The importance of eye tests
Next time you get your eyes tested, you may enjoy cutting-edge technology as part of the appointment. Ocular computed technology is being introduced to take 3D pictures of the retina, helping optometrists to detect swelling which may indicate age-related macular degeneration or AMD.
Chances are, though, you’ll start with a peek at a Snellen chart, the familiar series of letters of differing sizes, developed in 1862.
Don’t be disappointed as traditional eye tests, which enable optometrists to support the clearest, most comfortable vision in all of us, are yet to be surpassed.
The more modern tests, however, come into their own to protect us against permanent sight loss and even detecting health problems of a more serious nature.
But poor uptake of regular sight tests is probably the biggest risk to the nation’s eye health. According to the Eyecare Trust, an eye health charity, 20 million of us fail to have our eyes checked once every two years, as recommended, and one in ten have never had an eye test.
So what does a modern eye test involve? Susan Blakeney, College of Optometrists’ spokeswoman and a practising optometrist in Kent, explains: “The main thing we do is check your vision; the lens in the eye becomes stiffer with age, so everyone will experience some change and probably need help for reading if nothing else. But we also check that your eyes are aligned and work well together.”
However, making sure your focus is perfect isn’t the only point of a sight test. “We have a duty to examine your eyes from a health point of view when we carry out a sight test. This means checking for early signs of macular degeneration or glaucoma,” says Dr Blakeney.
AMD is the leading cause of visual impairment in the UK, affecting up to 500,000 people to some degree, according to the NHS.
Although there is no treatment for the main type of AMD or dry macular disease, the Macular Society provides information and support which helps people cope. Anyone whose vision deteriorates very quickly, with the appearance of wavy lines, should seek immediate care through A&E as this would suggest the onset of wet AMD, which is treatable if caught in time.
Glaucoma, however, which affects about 480,000 in England, with those of black-African or black-Caribbean origin most at risk, can be treated more easily using eye drops, lasers and even surgery. Early detection matters though as any damage caused is irreversible.
“We test for glaucoma using a puff test, which measures pressure in the eye. And we look at the nerve at the back of the eye using an ophthalmoscope, which has a bright light and strong lens,” says Dr Blakeney.
When optometrists look into the eye, they can see all its structures – from whether a cataract is developing to retinal damage, which might point to AMD, or even swelling, which could indicate a brain tumour.
Some 20 million of us fail to have our eyes checked once every two years
A visual field test, which measures peripheral vision, is also carried out. Having an adequate field of vision is a requirement for a British driving licence.
Some patients will be used to having a photograph taken of the back of the eye. “It’s an objective record of what things look like,” explains Dr Blakeney. Now ocular computed tomography is becoming more common and will be particularly useful for spotting swelling in the macular region, suggesting the start of AMD.
But eye tests aren’t just important for vision or specific eye-related health issue. Using an ophthalmoscope, optometrists can examine blood vessels to see if any capillaries have thickened, narrowed or burst, which would be due to high blood pressure.
If the damaged capillaries are in the retina – known as retinopathy – it could indicate diabetes, with high blood sugar the culprit behind swelling, leaks of fluid into the eye and burst vessels.
Both conditions are much more likely to be detected in your GP’s clinic, says Dr Blakeney, adding “only blood tests are definitive”, but high blood pressure, in particular, should be monitored.
Dale Webb, director of research and information at the Stroke Association, explains: “High blood pressure is a leading risk factor and contributes to over half of all strokes in the UK.
“It puts a strain on all blood vessels, including the ones leading to your brain. This makes a blockage more likely to develop or a blood vessel in the brain to weaken and bleed, both of which could cause a stroke.”
Dr Webb adds: “Visual problems are a huge issue; 60 per cent of stroke survivors will be affected, with problems such as loss of central or peripheral vision or impaired eye movement.
“Unfortunately, we know that one in three stroke survivors aren’t warned this could be a problem or that there is treatment to help. So it’s worth talking to your optometrist if you’re concerned. They can provide information, basic screening and refer you back into healthcare via your GP to a specialist orthoptist in hospital.”
CHILDREN’S EYE HEALTH
Optometrists could also pick up a serious disease in children: retinoblastoma or eye cancer, which affects up to 50 under-fives every year. Ashwin Reddy, paediatric ophthalmologist at Barts Health NHS Trust and medical adviser for the Childhood Eye Cancer Trust (CHECT), says: “Usually parents notice something white at the back of the eye or a squint; if so, it’s essential they take their child to a doctor to be assessed.”
But he adds: “A GP may see one case in their entire career. Sometimes referrals come via an optometrist as there is a protocol, established by CHECT, which encourages everyone who works at an optician’s to be alert to the symptoms. If a child has a white or unusual reflex at the back of the eye, they must be seen by a specialist as soon as possible.” The white appearance may be a tumour or a cataract reflecting light back.
Prompt treatment can be successful, with a 98 per cent success rate, according to CHECT, and early intervention increases the chance of the eyeball – and even vision – being saved.
Mr Reddy points out: “We don’t recommend vision screening in the under-fives for children without symptoms, but parents should be alert to children complaining of headaches or vomiting as this can indicate a brain tumour, which can be diagnosed through an expert eye test as the eye acts like a window to the brain.
“By age five, every child will be entitled to a vision test through their school and, at this point, uneven vision – amblyopia – may be picked up. If one eye is working better than the other, the child may be referred to a paediatric ophthalmologist for patching, so the ‘good’ eye is covered up, to strengthen the weaker eye. An optometrist might also spot a squint and refer that to a specialist.”
Dr Blakeney concludes: “Most people will benefit from a sight test every two years, especially once you’re over 40 as the risk of glaucoma increases, which left unchecked can steal your sight without you knowing it. We can make sure your eyes are healthy – and your vision is as clear and comfortable as possible.”