Miércoles 26 de Noviembre de 2008, Ip nº 256

What your eyes tell you about your health
Por Simon Crompton

Eyes, they say, are the windows of the soul, but technological advances mean that they are rapidly becoming windows to our hearts, arteries, brain and nerves, too.

Tests offered by high street opticians and optometrists have always been useful for spotting eye diseases such as glaucoma, cataracts and macular degeneration, and some other conditions such as diabetes, which can be detected by tiny bursts in the eye's blood vessels. But now, if you're prepared to pay extra, some opticians are offering high-tech tests involving laser scanning, digital photography and computerised assessment of your eye's structure that can help to give an early diagnosis of other health problems too.

More than half of all sight loss is due to preventable causes and experts believe that up to a quarter of people with undiagnosed diabetes would have the condition spotted if they went for an eye test. Traditionally, the optician has found ill-health hotspots by peering into your eye with a hand-held light/magnifier (an opthalmoscope). But now, new advanced instruments are making eye examinations not just more accurate but capable of diagnosing a much wider range of conditions.

The eye has untapped potential as a means of diagnosing illness early because it is the only place in the human body where internal blood vessels and nerves can be viewed working undisturbed. High-quality images produced by these new techniques improve the chances of detecting conditions such as high blood pressure, heart disease, multiple sclerosis, stroke, diabetes and brain tumours through a simple eye check.

“Opticians have long been very good at assessing the front of the eye for problems like cataracts,” says Andrew Coombes, a consultant eye surgeon at Barts and the London NHS Trust. “But it's been more difficult with the equipment they've had to carefully examine the back of the eye, in particular, the whole retina and the point where the optic nerve joins it. The digital imaging techniques now available allow us to examine these vital structures at our leisure. A lot of opticians are embracing this and have exploited its commercial and diagnostic potential.”

High-resolution images of the retina at the back of the eye can reveal breaks or abnormalities in blood vessels that might suggest circulation problems or hypertension. Inflammation of the optic nerve can sometimes indicate multiple sclerosis. Small blobs of cholesterol in the retina can indicate high stroke risk. Coombes has received referrals from opticians using high-tech scanning techniques, who have been concerned by swelling at the back of the eye, the sign of a possible brain tumour, or signs of glaucoma (damage to the optic nerve caused by high pressure in the eye). “People shouldn't be frightened into having these tests, but they can provide a lot of reassurance,” he says.

It's an extra reason for having an eye test, at a time when sight organisations are concerned that too many of us are skipping them. A recent survey by Action for Blind People found that one in four adults hadn't had an eye test in the past two years, and the same proportion were unaware that an eye test could prevent them from losing their sight.

The research base demonstrating the advantages of these 21st-century techniques is growing, but not extensive. Though they're by no means available on every high street, they are becoming more widely embraced by opticians, and they are likely to become more easily available (see panel for details of how to find out about them).

I went to try out some of the techniques available at the Central London eye clinic of Charles Babumba, an optometrist for 25 years who trained at Moorfields Eye Hospital in London (www.cityeyesopticians.com). Over the course of an hour I was moved around the clinic from machine to machine, positioning my eye in the right place as directed. They're basically painless, though some of them do involve bright lights and lasers being directed into your eye, which can be mildly disturbing (though Babumba reassures me that it's perfectly safe). At the end of the tests, Babumba took me through the fabulously colourful scans and graphs at his computer. Despite having a retina that has become slightly darkened, possibly because of overexposure to sunlight, I'm assured that this is harmless and I'm all clear.

These tests don't come cheap. Whereas a “standard” eye test can cost as little as £15, you could pay more than £100 to have a full eye MoT using the latest techniques. But when I finally get the all clear, it gives me a little reassurance that not only are my eyes healthy, but basically I am too.

The Optomap panoramic retinal scanner

What? A laser scan of the whole of the eye's retina, producing a high-definition, multicolour image.

Why? Scans can reveal the beginnings of a detached retina, retinal holes, macular degeneration, high blood pressure and blobs of cholesterol in blood vessels that might indicate high stroke risk. The images provided by Optomap provide a permanent record of virtually the full surface of the retina, whereas an optician can see only a small central part of the retina at eye examination, unless he or she dilates the pupils with drops, which is uncomfortable and inconvenient.

What's it like? Pressing your eye into the opening on the machine and then positioning it correctly isn't easy, and the bright red light of the laser scan into your eye is scary, leaving a strong after-image. But the images are stunning when revealed on the computer, and I'm reassured by the optometrist Charles Babumba that my retina looks fine.

Where? There are dozens of Optomap providers in the country. Go to www.optos.com/uk to find them.

Humphrey visual field analysis

What? A kind of virtual star chamber, designed to check your field of vision. With one eye covered, you perch your head on the edge of a white hollow. As you stare at a central spot, tiny white lights go on and off randomly at the edge of your vision, and you have to click a button each time you see one. The computer calculates how many you managed to spot, and where.

Why? Unusual blind spots can indicate eye conditions like glaucoma, diabetes, macular degeneration. Charles Babumba has picked up early signs of neurological disorders and brain tumours, which can cause blind spots.

What it's like? A bit like playing a 1980s computer game, but it's tricky concentrating on that central spot.

Where? Already widely available in opticians around the country. Phone them to check.

Laser Polarimeter (GDX)

What? Another type of laser scan of the back of the eye, Designed to diagnose glaucoma by measuring the thickness of optic nerve fibres, which become damaged if eye pressure rises. You press your eye against an eyepiece and look at a flashing red dot, while at the control panel the optician targets your optic disc (where the optic nerve meets the retina) and takes a detailed image of it.

Why? Glaucoma is difficult to detect in its early stages, but this imaging provides the earliest indication of damage.

What it's like? Vaguely uncomfortable but less alarming lights than the Optomap.

Where? Available at a handful of opticians; contact the manufacturer Zeiss, 01707 871231.

Corneal topographer

What? This machine maps the contours of your cornea, the outer covering of your eye in front of your iris. It's a computer linked to a small illuminated bowl with a pattern of orange concentric rings in it, which is moved towards your eye.

Why? The cornea is one of the eye's lenses, so irregularities in its shape can cause sight problems that need to be corrected with lenses, spectacles or laser surgery. But the cornea can also be affected by serious conditions such as keratoconus, which can cause blindness, and picking up irregularities early can prevent the condition from worsening.

What it's like? Nothing to worry about, even though it looks as if a heated oven ring is coming at you.

Where? Available at opticians and opthalmologists around the country including the Kings Cross Eye Clinic, www.kcec.co.uk; Linklaters in Kent, www.linklaterwarren.co.uk ; and CityEyes, www.cityeyesopticians.com .

Digital retinal photography

What? A high-resolution, digital photograph of the central 30 degrees of the retina, the important part that includes the optic disc (where the optic nerve joins the retina) and the fovea (the central part of the macula, the most sensitive part of the retina).

Why? Like Optomap, this is useful for detecting diabetes, macular degeneration, and optic nerve problems.

What's it like? You just place your chin on a rest in front of the camera, there's a flash, and that's it. The after-image of the flash, though, remains for a few minutes.

Where? Available from many optometrists/ opticians, including Molsom and Associates in Lincoln (01775 713366), David Snow in Kent (www.sightonline.co.uk ) and Wooding (www.woodingopticians.co.uk )

Eye tests - what you should know

In England and Wales, routine eye tests are no longer available on the NHS for many people

The price varies from about £15-£50. However, some people are eligible for free tests. Visit www.nhsdirect.nhs.uk for more details. Note that free routine eye tests are available in Scotland

If you use a computer at work check whether your employer will pay for an eye test The tests vary from optician to opticianSome opticians may, but probably won't, include some of the extra tests listed in this article in their standard check

If you want further tests you'll probably have to pay. At the London City Eyes Clinic, all the above tests are included in a comprehensive eye screen, which costs £150. The Optomap scan costs an additional £45

Who's who? Optometrists (also known as ophthalmic opticians) are the opticians you are most likely to visit for sight tests and spectacles. They are trained to spot diseases that are revealed in the eye, such as diabetes

Dispensing Opticians are qualified to fit and supply spectacles to a prescription provided by an optometrist.

  25/10/2008. Times Online.