Eye Diseases and Driver Fitness
Eye Diseases that affect Drivers
For most people, driving represents freedom, control and independence. Driving enables us to get to the places we want to go to at our own convenience. More importantly, to many others, it represents a means of earning a living.
Even though it seems so simple, driving is a complex skill. Your ability to drive safely can be affected by changes in your physical, emotional and mental condition.
One of the physical changes that can occur happens with respect to vision. 90% of the information we use in driving comes through seeing therefore good vision is essential for road safety. If you can’t see properly, you can’t drive safely.
Clear, comfortable vision will allow you to respond and react to road signs and other road users more quickly & accurately.
Any eye diseases or conditions that affect your vision will, in turn, affect your ability to drive safely.
Some of the leading causes of vision impairment in South Africa are cataracts, glaucoma, diabetic retinopathy and refractive errors.
A cataract is an opacity or “cloudiness” of the lens within the eye. When the lens becomes cloudy (much like the frosted glass in our bathroom windows), light cannot pass to the retina properly resulting in blurred vision.
Cataracts occur in different stages. In its early stages, it may be so small that it does not affect your vision and you may be able to drive safely for many years.
With time the cataract will worsen making your vision dull and blurry. Having a cataract can make it harder for you to see the road, street signs, other cars, and pedestrians.
You may find it more difficult to see things bright light and may have more trouble with glare from headlights.
Colours may look more faded and your night vision may get worse. Some people also experience difficulty with judging distances and have double vision as the cataracts progress.
Glaucoma is a condition in which the eye pressure becomes higher than the eye can tolerate. This is a painless condition that gradually damages the optic nerve.
It causes “tunnel vision” and affects your peripheral or “side” vision.
Depending on the stage of glaucoma, patients have a dull vision and have difficulty reading road signs especially in low light conditions.
This picture indicates the typical “tunnel vision,” that occurs in glaucoma.
Diabetic retinopathy or diabetic eye disease is damage to the retina of the eye from poorly controlled or long-standing diabetes. This can also result in visual impairment and may lead to blindness if not detected and/or treated timeously.
Some patients experience reduced peripheral vision, especially if laser treatment is needed. This affects the peripheral vision and makes driving (especially at night) unsafe.
Patients with diabetic retinopathy may see “blotchy” and blurred images like these.
Refractive errors are the most common eye disorders. Most people have a refractive error, i.e. the eye has an “error” in its ability to focus light correctly. The term “refractive error” refers to myopia (shortsightedness), hyperopia (far/long-sightedness), astigmatism and presbyopia. Refractive errors are usually easily corrected with spectacles or contact lenses.
Uncorrected refractive errors may make it more difficult to see traffic signs, pedestrians and other motorists as your ability to see at a distance are affected. This problem may be worse at twilight or at night.
Figure 1. Indicates the vision that a person with cataracts may experience - glare from headlights at night.
Figure 2. Myopia or short-sightedness causes blurred distance vision
Figure 3. Tunnel vision caused by loss of peripheral vision in glaucoma.
How to maintain good driving vision
- Have regular check-ups at your optometrist (at least every two years) to make sure that your vision is good.
- Keep the prescription for your glasses up to date and make sure your glasses are suitable for driving.
- Be aware of how your vision may change and how it can affect your driving. Modify your driving patterns to allow for some of these changes. For example, think about limiting or avoiding driving at night or twilight.
- Modify your car to help compensate for age-related changes in vision. For example, reduced side vision with age can be partly overcome by installing special mirrors on the car and making sure there are properly adjusted wing mirrors on both sides of the car.
- Keep your windscreen clean to reduce glare.