There are loads of myths relating to eyes and eyesight, these five are the most commonly encountered in the consulting room.
Eating carrots is good for your eyes
This is for the most part true. Carrots contain Carotenoid Pigments that are beneficial in reducing the risk of certain cancers and eye disease such as Macular Degeneration. One particular carotenoid, Beta-Carotene, is converted to Vitamin A. While this is a requirement for good eye health, it’s important to know that it is a fat soluble vitamin and can be toxic in high doses. Fortunately eating large quantities of carrots is unlikely to give you a Vitamin A overdose because Beta-Carotene is not converted rapidly enough to toxic levels. In any event, consuming large amounts is also not likely to be any more beneficial than a balanced healthy diet. It’s good to know that Carotenoids can also be found in many other intensely coloured fruits and vegetables, which are therefore also good for your eyes.
Wearing glasses will weaken or damage your eyes
There is some debate amongst academics and clinicians about how strong to make a pair of glasses for a young child going through their developmental period, however, for the general population this myth is incorrect. Glasses or contact lenses correct refractive errors (this means that glasses will bend the light entering the eye so that it falls in sharp focus on the sensitive retina). Just like the film in an old camera, a poorly focused image will result in a blurry photo. Similarly, a sharply focused image on the retina will be perceived as clear by your brain (providing there is no eye disease present). Choosing not to wear glasses will simply just render your world blurry and will have no other effect. So, wearing your glasses, not wearing your glasses, or wearing someone else’s glasses (however this option might give you a headache), will not ruin your eye health or sight.
Staring at the sun can damage your eye sight
This is absolutely true, and we have personally seen in our clinics permanent damage sustained to the retina from Solar Eclipse viewing. The sun’s radiation intensity varies throughout the day, so the amount of time required to damage the retina will also vary, but guessing how long that might be is fraught with danger. There is also a common belief that viewing the sun with sunglasses or filters is safe, however this is also a myth, as filters cause the pupils to dilate, allowing even more of the sun’s harmful radiation to enter the eye. Most sunglasses are not designed to filter out harmful radiant wavelengths responsible for this type of damage, thus providing nothing more than a false sense of security. When purchasing sunglasses always look for the Australian Standards sticker stating the level of UV protection. There are several levels of protection offered and this will be indicated on the sticker or tag. This is your assurance that the sunglasses are compliant with the laws and will protect you from the sun’s harmful rays, in the conditions that you wish to wear them.
Sitting too close to the TV and computer screen damages your eyes
There is little truth to this, however staring at screens can cause symptoms of eye strain and discomfort that diminish with ceasing of the activity. The causes of these symptoms include excessive prolonged focusing, inappropriate screen brightness and contrast, and eye dryness due to staring with a reduced blink frequency. There is also no evidence to support the theory that radiation emitted from screens, including light from the blue spectrum, is at a high enough intensity to cause any form of eye damage.
Crossing your eyes can cause them to be permanently cross-eyed
The causes of permanently “turned” eyes are many and include uncorrected refractive errors (particularly “long-sightedness”), disease (eg. Thyroid condition), head trauma causing damage to the cranial nerves, and brain compression from an aneurysm or tumour. In a normal healthy person, the extra-ocular muscles function normally and allow for a variety of eye gaze positions, including extreme convergence (going “cross-eyed”), that are completely reversible. These muscles do not spasm into a permanent position, and are commanded back into position by the cranial nerves that communicate to them. If you have any worries about your eye health then consult with your optometrist.