20/20 VISION Part I: Eyesight, perception and vision

In this first part of our three-part exploration of 20/20 vision, we are going to look at our physical eyes and how they work. Then we will explore perception and how the brain actually converts all that sensory information into images. Finally, we will look at some of the techniques for improving our vision naturally and ask if these really work.

20/20 vision is a term used to express normal visual acuity (the clarity or sharpness of vision) measured at a distance of 20 feet. ... If you have 20/100 vision, it means that you must be as close as 20 feet to see what a person with normal vision can see at 100 feet.

Having 20/20 vision does not necessarily mean you have perfect vision. 20/20 vision only indicates the sharpness or clarity of vision at a distance. Other important vision skills, including peripheral awareness or side vision, eye coordination, depth perception, focusing ability and colour vision, contribute to your overall visual ability.

Some people can see well at a distance but are unable to bring nearer objects into focus. This condition can be caused by hyperopia (far-sightedness) or presbyopia (loss of focusing ability). Others can see items that are close but cannot see those far away. This condition may be caused by myopia (near-sightedness).

Is it possible to see better than 20/20?

Yes, it's indeed possible to have sharper than 20/20 vision. In fact, most people with young,

healthy eyes are capable of identifying at least some of the letters on the 20/15 line or even smaller letters on the Snellen chart.

Most government agencies and health care institutions agree that legal blindness is defined as a visual acuity (central vision) of 20/200 or worse in the best seeing eye or a visual field (peripheral vision) that is limited to only 20 degrees.

There is no maximum prescription. Lenses can be made to compensate for just about any degree of myopia, astigmatism, or hyperopia so that your eye can see 20/20 with them on (provided they are healthy and you are too).

NWR 2020 Vision/A Tisdall Reg Charity: 295198 Page 1 Vision

Vision is a broader term than visual acuity or eyesight. In addition to clarity of sight or simply a description of the ability to see, the term "vision" includes all interactions between the eyes and the brain, and all neurological processes that take place in the brain to make the sense of vision possible.

Also, unlike simple eyesight or Snellen (high contrast) visual acuity, measures of vision include contrast sensitivity, the ability to track moving objects with smooth and accurate eye movements, colour vision, depth perception, focusing speed and accuracy, and more.

Because of the broader nature of the word “vision,” what is commonly called “20/20 vision" should really be called "20/20 visual acuity" or “20/20 eyesight.”

What is 20/20?

The term "20/20" and similar fractions (such as 20/60, 20/40 etc.) are visual acuity measurements. They also are called Snellen fractions, named after Herman Snellen, the Dutch ophthalmologist who developed this eyesight measurement system in 1862.

In the Snellen visual acuity system, the top number of the Snellen fraction is the viewing distance between the patient and the eye chart. In the United States, this distance typically is 20 feet; in the UK it is 6 metres (therefore 20/20 is equal to 6/6).

At this testing distance, the size of the letters on one of the smaller lines near the bottom of the eye chart has been standardised to correspond to "normal" visual acuity — this is the "20/20" line. If you can identify the letters on this line but none smaller, you have normal 20/20 visual acuity.

The increasingly larger letter sizes on the lines on the Snellen chart above the 20/20 line correspond to worse visual acuity measurements (20/25; 20/32; etc.); the lines with smaller letters below the 20/20 line on the chart correspond to visual acuity measurements that are even better than 20/20 vision (e.g. 20/16; 20/10).

The single big "E" at the top of most Snellen eye charts corresponds to 20/200 visual acuity. If this is the smallest letter size you can discern with your best corrective lenses in front of your eyes, you are considered legally blind.

NWR Theme: 2020 Vision/ A Tisdall Reg Charity: 295198 Page 2 There are over two million people in the UK living with sight loss. This includes around 350,000 people registered as blind or partially sighted who have severe and irreversible sight loss. It also includes those that have uncorrected refractive error or cataracts that may be reversed.

INTERESTING FACTS ABOUT EYES

• Your eyes are about 1 inch across and weigh about 0.25 of an ounce.

• The human eye can differentiate approximately 10 million different colours.

• Our eyes remain the same size throughout life, whereas our nose and ears never stop growing.

• The human eye blinks an average of 4,200,000 times a year. The purpose of blinking is to lubricate the eyes. Adults blink around 15 - 20 times a minute, which researchers say is more than the required amount to keep the eyes moist.

• Eyes are made up of over 2 million working parts.

• Each individual eye contains 107 million cells and all are light sensitive.

• Your eye is the fastest muscle in your body. Hence, the phrase: “In the blink of an eye.”

• The world’s most common eye colour is brown. However, brown eyes are blue eyes underneath. Consequently, a person can receive surgery in order to make their brown eyes blue. People with blue eyes share the same ancestor. Originally, all human beings had brown eyes, until a genetic mutation occurred between 6,000 and 10,000 years ago. Every single blue-eyed person shares this very distant relative.

• “Don’t It Make My Brown Eyes Blue” is a song recorded by American country music artist Crystal Gayle. The story goes that Richard Leigh wrote it while his dog, Amanda, sat at his feet, staring up at him with her big brown eyes. Strangely, a few years later, a rubbish collector threw rocks at the dog, hitting her in one of her eyes. Amanda developed cataracts, and one of her brown eyes literally turned blue.

• Some people are born with mismatched eye colours. This condition is known as heterochromia and is usually the result of a relative lack or excess of pigment in one eye. It is most often inherited but may also occur due to disease or injury.

• The cornea is the transparent covering of the iris and pupil. It protects your eyes from dirt and germs, as well as some of the sun’s UV rays. If your cornea becomes damaged you will experience distorted vision, because the light that enters your eye is interfered with.

NWR Theme: 2020 Vision/ A Tisdall Reg Charity: 295198 Page 3 • It’s a myth that liars make less eye contact. In fact, a well-practised liar will try to overcompensate as an attempt to “prove” they are telling the truth, by making too much eye contact and holding a gaze.

• Human corneas are very similar to a shark’s cornea. This similarity means that sharks’ eyes can be used as replacements in human eye surgeries.

• Anisocoria is a condition where a person’s pupils are not the same size. It can be present at birth or can be developed over time, however it is very rare. Sometimes, people with this condition will notice that the difference in size is only temporary, and they return to their normal sizes again.

David Bowie actually had this condition, making his eyes appear different colours when in fact they were the same. It happened after a school yard scrap when he was a teenager – although he never minded saying that it gave him added mystique.

• The “floaters” in your vision are permanent. They are mainly made up of protein strands floating inside the eye’s vitreous, casting shadows on the retina. Because the vitreous is completely stagnant, they will remain there indefinitely unless surgically removed.

• It’s impossible to sneeze with your eyes open. Your eyes and nose are connected by cranial nerves, so the stimulation from a sneeze travels up one nerve to the brain, then down another nerve to the eyelids, typically prompting a blink.

• Tears help protect our eyes from infection. Any dirt and dust that has managed to pass the defence of our eyelashes and brows is washed away by tears. They keep our eyes clean and moist and are filled with antibodies that fight infection.

• Our eyes close automatically to protect us from perceived dangers. The superb reflex control of our eyelids allows them close automatically when they detect that an object is too close to the eye or there is sudden bright light.

• We have two eyeballs for depth perception. Our eyes work together to help us judge the size and distance of objects, so that we can safely navigate around them. (The Stereoscope was a Victorian device that made use of this fact to create some of the first 3D images. Two photos were taken 3 inches apart and then set next to each other on a piece of card that was inserted into viewing binoculars perched on your nose – this meant that your eyes could suddenly see the image in 3D)

NWR Theme: 2020 Vision/ A Tisdall Reg Charity: 295198 Page 4 Viewing Rome through a Stereoscope

• Your eyes contain 7 million cones which help you see colour and detail, as well as 100 million cells called rods which help you see better in the dark. In order to work well, cones need more light than rods. Rods cannot perceive colour, just black, white and grey. However, they are very sensitive and tell us the shape of something.

• The human eye only sees three colours. The retina has three types of cones: one is sensitive to the colour red, one is sensitive to the colour blue and the other is sensitive to the colour green. These three cones work together to sense combinations of light waves that help us see millions of other colours and shades.

• There are colours that are too complex for the human eye to comprehend. These are known as “impossible colours”, which cannot be perceived due to being outside the strength of our three types of cone cell in the retina. However, some of these colours can be seen by mixing colour signals from the two eyes, or by looking at special “fatigue templates”.

• Red-green colour blindness is primarily found in men. The genes for the red and green colour receptors are found on the X chromosome, of which men only have one. Women, on the other hand, have two X chromosomes and the stronger of the two is superior. This means that even if one is faulty, a woman will still retain correct vision.

• Male and female brains process colours slightly differently. Research has shown that men and women see colours slightly differently. It is likely that the male hormone, testosterone, affects the way a male brain processes information taken in by the eye. However, the difference is only very small.

• Eye transplants are currently impossible due to the sensitivity of the optic nerve. Surgeons are currently unable to wire the optic nerve to the brain because it contains over 1 million nerve cells. This means a transplanted eye would not transmit signals to the brain and therefore fail to produce sight.

• Eye tests can detect Schizophrenia. The mental disorder can be diagnosed with 98.3% precision using a simple examination of the eyes. The test checks for abnormalities of eye movement.

NWR Theme: 2020 Vision/ A Tisdall Reg Charity: 295198 Page 5 • The cornea is the only tissue in the human body which doesn’t contain blood vessels. The cornea must remain clear in order to refract light correctly. If blood vessels were present, they would interfere with this process.

• In space, an astronaut cannot cry. Due to the lack of gravity in space, tears do not fall. Instead they collect in little balls and make a person’s eyes sting.

• Astigmatism refers to a curvature of the cornea or lens. It is a common and usually not a serious problem. It causes distorted vision and toric lenses are prescribed to aid the individual’s sight.

• Just behind our pupil is the lens - which is round, flat and thicker toward the middle. It is made of transparent, flexible tissue and, together with the cornea, helps to focus light onto the retina.

• Part of the retina is insensitive to light. Human eyes contain a small blind spot, known as the Punctum Caecum. It is rarely noticed, if ever, because our brains are able to use information from the other eye to fill in the vision gap.

• Diabetes affects the blood vessels of your eyes. If these blood vessels become blocked or leak then the retina, and perhaps your vision, will be harmed. This is called Diabetic Retinopathy and affects 40% of people who suffer from Type 1 diabetes and 20% of people who suffer from Type 2 diabetes.

• Diabetes is usually first detected during an eye test. Sufferers of type 2 diabetes often have no noticeable symptoms. If this is the case, then the condition is often first noticed during eye examinations due to tiny haemorrhages leaking from blood vessels at the back of the eye.

• Red eye in photos is caused by light from the flash bouncing off the capillaries in people’s eyes. When camera flash is used at night, or in dim lighting, it can reflect from the subject’s retina and show up on the picture as red eye. If the subject of the photo doesn’t look directly at the camera, there is less chance of red eye.

• Playing Tetris can treat a lazy eye. Canadian doctors have found that the puzzle game is effective in training both eyes to work together. In fact, it works better than the conventional eye patch.

• Your eyes start to develop just two weeks after conception. This is one of the reasons why it is so important for a pregnant woman to take care of her own body so that her unborn child can develop properly.

• At birth, babies can only see in black, white and some shades of grey. This is because certain nerve cells in their retina and brain are not fully developed. However, they develop the ability to see in colour as quickly as a week later.

• Ommetaphobia is the fear of eyes.

• Pirates wore earrings because they believed it improved their eyesight.

NWR Theme: 2020 Vision/ A Tisdall Reg Charity: 295198 Page 6 DO ANIMALS HAVE 20/20 VISION?

• The night vision of tigers is six times better than that of humans. Cats also have reflecting membranes behind their eyes which increases the amount of light entering the eye and enhances vision in low light conditions.

• In general birds have rather poor vision, apart from birds of prey. A recent study at Lund University in Sweden showed that Harris's hawk has the best colour vision out of all the animals investigated to date. Birds of prey, such as eagles and falcons, have some of the best eyes in the animal kingdom. Their eyes are forward-facing, which gives them excellent binocular vision.

IRIS RECOGNITION

While a fingerprint has 40 unique characteristics, an iris has 256. This is why retinal scans are increasingly being used for security purposes. A retinal scanner uses infrared light to map the unique pattern of blood vessels on a person’s retina. This pattern is so intricate that even identical twins do not have the same configuration.

In the film “Minority Report” based on a book by the Science Fiction Writer Philip K Dick, iris recognition is everywhere in society, so that when the hero John Anderson has to go on the run, he is forced to get an eye transplant to save him from capture. Gruesome stuff – but in real life, it is facial recognition technology that is being used very widely.

EYES AND YOUR HEALTH

Oily fish, vitamin A and vitamin C all help to preserve good eyesight. Studies have found that eating oily fish at least twice a week (such as salmon or mackerel), can help reduce the risk of age-related macular degeneration - a common cause of blindness in old age. Vitamin A and vitamin C also maintain good eye health.

NWR Theme: 2020 Vision/ A Tisdall Reg Charity: 295198 Page 7 Around 99% of the world’s population will first need reading glasses between the ages of 43 and 50. As we age, the lenses in our eyes slowly lose the ability to focus. This means that the vast majority of us will need some form of vision correction in our adult lives.

Flitting eyes suggest distress or tension. Sometimes, when a person’s eyes are darting around, it is because they are trying to find a solution or an answer in a difficult situation.

IS OUR EYESIGHT GETTING WORSE?

Well, yes – the short answer to that seems to be in the affirmative. Eyesight is getting worse with each generation. Currently about 60% of the world’s population wear glasses or contact lenses to correct vision. But why might this be?

An article in Psychology Today titled “Why do so many humans need glasses?” by Dr Jesse Marczyk Ph.D on 7th June 2017 attempted to answer this question. He referred to a paper Rose et al (2008) which reported on myopia in two samples of similarly aged Chinese children: 628 children living in Singapore and 124 living in Sydney. Of those living in Singapore, 29 percent appeared to display myopia, relative to only 3 percent of those living in Sydney. These dramatic differences in rates of myopia are all the stranger when you consider the rates of myopia in their parents were quite comparable. For the Sydney/Singapore samples, respectively, 32/29 percent of the children had no parent with myopia, 43/43 percent had one parent with myopia, and 25/28 percent had two parents with myopia. If myopia was simply the result of inherited genetic mutations, its frequencies between countries shouldn't be as different as they are, disqualifying hypotheses one and three from above.

When examining what behavioural correlates of myopia existed between countries, several were statistically—but not practically—significant, including number of books read and hours spent on computers or watching TV. The only appreciable behavioural difference between the two samples was the number of hours the children tended to spend outdoors. In Sydney, the children spent an average of about 14 hours a week outside, compared to a mere 3 hours in Singapore. It might be the case, then, that the human eye requires exposure to certain kinds of stimulation provided by outdoor activities to develop properly, and some novel aspects of modern culture (like spending lots of time indoors in a school when children are young) reduce such exposure (which might also explain the aforementioned IQ correlation: smarter children may be sent to school earlier). If that were true, we should expect that providing children with more time outdoors when they are young is preventative against myopia, which it actually seems to be.

NWR Theme: 2020 Vision/ A Tisdall Reg Charity: 295198 Page 8 LEARNING TO SEE

The information the eye receives from the outside world is actually upside down and our brain turns the image the correct way up. As a result of having a curved cornea, the light that enters our eyes is refracted and creates an upside-down image on the retina. When babies are born they see the world upside down for a month or more before their brain learns to correct this.

The eyesight of a new-born is about 20/400, according to paediatric ophthalmologist Dr Steven Levine in an article in CNN Health. This means that an object about 20 feet away would look as blurry to a new-born as an object about 400 feet away would look to an adult with normal eyesight. A baby's eyesight improves to 20/60 by about 6 months and then it might take until age 3 for a baby's vision to reach full development, according to Dr Levine.

Improving your eyesight naturally

Eye-care physician William Horatio Bates, M.D. (1860–1931) attributed nearly all sight problems to habitual strain of the eyes, and felt that glasses were harmful and never necessary. Bates self-published a book, Perfect Sight Without Glasses, as well as a magazine, Better Eyesight Magazine, detailing his approach to helping people relax such "strain", and thus, he claimed, improve their sight. His techniques centred on visualization and movement. He placed particular emphasis on imagining black letters and marks, and the movement of such. He also proposed that exposing the eyes to sunlight would help alleviate the "strain".

Despite continued and numerous anecdotal reports of successful results, including well- publicised support by Aldous Huxley, his approach has not been accepted by the medical establishment, possibly because what Bates’ method is really correcting is ‘perception’ rather than eyesight.

The Art of Seeing is a 1942 book by Aldous Huxley, which details his experience with and views on the Bates method, which according to Huxley improved his eyesight.

In the preface to the book, Huxley describes how, at the age of sixteen, he had a violent attack of keratitis punctata which made him nearly completely blind for eighteen months, and left him thereafter with severely impaired sight. He managed to live as a sighted person with the aid of strong spectacles, but reading, in particular, was a great strain.

NWR Theme: 2020 Vision/ A Tisdall Reg Charity: 295198 Page 9 In 1939 his ability to read became increasingly degraded, and he sought the help of Margaret Corbett, who was a teacher of the Bates method. He found this immensely helpful, and wrote “At the present time, my vision, though very far from normal, is about twice as good as it used to be when I wore spectacles, and before I had learned the art of seeing.”

According to Huxley, the prevailing medical view is that

“...the organs of vision are incapable of curing themselves … then the eyes must be totally different in kind from other parts of the body. Given favourable conditions, all other organs tend to free themselves from their defects. Not so the eyes. … it is a waste of time even to try to discover a treatment which will assist nature in its normal task of healing.”

He goes on to analyse the whole process of visual perception, using ideas and vocabulary taken from the philosopher C. D. Broad. He sums the analysis up as follows:

• Sensing is not the same as seeing.

• The eyes and the nervous system do the sensing, the mind does the perceiving.

• The faculty of perceiving is related to the individual’s accumulated experiences, in other words, to memory.

• Clear seeing is the product of accurate sensing and correct perceiving.

• Any improvement in the power of perceiving tends to be accompanied by an improvement in the power of sensing and of the product of sensing and perceiving which is seeing.

And while Bates' techniques have not been objectively shown to improve eyesight, certainly not for the reasons Bates gave himself, they have worked for a great number of people in practice, including an interesting Jewish American Meir Schneider.

Meir Schneider was born blind to deaf parents in 1954 because of congenital cataracts. After five unsuccessful surgeries on the lenses of his eyes, which left him with massive scar tissue, glaucoma, cataracts, cross-sightedness and nystagmus (involuntary rapid eye movement), his doctors pronounced his condition hopeless and he was certified permanently legally blind. He performed his reading and schoolwork in Braille. Inside, he never relinquished his dream of gaining sight.

Just months before his seventeenth birthday, Meir met a teenage boy who gave him hope that his dream of seeing could be realized. The boy taught him the Bates Method of eye exercises. Undeterred by the opposition and scepticism of family and physicians, Meir practised these exercises with extreme diligence – up to 13 hours per day. Using the Bates Method as his foundation, he developed many more eye exercises of his own and created his own regimen of self-massage and movement.

Today, he holds a current unrestricted California driver’s licence, and his vision continues to improve. From 20/2000 (able to see from one foot what a normally sighted person sees from

NWR Theme: 2020 Vision/ A Tisdall Reg Charity: 295198 Page 10 100 feet) to 20/60 (70% of normal vision)! According to his doctors however, he shouldn’t be able to see at all with the amount of damage he has to his lenses.

He found that the same principles which enabled him to gain functional eyesight could be applied to the entire body. His discoveries led to the creation of the Meir Schneider Method of Self-Healing through Bodywork and Movement, helping tens of thousands of people with serious physical and visual conditions worldwide.

An internationally respected therapist and educator, Meir is the founder and director of the School for Self-Healing in San Francisco, the author of The Natural Vision Improvement Kit, Movement for Self-Healing, Yoga for Your Eyes, Meir Schneider’s Miracle Eyesight Method, Self- Healing: My Life and Vision and the principal author of The Handbook of Self-Healing. He was awarded a PhD in the Healing Arts for his work with muscular dystrophy.

In 2007 Meir was honoured by Israel, named as one of the “Top Ten Most Inspirational Israelis” worldwide. In the fall of 2010 Meir Schneider was honoured by San Francisco Mayor Gavin Newsom with a ‘Certificate of Honour’ for his tireless efforts and a lifetime dedicated to improving the quality of life for individuals with both visual and physical limitations.

Trayner Glasses

Pinhole glasses are typically eyeglasses with lenses that are full of a grid of tiny holes. They help your eyes focus by shielding your vision from indirect rays of light. By letting less light into your eye, some people can see more clearly. Pinhole glasses are also called stenopeic glasses.

NWR Theme: 2020 Vision/ A Tisdall Reg Charity: 295198 Page 11 The "pinhole effect" has been known about for centuries and pinhole glasses are used by optometrists (who are qualified to examine vision) as a sight aid where conventional glasses cannot help - in the case of a scarred cornea, for example. But they are not normally used where prescription glasses can be used, because they cut down on light, and cannot give as clear an image.

The manufacturer, Trayner Pinhole Glasses, argues that its product has a more permanent effect than this. It says that while normal glasses encourage the eye to become lazy, the pinhole type encourage the ciliary muscles to become stronger, pulling the lens into the correct shape.

BELIEVING IS SEEING

It is an interesting but not well-known fact that people with Multiple Personality Disorder (MPD) can have significant variations in eyesight in each personality.

It seems that, as Aldous Huxley wrote, how we see the world has more to do with the structure of our brains and less to do with the biological structure of our eyes.

“We do not see the world as it is, but as we are”, or so it says in The Talmud, the ancient Jewish text. It seems that science is finally catching up with this ancient understanding. In a TED talk in 2017, a neuroscientist at the University of Sussex called Anil Seth, describes how our brains ‘hallucinate’ our conscious reality. “The eye simply sees patterns of light and it is the brain which gives meaning to these patterns. Right now, billions of neurons in your brain are working together to generate a conscious experience – your experience of the world around you and of yourself within it?” Our experience of the world, Anil says, is a ‘controlled hallucination’ and reality is simply a hallucination that we agree on. For example, take a look at these images (some of you may be familiar with them already) –

What do you see? Think about this before you look at the next page…

NWR Theme: 2020 Vision/ A Tisdall Reg Charity: 295198 Page 12 In the first one some see a rabbit, and some see a duck. Can you see both? In the second image there is both an old woman and a young one: which do you see? It is our brains that are interpreting the patterns in front of us and actually project what we know from the past onto our present experience.

The story goes that when Columbus sailed to the Americas, that the native Indians were unable to see his ships anchored off the shore. This was because they had no concept for ship. Their brains had not yet learned to see ships.

Part II will be on its way soon….

DISCLOSURE

MUCH OF THE INFORMATION ENCLOSED IN THIS PACK HAS BEEN RESOURCED FROM THE INTERNET AND WHILE EVERY EFFORT HAS BEEN MADE TO SUBSTANTIATE THESE FACTS, THERE MAY BE SOME ERRORS

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