Seeing squiggles. Flashing lights. The eye danger signs you can't afford to ignore

We tend to think that if it doesn't hurt, it must be fine - but ignoring odd eye symptoms is a mistake.

'There are no pain receptors in the eye, so if you're seeing things, but feel no pain it doesn't mean you're OK,' says Dr Susan Blakeney of the College of Optometrists.

MATTHEW BARBOUR reveals what those ocular changes really mean and when it's time to worry.

Boy wearing silly glasses with eyeballs

Save your sight: Know the warning signs of a problem so you can act before it's too late


SYMPTOM: Tiny dark shadows floating across the eyes.

CAUSE: Floaters are a normal part of everyone's vision and usually nothing to worry about, says Dr Blakeney.

'What you're actually seeing are shadows cast by rogue strands of collagen. These form part of the vitreous jelly which maintain the eye's shape, but they can pull free from the edge of the jelly and float harmlessly across the field of vision.

'It's still not known why this happens, though the problem is more common with age, as the jelly liquefies over time.' While the vast majority of us have just one or two floaters at any one time, others can have hundreds permanently drifting past.

TREATMENT: Floaters are harmless, but if they start to have a real impact on sight, they can be rectified with a vitrectomy. Normally performed under a general anaesthetic, this replaces the vitrous jelly with saline solution. Healthy jelly then grows back.

WHEN TO WORRY: If the occasional floater turns into a sudden 'cobweb' of squiggles, especially with associated flashes, or one single, large floater that won't disappear.

'This is a sign of vitreous detachment, where the vitreous jelly pulls away from the retina,' says Dr Blakeney. 'As the gel pulls away it can tear or detach the retina - the light-sensitive tissue at the back of the eye - cutting off its blood supply so it can no longer send images to the brain.'

Vitreous jelly can get behind the retina and, like wallpaper, the retina can peel off. If the rip is at the top, with gravity, the retina can be pulled off in less than 24 hours; with a rip at the bottom, that process can take weeks.

'The main symptom of detachment is a large blank area in your vision that won't go away, which may be associated with flashing lights or a general fuzziness.

'If this happens, go to A&E straight away as it can lead to permanent blindness - but if caught early enough, a torn or detached retina can be put back into place.'

Retinal detachment is more common in short-sighted people, as the retina is stretched anyway, or after an eye operation or head trauma, such as a road accident.


Kaleidoscope vision: This could be a warning of a migraine

Kaleidoscope vision: This could be a warning of a migraine

SYMPTOM: Like looking through a kaleidoscope with zig-zaggy lines.

CAUSE: All of us will see coloured spots if we stare at a bright object for long enough and then at a white wall. This is caused when the photosensitive cells on the retina are temporarily bleached and take a few seconds to adapt.

Your brain interprets this as different colours, says Neil Constantine-Smith, Specsavers optician. Flashing lights can also be an early warning for migraines.

'Flashing lights that last for 15 to 30 minutes are often symptomatic of ocular migraines, which are headaches that also cause coloured lights usually in both eyes,' he says.

'These flashing lights look like cracked glass or water running down over sparkling lights.'

TREATMENT: 'Once the flashing lights start you can prevent a fullblown migraine by taking painkillers, drinking water, upping your blood sugar with food and laying down in a quiet, dark room,' says Mr Constantine-Smith.

WHEN TO WORRY: 'If you stare at a n very bright light, such as the sun or a welding torch, for long enough, those images can burn into your retina, damaging your long- term sight , ' says Mr Constantine-Smith.

If the multi-coloured lights last for longer than 30 minutes, it could signify a detached retina.

'Unlike ocular migraines, these are almost always in one eye, so put a hand over one eye and see if it's the same on both sides,' he says. 'If it lasts for more than 30 minutes and affects only one eye, head to A&E - you may need surgery to re-attach the retina.'


SYMPTOM: Misty, blurred vision, as if you're looking through ultrathin tracing paper.

CAUSE: Fogginess is most commonly a symptom of shortsightedness, says David Berghardt, clinical optometrist in Nettleham, Lincolnshire. However, it can also be caused by dry eye syndrome, which affects two million Britons.

This is where you don't produce enough tears or the tear film evaporates too quickly, causing the eyes to dry out and become inflamed. This can lead to a deterioration of vision.

'With no moisture on your cornea, it can feel as if you're dragging your eyelids over ground glass,' he says. 'Dry eye syndrome is increasingly common thanks to the increasing use of air conditioning and computer screens.'

TREATMENT: Dry eyes can be alleviated with eye drops from your local pharmacy.

WHEN TO WORRY: If an eye test rules out short-sightedness and the fogginess has appeared suddenly and isn't eased by eye drops, the problem could be related to blood circulation. A blood vessel blockage at the back of the eye can cause fogginess.

It may be accompanied by loss of the top part of your vision, so you wouldn't be able to see objects in front and above you without tilting your head.

In effect, this is a 'mini-stroke' in your eye, says Mr Berghardt. 'This generally happens in people over 50. Head to your GP straight away - a full-blown stroke could be on the way,' he says.

A persistent fogginess is more likely to be a cataract, which is when the lens of the eye becomes cloudy - again this is more commonly seen in those over 50.

'Cataracts are common, but often are not detected for months until your unaffected eye is shut - as you might do when you get a piece of grit in it. You then discover you have been compensating by using the other eye more,' he says.

In rare cases, fogginess can be caused by a brain tumour pressing against the back of the eye, or optic neuritis - inflammation of the optic nerve. The symptoms include washed-out colours and loss of contrast.

'This can be a symptom of multiple sclerosis, but is rare, so speak to a specialist before panicking,' says Mr Berghardt.


Seeing things: Hallucinations should not be dismissed as they could be a sign you're losing your vision

Seeing things: Hallucinations should not be dismissed as they could be a sign you're losing your vision

SYMPTOM: Seeing people and objects that are not there.

CAUSE: When we look at something, the information from the eyes stops the brain creating its own pictures, says Brendan Moriarty, a consultant eye surgeon in Altrincham, Cheshire.

But when people start losing their sight - most commonly due to age- related macular degeneration or sometimes glaucoma - their brains don't receive as many pictures and new fantasy pictures or old pictures stored in our brains are released and experienced as real objects.

'It's a condition known as Charles Bonnet Syndrome (CBS), named after the Swiss philosopher who noticed his blind grandfather having hallucinations of things that obviously weren't there,' says Mr Moriarty.

With more than 100,000 diagnosed sufferers in Britain alone, CBS can affect anyone at any age with diminishing eyesight.

'Even people with normal vision can develop it if they are blindfolded,' he says. 'The brain starts to build artificial images from the areas we use every day to process faces, objects, landscapes and colours.'

TREATMENT: There is no treatment of proven effectiveness for CBS. It usually disappears within 18 months, as experience teaches the brain the hallucinations aren't real.

However, some people experience CBS for just a few days and others many years, and the hallucinations can last only a few seconds or continue for most of the day.

For those experiencing CBS, knowing they are suffering from this syndrome and not a mental illness seems to be the best treatment, as it helps them cope with the hallucinations. Interrupting the hallucination for a short time by closing the eyes or blinking is sometimes helpful.

WHEN TO WORRY: 'The biggest problem with CBS is that elderly people don't tell you they're seeing strange things, such as spiders crawling up the wall, as they don't want to appear mad,' says Mr Moriarty.

'But it's vital they tell someone as with proper diagnosis they can get on with their lives, knowing what causes their hallucinations.'


SYMPTOM: This makes you feel as if you' re looking down a toi let roll tube.

CAUSE: 'While the normal field of vision is 120 degrees up and down, and 150 from left to right, with tunnel vision those figures are slashed to less than ten,' says Dr Blakeney.

'It's a slow change that can creep in over years, as you gradually lose your peripheral vision.'

A largely hereditary condition often brought on by poor diet, obesity and smoking, in tunnel vision the 'rod' cells around the edge of the eyes, which capture dim light, degenerate and die.

'Often the first thing people notice is bumping into door frames, by which time it can be too late. 'So be sure to have regular eye tests - every two years for the over-40s,' says Dr Blakeney.

TREATMENT: Medicated eye drops.

WHEN TO WORRY: Tunnel vision can also be caused by glaucoma. This is where the eye produces too much fluid or does not drain enough away, increasing pressure in the eyeball, which can damage the optic nerve and cause tunnel vision, among other symptoms.

'The damage caused by glaucoma can't be reversed, but if caught early, it can be stopped by medicated eye drops - eye tests are essential,' says Dr Blakeney.

If you're losing night vision and also experiencing tunnel vision, it could be caused by retinitis pigmentosa (RP), a group of genetic eye diseases that cause progressive loss of vision and affect 25,000 people in Britain.

'Unfortunately, there's nothing you can do about it,' says Dr Blakeney.

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