There are more myths about the human eye than perhaps any other part of the body.
Here are some of the old chestnuts and what the experts say:
If you keep crossing your eyes, you will be cross-eyed permanently.
Reading by torchlight under the bed covers will ruin your eyes.
False – But the strain may give you a headache.
If you watch television and read a lot, you’ll need spectacles earlier.
False – They are harmless activities.
Sitting close to the TV screen will harm your eyes.
False – Though it could cause headaches. But you should check for short sightedness.
Strong sunlight will harm your eyes. There is little evidence for this, though looking directly at the sun can burn the retina and lead to blindness. Sunglasses are good because they screen out ultraviolet light, too much of which can affect the eyelids and skin around the eyes and may cause cancer.
Our vision is more complex than any camera and adapts to almost any condition without damage. Some authorities claim there is no conclusive proof that fluorescent lighting or visual display terminal screens have an adverse effect. (The amount of radiation, they say is about the same as that from a television screen).
Why is it some people need glasses before others?
“There is usually family history of short-sightedness or long-sightedness” explained the senior ophthalmology registrar at one of Sydney’s teaching hospitals. Diseases such as diabetes can also play a part in poor vision. So can injuries. An injury causing a cataract for instance may mean that the person has to wear glasses until the cataract is removed. Children may be born with cataracts.
Healthy people with good vision can do little to improve their sight, the doctor said, quoting some of the misconceptions about eye care.
Eye exercises – These are once used by people with squints or “lazy eye”, but most have little or no effect.
Eye baths – A routine eye wash should be done if an eye doctor recommends that you do so.
Vitamins – Eating lots of carrots (containing vitamin A) does not mean you will see better in the dark, but an adequate vitamin intake, particularly of A, is necessary, and should come from a normal, healthy diet. In underdeveloped countries, malnutrition and lack of vitamin A, and the protein to which it is bound, can cause eye disease. Night vision is affected, then day vision. Eye ulcers can occur.
Trachoma (or chlamydia trachomatis) derives from an organism which is between a bacterium and a virus. The disease has gradually become endemic to the Aboriginal community.
Eye drops – Only use those prescribed by your general practitioner or eye specialist. Discard after the recommended date. Used too frequently, eye drops become less effective. Routine eye drops don’t improve eye health. But, if you have bloodshot eyes, some can make you look more attractive by shrinking the blood vessels in the white of the eye. Eye redness is usually a reaction to dust, smog, wind, glare, lack of sleep. Prevention is the best treatment.
Eye glasses – These do no more than simply make you see better, by correcting visual errors and helping you to focus. Children who squint are helped by the right glasses. Although in their teens some people are a little short-sighted, by middle age they may not need reading glasses as early as the long-sighted. Some people with cataracts may be able to discard their reading glasses because a cataract makes them short-sighted. They can then read more comfortably, although they can’t see at a distance. The elderly often describe it by saying: “I have got my second sight.”
Contact lenses – These can correct visual errors, but not permanently correct nearsightedness. You have to keep wearing them. Some contact lenses, if fitted incorrectly, can change the shape of your eye. You then have to leave them out for a long period until the eye goes back to its usual shape. Caring for contact lenses requires a combination of cleaning, disinfecting, soaking and wetting, rinsing and storing.
Check ups – Children should be screened immediately when a parent notices a problem such as one eye turning in, an eye that wanders, not seeing normally, or if there is a family history of squint or the other children wear glasses. If an eye or eyelid looks inflamed, is painful or injured, seek medical help. It is never too early to have a child seen by an ophthalmologist. If there is a history of congenital cataract, have the baby’s eye examined as soon as possible.
Routine eye examinations are done at infants school and periodically throughout school life. Checks should be done, if you notice pain, infection or visual problems.
Diabetics under the under of 15 should have an examination followed by a check every five years. After 15, routine checks should be done every two years or yearly if there is a change in vision. Diabetes can affect blood vessels in the eye. The vessels become leaky and the macula water-logged. Sometimes a laser beam is used to seal them. Diabetics may also develop abnormal new blood vessels which bleed easily, causing vitreous haemorrhage (bleeding within the jelly inside the eye). Repeated haemorrhage can destroy the eyes. Laser treatment can prevent this.
From the age of 40 everyone should have routine eye checks every 2 to 3 years – more frequently if there is a family history of glaucoma or cataracts. Don’t wait until your vision is poor. Glaucoma sufferers may think their vision is fine, but, their eyesight is deteriorating.
The ophthalmologist (eye doctor) checks the vision of young children who can’t read the eye chart, using symbols, pictures, and little games. Eye drops are then used to dilate the pupils and help with refraction (trying various lenses to see which gives the best vision) before prescribing glasses if necessary. The doctor also looks for squint (tendency for the eye to turn) and examines the back of the eyes for signs of disease.
Adults read lines of letters which become smaller on an eye to test vision. The doctor will do a refraction before prescribing glasses. He also examines the front part of the eye microscopically, looking for possible disease.
Next the check up for glaucoma, a prolonged build-up of pressure that can damage the optic nerve. which is essential for sight. First, he puts in eye drops which contain a dye and a local anaesthetic then he checks the pressure within the eye using an application Tonometer. This painless test is very important because untreated glaucoma can lead to blindness. Once diagnosed, there are now excellent drugs which keep the pressure down and prevent damage.
Place the Amsler’s grid at a comfortable reading distance where light is consistent and without glare.
Test each eye separately. Covering one eye at a time and focusing on the dot.
It you notice any wavy lines. gaps or black spots you should arrange to see your eye care professional immediately.
If you accidentally splash a poison in your eye , irrigate with tap water (put your head under the tap) for 15 to 20 minutes – then seek medical help.
Alkaline chemicals present in many household products are worse than acids. Acids will cause the protein in the cornea to coagulate, preventing any more penetration by the chemical but alkaline can burn through the cornea.
Don’t remove foreign bodies other than by gentle irrigation. If this does not work seek medical attention.
Eye injuries in sport are common. A squash bad is small enough to fit inside the eye’s orbital socket. If you play squash, wear safety glasses specially designed to wrap around the eyes. If you are hit by a ball or racquet go immediately to a hospital casualty department, or a doctor.
Most viruses cause low-grade irritation, a clear sticky exudate and red eyes for several weeks until the body’s defences overcome the infection. Soothing drops and ointment may be used, but time is the primary healer.
Contact your eye doctor if any of these symptoms occur:
- blurred vision
- loss of side vision
- double vision
- a veil across your vision
- pain in the eye
- vision going black in one eye
- reddened eye
- flashes or streaks of light
- bulging of one or both eyes
- crusting or excessive tearing
- crossed, turned or wandering eyes
- change in floaters (spot, strings or shadows)
- twitching eyes
Sudden loss of vision may indicate a lack of blood supply to the eye (like a stroke in the eye) and needs urgent attention. Distortion of vision: if a straight line seems to have a kink, seek treatment urgently. This may indicate degeneration of the macula. In some cases it can be treated with a laser beam.