At the front of the eye you have the eyeball surface, made up of several layers, and the lens, that lets you focus images on the back of the eye. With age (usually from your 40s) your lens becomes less efficient at focusing, accounting for the inevitable middle-age glasses. On the inner surface of the eyeball is the retina, packed with light-detecting cells.

Cataratta

Perhaps the best-known lens problem is a cataratta, where the usually clear lens of the eye becomes cloudy. This means you're basically looking through frosted glass, so the gradual loss of vision can't be corrected with spectacles.

You may also notice spots on your vision; haloes around bright lights; and problems seeing in well-lit environments. About 1 in 3 over-65s of both sexes have cataracts, which can affect one or both eyes. Fortunately, a simple day-case procedure under local anaesthetic allows your eye surgeon to replace the lens, usually with great success.

Your eyeball is full of nourishing fluid called aqueous humour. This is constantly topped up, with the excess drained away through a meshwork at the front of the eye. If you have glaucoma, the pressure inside your eyes is raised because of a mismatch between the amounts of fluid being produced and naturally removed.

Left untreated, this build-up of pressure can damage your 'seeing' (optic) nerve and lead to gradual loss of vision. By the time you get symptoms, you can have significant permanent problems. Worse still, sometimes the fluid outflow gets completely blocked, leading to the severely painful red eye of glaucoma acuto. Without emergency treatment, this can lead to permanent vision loss.

Fortunately with early diagnosis and regular long-term eye drops, damage can almost always be avoided - but clearly it needs to be diagnosed. Glaucoma is common, affecting 1 in 50 over-40s and 1 in 10 over-75s. Your risk is higher still if it runs in your family, you are very short-sighted or you have diabete. Everyone should have regular eye checks every two years at least. But if glaucoma runs in your family, you're entitled to free NHS eye checks every year to rule this out.

Another eye problem relating to ageing is age-related degenerazione maculare, or ARMD. Your macula is a small area of your retina with the highest proportion of light-detecting cells for seeing fine detail. With age, this area can become less efficient, making ARMD the most common reason for severe sight loss in over-50s. However, it doesn't cause complete loss of vision.

There are two main kinds of ARMD. About nine in 10 people have the 'dry' variety, which can't be treated but which tends to progress much more slowly. The 'wet' kind can cause more rapid vision loss, but can be treated with injections into the eye under local anaesthetic.

It's essential to protect your eyes, even if you don't have symptoms. It's never too early to get into the habit of wearing sunglasses with good UV protection whenever you're in bright light. And an eye check with your optician at least every two years (more often if advised) can pick up treatable problems you may not know you have.

Fumare increases your risk of ARMD, as well as cataract, so it's just one more reason not to do it. Keeping your blood pressure under control (with tablets from your GP if needed) and keeping your weight within normal limits will both reduce your risk of eye problems. So will a healthy balanced diet, with plenty of frutta e verdura. And of course, these same measures will protect your heart and cut your risk of stroke - what's not to like!

Thanks to My Weekly where this piece was originally published.