Dear Readers,

Joanne, a middle-age woman who resides off Waltham Park Road, St Andrew, recently turned 58 and is worried about her vision. She has been driving for more than 25 years and, during this year, she has noticed real problems with driving at night.

Joanne even had her vision tested and is now wearing tested glasses for short-sightedness but she has experienced only marginal improvement and her night-vision problems are still affecting her.

Joanne is frustrated because she now tries to get home before dark, limiting her evening activities! She has experienced a few near misses at night, particularly on one occasion when she misjudged car.

She experiences no problems during the day. Joanne asked Lifeline, "what's going on and what can I do to remedy the problem?"

Night-time driving is very different from driving during the daylight hours. without the colour and contrasts provided during the day, vision and depth perception can be significantly impaired. About 90 per cent of reaction ability of any driver behind a steering wheel relies on sight. with nightfall comes diminishing ability to see, with a decrease in colour recognition, depth perception and peripheral vision. Also, most drivers tend to be less alert at night (after a hard day's work). Statistics show that night driving has a fatality rate (per mile), triple that of daytime driving!

There are four main categories of night-vision impairment or night blindness.

1) Blurred vision in dim light, with sharp-to-moderately-acceptable vision in bright light. This type of night-vision defect affects most people with night-vision disability.

2) Blinding glares, or halos around lights, which disrupt night vision and temporarily blind the driver, although vision is sharp in dim light where there is no focused light to cause a glare. Drivers in this group are not often otherwise handicapped, but a light glare can cause a fatal accident.

3) Insufficient perception of even dim light. This problem is often referred to as 'night blindness' which means below-average ability to see at night or in low light.

4) Combinations of two or more of categories, 1-3, can lead to a severe visual disability at night.

The large majority of individuals with night-vision disability are healthy people, having only limited visual problems at night-time, when driving, and feel uncomfortable driving at night.

Most of these individuals can be helped with special prescription glasses prescribed for night driving. People most affected are the 45-55-year-olds, who are starting to become Presbyopic (unable to see objects close), due to the ageing process.

The problem with blurred night vision may affect only one or both eyes. Most people can correct this problem by obtaining corrective lenses. At times, corrective lenses don't seem to work. This can occur because the eyes were tested in bright light rather than in dim light. The recommendation for this group of individuals is to visit an ophthalmologist for a complete examination of both eyes, and not just have the eyes tested for a prescription for glasses (lenses), which is sometimes the case.

In individuals with night-vision problems, dim-light testing of the eyes should be performed. Usually, lenses prescribed for night-time visual problems will also work well in the daytime, but the reverse is not true. Lenses prescribed using bright-light testing will work for the day, but not necessarily at night.

When blinding glares and halos are seen at night, usually some eye disorder is present in one or both eyes. The person may be developing eye cataracts or have some other internal eye problem which needs an eye specialist's attention. Correcting the underlying eye problem can help significantly to reduce the glares and halos experienced with driving at night.

Night blindness (poor perception of dim light) has several causes such as glaucoma or even a vitamin deficiency. These individuals must be fully examined by an ophthalmologist (eye doctor) and the existing eye disease treated as best as possible. Proper visual acuity may not ever be fully restored with some of these conditions.

When two or more eye conditions exist, the person risks becoming functionally handicapped. The conditions need to be diagnosed and treated as soon as possible!

Some possible causes of poor night vision

1) Diabetes with diabetic retinopathy

2) Cataracts

3) Vitamin-A deficiency

4) Zinc deficiency

5) Over-exposure to sunlight

6) Retinitis pigmentosa

7) Myopia

Treatment of poor night vision or night blindness will include some of the following:

Cataracts are treated with surgery

Myopia can be corrected with prescription glasses

Vitamin A and Zinc deficiencies respond to nutritional supplements

Night blindness caused by congenital conditions such as retinitis pigmentosa tends to be permanent and requires a lifetime of monitoring by an eye doctor.

The best way to protect an individual from injury and accidents, due to uncorrected poor night vision or night blindness, is to avoid driving at night. Drive only during the daytime. The ability to react when driving a vehicle depends on healthy vision and healthy eyes. A 50-year-old driver may need twice as much light to see objects properly and as well as a 30 year old.

If driving at night must occur:

Increase visibility by cleaning vehicle windows and headlights.

Drive slowly to increase reaction time when danger threatens.

Individuals with night-vision problems should drive very slowly at nights, resisting all urgent to speed.