Our eyes might be small, but they provide us with what many people consider to be the most important of our senses – vision.
How vision works
Vision occurs when light enters the eye through the pupil. With help from other important structures in the eye, like the iris and cornea, the appropriate amount of light is directed towards the lens.
Just like a lens in a camera sends a message to produce a film, the lens in the eye 'refracts' (bends) incoming light onto the retina. The retina is made up by millions of specialised cells known as rods and cones, which work together to transform the image into electrical energy, which is sent to the optic disk on the retina and transferred via electrical impulses along the optic nerve to be processed by the brain.
How the eye works
The eyes have been called the most complex organ in our body. It's amazing that something so small can have so many working parts. But when you consider how difficult the task of providing vision really is, perhaps it's no wonder after all.
Eye functions
- Seeing
When we see, we use our eyes and brain together. We see when light enters our eyes from objects we are looking at. Images we are looking at hit the retina at the back of our eyes upside down and back to front. They are then converted into electrical signals and sent to our brain through our optic nerve. From this, our brain can process what we see.
Vision is decreased if any of these parts of the eye are not working as they should.
- Crying
Tears begin in the lacrimal gland and with every blink the eyelids sweep them across the eye, spreading tears evenly across the surface. The blinking motion of eyelids forces the tears into tiny drains found at the inner corners of the upper and lower eyelids. The tears then travel through canals to something called the lacrimal sac which in turn drains into the nasal passage.
- Movement
There are six muscles which move the eyes up and down and left to right.
- Blinking
As we blink, tears wash our eyeballs, keeping them moist and clean. We blink about ten times a minute and over 10,000 times a year. The muscle that lets you blink is the fastest muscle in the body.
- Protecting
Our eye is well protected by our eyebrows, eyelashes and eye sockets. Our eyebrows keep sweat and rain out of our eyes. They are arched in shape to re-direct fluid to the sides of our eyes.
Eyelashes help to keep the dust and dirt out.
The eyes are set in part of the skull called the eye sockets. These help to protect your eyes from injury
Ten steps to healthy eyes
Eat right for good sight
Eating a healthy balanced diet can reduce your risk of developing common eye conditions. Eye friendly nutrients found in many fruits and vegetables including spinach, red peppers, kale, leeks, avocado, peaches and blueberries can help to protect against age-related macular degeneration (AMD) – a condition that impairs the vision of more than 600,000 people in the UK and is the leading cause of blindness in the western world.
Cold water fish such as sardines, mackerel and tuna are all excellent sources of DHA and Omega-3 fatty acids, which provide structural support to cell membranes in the eye and are recommended for dry eye, the treatment of macular degeneration and general sight preservation.
Recent research has shown how eating fish just once a week can reduce your risk of developing early AMD by up to 40 percent.
Exercise regularly
The eyes need oxygen to stay healthy and comfortable. Increasing scientific evidence suggests that aerobic exercise can increase crucial oxygen supplies to the optic nerve and lower pressure in the eye.
Reducing intraocular ‘eye’ pressure can help control conditions such as glaucoma and ocular hypertension. Aerobic exercise can also prevent the progression of diabetes, which in severe cases can lead to diabetic retinopathy.
To gain health benefits from exercise, the Department of Health recommends 30 minutes of exercise five days a week. Brisk walks, cycling and swimming are all excellent ways to reduce intraocular pressure.
Remember to consult your GP before starting any new exercise programme.
Get a good night's sleep
A good night’s sleep can help keep your eyes feeling bright and refreshed. Lack of sleep and fatigue can lead to your eyes becoming sore, irritated, puffy, red and bloodshot.
A quick fix for relieving your eyes from any discomfort caused by lack of sleep is to place a cold compress – wet tea bags, slices of cucumber or a cold wet facecloth – over your eyes then lie back and relax for ten minutes.
Don’t smoke
Smokers have a significantly higher risk of eye disease than non-smokers. According to research published by the RNIB, smokers are twice as likely to lose their sight in later life than non-smokers.
Tobacco chemicals damage the blood vessels behind your eyes and increase your risk of developing age-related macular degeneration (AMD).
However, the good news is that if you quit smoking your risk of developing AMD begins to decline.
Smoking is also associated with other eye diseases including cataracts.
Use goggles to protect your eyes
According to the British Safety Council, nearly a quarter of a million of us will injure our eyes annually, with almost 50 per cent of these injuries occurring as a result of accidents in the home.
Limit the amount of alcohol that you drink
Drinking too much alcohol interferes with your liver functions, reducing the levels of glutathione- an efficient antioxidant that can help protect against common eye disease.
The Department of Health advises that men should not drink more than three to four units of alcohol per day, and women should drink no more than two to three units of alcohol per day.
Protect your eyes against the damaging effects of UV light
Excessive exposure to the sun’s UV rays can lead to a sunburn-like condition called photokeratitis. This can be extremely painful and make your eyes red, swollen and watery. The symptoms of photokeratitis – an inflammation of the outer layer of the cornea, typically occurs after 6-12 hours of exposure and will normally clear up quickly, causing no permanent damage to the eye.
However, the damaging effects of ultraviolet (UV) develop over a long period and your risk of developing cataracts and other age-related conditions increases significantly.
By the age of 18, more than half a lifetime’s worth of UV light will have been absorbed by a child’s eyes- but it’s never too early to start protecting your eyes.
Ensure that your sunglasses filter AT LEAST 99 per cent of UVA and UVB light and look out for the CE or BS EN 1836:1997 marks when choosing your sunglasses.
Watch your weight and maintain a healthy BMI
Maintaining a healthy weight helps to preserve macular pigment density which, in turn, helps to protect the retina against the breakdown of cells and the onset of age-related macular degeneration (AMD).
Studies in the US have shown how people with higher body mass indexes tend to have low pigment density and therefore are at greater risk of AMD.
Damage to blood vessels in the eye caused by excess body weight have also been linked to the onset of glaucoma and diabetes.
Body mass index (BMI) is a measure of body fat based on height and weight that applies to both adult men and women.
To calculate your BMI yourself, follow these three steps:
1. Work out your height in metres and multiply the figure by itself
2. Measure your weight in kilograms
3. Divide your weight by your height squared (the answer to question 1)
So, if you are 1.5m tall and weigh 60kg, the calculation would be:
1.6 x 1.6 = 2.25.
BMI would be 60 divided by 2.25 = 26.66.
Check the results below to see where you fall under:
BMI results
You are considered underweight if your BMI is equal to or less than 18.5
You are considered normal weight if your BMI is between 18.5 and 24.9
You are considered overweight if your BMI is between 25 and 29.9
You are considered obese if your BMI is 30 or greater
Drink plenty of water
The human body is made up of 70 percent water. Water is essential for your body to work normally, and for keeping your eyes healthy. Dehydration can lead to dry, sore and irritated eyes. The Food Standards Agency recommends that you drink approximately 1.2 litres (6-8 glasses) of water every day and more when you exercise or if the weather is hot.
Have regular eye examinations
It is recommended that you have an eye examination once every two years, unless advised otherwise by your optometrist. An eye examination will not only detect problems with your vision but it can also uncover a number of other underlying health problems.
An eye examination really is an essential health check and helps to keep you and your eyes healthy.