As we grow older, our eyes change and sight may deteriorate. Older eyes are also more vulnerable to disease, much of which is preventable. Lilian Anekwe reports on the lifecycle of seeing
Eyesight is often one of the first senses affected by ageing. As we age, there are key changes that take place in the eyes which can impair our vision.
The pupil, which controls the amount of light that reaches the retina, becomes smaller and less responsive to changes in light – the eye of a 20 year old can receive as much as 16 times more light than that of an 80 year old.
This can affect vision in several ways. Seeing well in dim light becomes harder, we are less able to adjust to glare and it becomes more difficult to adapt from darkness to bright light or vice versa.
As we age the lens of the eye begins to lose elasticity. In the same way that losing flexibility in tendons and muscles makes it more difficult for the body to move, losing lens elasticity makes it harder for the lens to bend and focus our eyes.
Changes that lead to the development of eye diseases are an inevitable consequence of living and breathing
Also, the fluid inside the vitreous humour, which makes up about four fifths of the eye, becomes more watery and strands of a protein called collagen can form within it – these can sometimes be visible as “floaters”.
But these changes are distinct from the eye diseases that can also commonly occur in older age. John Nolan, principal investigator in the macular pigment research group at the Waterford Institute of Technology in Ireland, says the changes that lead to the development of eye diseases are “an inevitable consequence of living and breathing”.
For example, a combination of age and the environment contributes to the development of age-related macular degeneration (AMD) – damage to the spot near the centre of the retina and the leading cause of age-related blindness.
Dr Nolan explains: “AMD is caused by free radicals [unstable molecules] damaging the cells in the macula. As we get older, our ability to defend against and repair the damage caused by the free radicals diminishes and the free radicals that we are exposed to daily build up over the course of a lifetime. Both these things contribute to the development of AMD.”
Similarly, with cataracts, Dr Nolan says the blurred vision that people with a cataract experience is caused by the cells in the lens “becoming damaged by the oxygen we need to stay alive”. These changes cause the protein fibres in the lens to break down and clump together, which clouds the lens and leads to a loss of vision.
For older people diagnosed with eye diseases, the future is increasingly promising. Many ophthalmologists are now able to use a technique called optical coherence tomography (OCT) imaging, which creates a 3D image of the eye that can spot the progression of many common eye diseases of old age much earlier than ever before.
Krysten Williams, general manager of Heidelberg Engineering, a leading manufacturer of OCT machines, says: “The advanced treatments that have become available and are in development for eye diseases have made it necessary to have advanced imaging techniques. OCT imaging can allow an ophthalmologist to see and identify exactly where treatment is required, down to one thousandth of a millimetre of change – far earlier than a person will notice any change or loss of vision.
“The images are more obvious and easier to interpret than traditional, two-dimensional imaging techniques. They are designed to augment and complement existing technology to allow eye diseases to be diagnosed and monitored much earlier.”
As well as AMD, other eye diseases that affect older people, such as glaucoma – a group of eye conditions caused by changes in eye pressure and the second most common cause of blindness worldwide – and a complication of diabetes that affects vision called retinopathy, are benefitting from these advances in technology which could prevent sight loss.
Rebecca Sheehy, older people impact team manager at the Royal National Institute of Blind People (RNIB), stresses that vision loss can be traumatic, but there is help available. “If people do find that they have vision loss, it does not mean that they can’t continue to do many of the things they have always done and been used to. The RNIB can offer emotional support and advice about the many aids that are available, which can help people with sight loss have an active, fulfilling life.”
Time to keep an eye on disease
VISION AFTER 40 Reaching the age of 40 can be a critical time for eye health. So, as Lilian Anekwe explains, it’s best to get your eyes checked
One in nine people over 60 have some degree of sight loss and this increases to one in three people over 85.
But some sight loss can occur as early as 40 – most commonly presbyopia, a loss of our ability to focus the eyes. Which is why Rebecca Sheehy, older people impact team manager at the Royal National Institute of Blind People (RNIB) says that at any age “an eye health check is really important because you may well be having sight loss without knowing it”.
Eye examinations test more than just your sight. Dr Sue Blakeney, clinical adviser for the College of Optometrists, says: “Optometrists will test your vision. But we will also check your eye health: this means checking the front of your eye which can pick up high cholesterol, and the insides of the eye where we can detect eye diseases like cataracts and AMD.
Some sight loss can occur as early as 40, most commonly loss of focus
“If you’re over 40, we may also test the blood pressure inside the eye, which can detect glaucoma and, if your optometrist thinks you need it, they’ll also arrange for a visual field test, which can pick up glaucoma as well as much rarer diseases such as brain tumours.
“You shouldn’t have to ask for these tests as, with the exception of the visual field test, they are all offered by good high street opticians. But if people think they need a test, they shouldn’t be too shy to ask, even in between their regular eye tests.”
There’s plenty you can do to reduce the risk of eye disease and boost eye health in your 40s and beyond. Ms Sheehy says: “Many people don’t know but the link between smoking and AMD is as strong as the link between smoking and lung cancer, and stopping smoking can greatly reduce the risk.
“In addition, eat a varied diet, with plenty of fruit and vegetables, and keep to a healthy weight. If you have diabetes and high blood pressure, it’s important to manage these well, and also keep your eyes covered in the sun, as UVA and UVB rays in sunlight can damage the eyes over time.”