants an urgent appointment rather than waiting for the next routine one. Treatment works considerably better when it starts early, and with a condition that can progress within days, the delay between noticing and being seen is one of the few things anybody can influence.

A sudden worsening of vision, or a dark curtain or shadow across the field of view, needs seeing urgently too — though a curtain is more suggestive of retinal detachment, which is a different emergency with the same answer: be seen today.

Checking each eye separately

AMD frequently starts in one eye, and this is where it hides.

With both eyes open, the good eye fills in what the affected one is missing, so substantial loss can go entirely unnoticed. People routinely discover it by accident — covering an eye for some unrelated reason and finding the other one has a hole in the middle.

The remedy is simple and takes seconds: cover each eye in turn, look at something with straight lines, and compare. Anyone with AMD in one eye, or at risk of it, is usually advised to do this regularly. It is the only way the second eye gets caught early.

Who is at risk, and the one thing that can be changed

Age is the main factor, and it becomes considerably more common after 65.

Beyond that: a family history, high blood pressure, being overweight, a diet low in fruit and vegetables, heavy drinking, and exposure to ultraviolet light.

More women are diagnosed than men. The likeliest explanation is simply that women live longer, rather than any difference in susceptibility, and some sources list female sex as a risk factor on the strength of the diagnosis figures alone. It is worth knowing which of those two statements is being made.

Smoking is the significant risk factor that can actually be changed, and the effect is large. Smokers are reported as up to four times more likely to develop AMD than non-smokers. Stopping after a diagnosis may still slow progression, which makes it worth raising even late.

Treatment for wet AMD

This is where the outlook has changed beyond recognition, and it is worth saying plainly because older information is bleak in a way that is no longer accurate.

Wet AMD is treated with anti-VEGF drugs, given as an injection into the eye, typically every one to two months at first. The drugs block the signal that drives the abnormal blood vessels to grow.

The results: around nine in ten people have their vision stopped from getting worse, and around three in ten see an actual improvement. Twenty years ago neither outcome was available at all.

The prospect of an injection into the eye alarms people considerably more than the reality warrants. It is done with anaesthetic drops and takes moments. Side effects are usually minor — redness, a gritty sensation, small bleeds on the surface of the eye. Where injections alone are not enough, photodynamic therapy, a light treatment, can be added.

The commitment is the real cost: this is ongoing treatment with regular hospital appointments, not a course that finishes.

Dry AMD, and the supplement question

There is no treatment for dry AMD on the NHS. What exists is monitoring, to catch any conversion to the wet form early, and the low vision support described above.

Nutritional supplements are where most of the confusion sits, and the honest position is more specific than either the marketing or the dismissal suggests.

A particular formulation of antioxidants and zinc, developed through large trials and generally sold as an AREDS2 formula, is typically recommended for people who already have intermediate or advanced dry AMD. It is not a cure, it does not restore lost vision, and it is not an NHS-endorsed treatment. Equally, it is not the same thing as a general eye vitamin, and the evidence behind it is not nothing.

Two things follow. Anyone with dry AMD should raise supplements with their ophthalmologist or optometrist rather than choosing from a shelf, because the formulation and the stage both matter. And anyone without AMD has no established reason to be taking these at all — they are a management option for an existing condition, not a preventive measure for the general population.

Diet is a different matter and a more useful one: plenty of fruit and vegetables, controlled blood pressure, a healthy weight, and not smoking. None of that reverses damage already done, but it is the version of this with evidence behind it.

Getting it found

AMD is detected by examining the back of the eye, which is a standard part of a sight test. Drops may be used to widen the pupil, which blurs vision for a few hours afterwards, and an optical coherence tomography scan gives a cross-section through the layers of the macula where the early changes show.

NHS sight tests are free for anyone aged 60 or over, which covers most of the population at risk. Suspected wet AMD is referred urgently.

One more thing worth knowing, because it causes disappointment: a cataract can be removed successfully from an eye that also has macular degeneration, and the person may still see poorly afterwards. The cataract was not the only thing limiting their sight. That is worth establishing before surgery rather than discovering after it.