1. The Eyes Perceive Things Upside Down
What we see are made up of light reflected from the objects and scenes we look at. However, because the cornea at the front of the eye is curved, it bends the light as it enters eye, meaning the image is upside down when it hits the retina at the back of the eye. When the brain interprets the image it turns it back the right way up so we see the world correctly.
In an experiment in the 1950s, Austrian Professor Theodor Erismann asked his assistant Ivo Kohler to wear a pair of goggles that made him see upside down. Fascinatingly, Kohler’s brain adapted and he began to see the world rightside-up through the goggles within about a week. The landmark study is still widely referenced today, such as in the work Sachse et al. on Visual perception in 2017.
2. Eyes are Filled with Jelly-Like substance
80% of the human eye is made of a firm jelly-like fluid called vitreous humour that is vital to eye health and function. This clear, colourless substance fills the space between the lens and the retina of your eye. Vitreous humour is 99% water, the rest is a mixture of collagen, proteins, salts and sugars. By filling the eye, vitreous humour is essential to maintaining the eye’s shape and keeping the fragile retina in the place.
3. There are Many Protective Features Around the Eye
Our skull and facial features have evolved over millions of years to protect the fragile eyeball. The socket itself is depressed into the skull, thereby protecting half the eye with bone. Eyebrows are there to catch sweat from the forehead and divert it away from the eyes. Eyelids close to shield the eye from light and particles when needed.
Eyelashes create a filter for dust and other particles but also act like the whiskers of a cat or mouse, by sensing when something is close to the eye and triggering the eyelid to close. The entire length of all the eyelashes shed by a human in their life is over 98 feet with each eyelash having a life span of about 5 months.
Despite these elements, the eye is still one of our most fragile organs, especially in the face of modern hazards like artificial light and industrial substances. Evolution has not caught up with these new hazards, so eye protection is crucial in these modern environments.
4. Eye Colour has Little or No Influence on Vision
It has been suggested that blue and green eyes are more sensitive to light than brown eyes, and that brown eyes are more susceptible to cataracts. Some studies even claim that people with brown eyes are better at responsive actions such as racquet sports, while people with lighter coloured eyes may be better at strategic thinking. Other studies dispute these theories.
After numerous studies, theories and old-wives-tales, the only thing that eye-colour researchers seem to agree on is that there is little or no difference between the seeing abilities of people with different eye colours. Experts also agree that everyone, regardless of eye colour, should use tinted glasses to protect their eyes from the sun.
5. Your Eyes Can Get Sunburned
Sunburn of the skin is now well understood but did you know you can also get sunburn of the eye. The condition is called photokeratitis and can cause pain, redness, blurriness, tearing, swelling and sensitivity to light. Just like how your skin can peel after sunburn, photokeratitis can lead to the corneal epithelium “sloughing off”. Effects can be felt long after exposure, so always wear good sunglasses when in the sun.
6. Are Carrots Actually Good For Your Eyes?
Many of us have been brought up being told that carrots are the best food for eyesight, even that eating carrots will help us see in the dark. While the beta-carotene rich vegetable is a healthy addition to your diet, it does not have specific benefits for the eyes aside from vitamin A, which is converted from beta-carotene in the body, but there are much better sources of vitamin A.
For eye health it is best to eat oily fish and green vegetables that contain lutein, zeaxanthin and meso-zeaxanthin, which support the eye’s protective mechanisms. Lutein and zeaxanthin occur naturally in foods like spinach, kale and other leafy greens, while meso-zeaxanthin can be found in certain fish.
7. Using Screens Causes Computer Vision Syndrome
Studies suggest that 50% to 90% of people who work at a computer screen show symptoms of computer vision syndrome (CVS). CVS is not one specific problem but a whole range of issues relating to eye strain and pain from too much exposure to screens.
Using a screen forces your eyes to focus and refocus all the time, the brightness and glare also make your eyes work harder, over time this repetitive strain can take a toll on your eye muscles.
