Many experts attribute cataract formation to the 'wear and tear' of age, but protein aggregation (where proteins accumulate and clump together) in the lens is a factor. Your lens – which is primarily made up of protein and water – needs to be clear for you to have a sharp, focused image of the world. As we get older, some of this eye protein can start to lump together, making the lens cloudy. This forms a cataract, and it can become bigger over time, making it increasingly harder to see clearly.
One theory is that activities such as smoking, heavy drinking and increased exposure to UV light can result in damage by free radicals – unstable oxygen molecules that can damage cells and accelerate the progression of disease – and appear to increase the risk. Some diseases and medication also make you more susceptible. Many studies suggest cataract formation could also be related to diet – eating less meat and/or increasing levels of antioxidant vitamins have both been suggested. For some, the condition is hereditary.
Cataracts build up over time and initially changes may not be noticeable, but as they get bigger your vision becomes misty, making it harder for you to read, drive, watch television or potentially recognise faces.
Colours appear less vivid and you will be more sensitive to sunlight and glare from streetlights or car headlights at night (you might also see a halo around these). You may also have double vision in one eye.
Needing frequent prescription changes to your glasses or lenses can also be a sign. The Royal National Institute for the Blind describes cataracts as feeling 'like your glasses are dirty and need cleaning, even when they don't.'
Your optician or optometrist can usually spot a cataract, and see just how much of the lens is affected, during a routine eye test. But if you are experiencing problems, do see your GP or optician immediately.
Who gets cataracts?
Cataracts are most common in the over 65s, but you can have age-related cataracts in your 40s and 50s, it's just that they tend to be smaller and not affect your sight. Men and women are affected in equal numbers.
You are at increased risk if there is a family history of cataracts, you smoke, drink heavily, or are overweight; or if you have spent long periods exposed to UV light or to radiation (e.g. from cancer treatments). Having diabetes, taking cholesterol-lowering statins, being on HRT for more than 10 years, and prolonged steroid use are other risk factors. Having an existing or previous eye condition such as glaucoma, or an eye injury also put you at higher risk of cataracts, as can being very short-sighted.
Cataracts can affect children – some babies are born with them, or they can develop in childhood – but tend to be so small they don't have any effect on their sight.
Cataracts are often improved by getting stronger glasses, brighter lighting and magnifying lenses. If they do not, there is no other treatment aside from surgery.
The most common surgical procedure is called intra ocular lens replacement which involves removal of the cloudy lens and replacing it with a clear artificial one made from plastic or silicone. This is now a very routine operation performed under local anaesthetic.
Research shows a plant-based diet rich in antioxidants like vitamin C and beta carotene, lutein and zeaxanthin (carotenoids found naturally in the human lens) can protect against cataract formation. A good lutein intake may make it less likely that cataracts develop. A review of six large studies found people with the higher intakes of lutein and zeaxanthin showed a one to three per cent reduction in their risk of three types of age-related cataracts.
The American Optometric Association say the antioxidant components of vitamin C may be able to slow or reverse cataract progression. A large study of female health professionals found higher dietary intakes of lutein, zeaxanthin and vitamin E from food and supplements were associated with a decreased risk of cataracts.