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Visual Impairment in Adults

Visual Impairment in Adults

In 2001, an estimated 81,500 New Zealand adults were blind or partially sighted.  Almost 10% of these were completely blind.  Although some visual impairment is present from birth, most blind and partially-sighted people lose their sight later in life.  Sometimes vision loss is caused through accidents. According to the World Health Organisation 75% of blindness in the world could have been prevented.

Common causes:

Failing near vision (presbyopia)
The ability of the lens to focus gradually decreases with age, hence many people over 40 need reading glasses. This is a natural part of ageing, and the use of glasses does not slow down this process.

Age-related Macular Degeneration
The leading cause of blindness, especially in the over 60's.  Cells in the macula (part of the retina responsible for clear, sharp vision) degenerate. Vision lost cannot be restored. Smoking and prolonged exposure to bright sunlight are risk factors, and it can be hereditary. It is usually slowly progressive, and is not treatable.

Cataracts are the most common cause of vision loss. They result from chemical changes in the lens of the eye, causing the clear lens to turn cloudy. Sufferers often notice blurring or haziness of vision, and increased sensitivity to glare. Risk factors are age, family history, injury or disease. Not all will be severe enough to warrant surgery, and the visual impairment can often be corrected with glasses or contact lenses. If surgery is required, it is usually highly effective at restoring lost sight.

10% of people over 70 will have glaucoma. High pressures inside the eye gradually damage the retina, leading to loss of vision. Sufferers may notice "tunnel" vision, blurred vision or coloured halos around lights - however it often progresses silently and most people are unaware until it is in an advanced state. It runs in families, and the onset is most common in the over-50's. It is preventable if picked up early. If not detected, it can lead to permanent blindness. Treatment once detected is with eye drops that reduce the pressure inside the eye and prevent further damage.

Diabetes related retinopathy
Over 200,000 people in NZ suffer from diabetes, and one of the biggest risks is blindness and loss of vision. Diabetes, especially when poorly controlled, damages the tiny blood vessels at the back of the eye. These can leak into the eye, causing permanent loss of vision. Diabetics may notice rapid changes in vision, sensitivity to glare and reduced night vision. Diabetics who keep their blood sugars tightly controlled, and enrol in the free annual screening programme, are less likely to develop diabetes related retinopathy. Regular eye checks mean that any damage that is occurring can be picked up and treated promptly (often with laser therapy), reducing the risk of permanent visual loss.

Eye injuries
Around 20,000 New Zealanders suffer eye injuries each year, most commonly in the house and garden. 90% of these are preventable by using safety goggles or glasses. Many of these injuries will lead to permanent visual loss or blindness. Common causes are nail or metal fragments from hammers, chisels or saws; chemical burns; spike injuries from twigs, plants, pliers or screwdrivers; firework injuries.

Danger signs
The following symptoms may indicate serious underlying eye disease. If you experience any of them, make an urgent appointment to see your optometrist or GP.

- Sudden loss or change in vision;
- Floaters - sudden appearance of floaters, or a substantial floater that you haven't noticed before;
- Shadow or curtain encroaching on your vision - this may indicate damage to the retina and delay could lead to permanent visual loss;
- Flashing lights - especially in the periphery or outside of your vision.  

How can we protect our sight?

- Protect your eyes from damaging UV light. This will reduce the risk of developing ARMD, cataracts and cancer
- Wear wrap-around style sunglasses that are 100% UV light protective.
- Monitor your blood pressure. High blood pressure affects the blood vessels in the eye, and can lead to visual loss.
- Get a diabetes test.
- Get your eyes checked by an optometrist at least every two years. The majority of eye conditions that can lead to blindness develop slowly. The earlier an eye disease is picked up, the more vision can be saved.
- If you're working on a computer take a mini break every 20 minutes, blink rapidly and look into the distance.
- Move your computer screen: it should be at an arm's length away. The screen should stand straight in front of the face. The centre of the monitor should be about 10cm lower than your eyes.
- Invest in a pair of safety glasses and make sure you wear them while gardening, using a hammer or power tool, working with chemicals or lighting fireworks.

Where to go for more information:

The Royal New Zealand Foundation for the Blind 
The New Zealand Association of Optometrists
Great website for information of visual impairment and eye care.