Eyesight myths: True or false

THERE is a host of old wives' tales and dire warnings about our eyes. Here, Robert MacLaren, a professor of ophthalmology, sorts fact from fiction.

Carrots are high in vitamin A which is necessary for good vision but a balanced diet will be enough Carrots are high in vitamin A which is necessary for good vision but a balanced diet will be enough

OLD adages such as “reading in dim light will ruin your eyes” or that munching on carrots will help you see in the dark have been around for generations but are they true? They are repeated so often it can be difficult to distinguish the myths from advice that stands up to scientific scrutiny.

Here, Professor MacLaren, from Oxford University takes a look at some of the most popular beliefs about our peepers and assesses whether they should be heeded or taken with a pinch of salt.

Sitting too close to the TV or staring at a computer screen will ruin your eyesight


Sitting too close to a TV or staring at a computer screen for too long will hurt your eyes but only temporarily. Those who stare at screens for long periods tend not to blink which makes the eyes dry and means vision suffers.

If you are looking at something up close it’s a good idea to take breaks and look into the distance.

Eyes are not designed to spend all day looking at a computer screen but it’s not going to cause any long-term damage.

Squinting damages your sight


Squinting is an attempt to make the pupil smaller so that it lets in less light. Closing your eyelids together enhances focus so squinting can temporarily help someone who needs glasses to see better. It might also indicate you have a refractive error where the eye cannot focus light correctly, resulting in blurry vision such as near or farsightedness.

Squinting won’t permanently damage vision but it can give you a headache because it involves contraction of the facial muscles.

Reading small print or sewing in dim light damages your vision


Reading in poor light can cause eye fatigue but it won’t damage your eyes. Good lighting will make reading easier and prevent fatigue especially for older people whose lenses no longer change shape as easily as they once did.

In low light the pupil is enlarged so whatever defects there are in the lens are not corrected. When it is bright you have a much greater depth of focus so more outside light can help you see better.

The retina is not damaged by the high amount of light that is let in by an expanded pupil in the dark. Having to focus on a smaller area is likely to strain the eyes but will not cause lasting damage.

You’ll have the same eye problems as your parents


Many eye problems are genetic but inheriting them is not guaranteed.

Some such as glaucoma and macular degeneration are more likely to be inherited but not always. Most occur without family history.

Being near or farsighted seems to be related to whether a parent had the problem. However, many vision problems have little to do with genetics.

Cataracts are cloudy patches that develop in the lens. Initially they can make your vision blurry but if they progress they can lead to very poor vision and blindness. Caused by ageing, it happens to everybody eventually.

Your vision will deteriorate as you get older


Some age problems are inevitable. The retina is the light-sensitive film at the back of the eye (similar to the film of a camera). It is made up of neurons which in a similar way to other parts of the brain degenerate slowly throughout life.

Young adults have about six million cone cells in each eye which are similar to the coloured pixels of a screen. This drops steadily throughout life and the lining of the back of the eye becomes uneven. Pixel resolution and image quality also declines.

Age-related cataracts however can be treated by surgery. A new plastic lens with high-quality optics is used to replace the old and clouded human lens.

Eating carrots will improve your eyesight


Diet is important for good vision but that doesn’t mean eating carrots all day will give you eagle eyes. The belief that carrots can help eyesight dates back to the Second World War when the Royal Air Force was trying to hide the fact it had developed a sophisticated radar system to shoot down German bombers.

The RAF claimed the accuracy of its fighter pilots at night was a result of them being fed carrots. Having said that, carrots are high in vitamin A which is necessary for good vision. However a balanced diet will provide enough.

Dark green vegetables such as spinach and broccoli contain lutein which can help prevent retina damage. Also found in egg yolk, this nutrient can protect the macula and may help prevent macular degeneration, a condition in older adults where vision is lost in the centre of the eye.

Eye exercises can help you see better


Unfortunately, there is little eye exercises can do to improve your vision. They can be used by children to help with a condition called convergence insufficiency in which the eyes cannot focus on close objects easily.

For adults, focusing difficulties and convergence can be improved with eye exercises although this does take a lot of time and effort. Eye exercises promoted as helping people get rid of glasses, known as the Bates method, have no scientific backing.

As we age our vision naturally deteriorates and exercises will not reverse that. However, exercises may help you learn to use the vision you have more effectively.

Someone with macular degeneration may be helped if they practise looking through other parts of the eye.

Using glasses for a long period will cause vision to deteriorate, leading to a dependence on corrective lenses


This notion assumes that wearing the correct glasses somehow changes the physiology of your eye. It doesn’t.

With age our eyes deteriorate and someone who needed reading glasses at 40 is likely to need a stronger pair at 50 whether they have been using their glasses or not. The out-of-focus world that develops over time is due to the growing of the lens of the eye which is the only part of the eye that keeps growing significantly and a process that prevents the eye from working as well as it did.

Not wearing your glasses will cause sight to deteriorate faster


Trying to focus without glasses may strain your eyes but it will not cause lasting damage although excessive squinting is likely to give you a headache.

By wearing glasses your vision doesn’t get worse more quickly and by not wearing them you are doing your vision a disservice.

It is fine to look at the sun or other bright objects as long as you squint


Looking directly at the sun for less than a minute with the naked eye can blind you even during a lunar eclipse.

Even if you squint the ultraviolet rays can still damage the cornea, lens and retina.

Experts agree that it’s best to avoid looking directly at the sun and to wear protective glasses around very bright objects.