The relationship between vision and driving

Eye care

Driving vehicles and all types of heavy machinery is a difficult and dangerous task in which multiple factors come into play, the most important of all being quality of view. 90% of the information we get while driving comes through vision, so it is obvious that visual conditions are extremely influential for good driving practice, and are often related to accidents caused by human error.

When driving, good quality of vision is necessary, which is defined by the right balance between the different aspects that make up the visual function: visual acuity, depth of vision, visual field, adaptation to light, changes in color vision, and ocular motility. All eye disorders or diseases that involve a decrease or lack of one or more of these aspects will result in less robust and substandard vision. Drivers so challenged can be more at risk of errors when calculating distances between cars and vehicle speed when driving under less-than-optimal conditions (owing to either low-visibility weather or physiological conditions, such as night driving and/or fatigue).

Up to what age can one drive a car within the limits of declining vision?
It is estimated that visual aging begins to manifest after age 45, and reaches significant levels from 65 onward (decreased visual acuity; depth of view of the visual field is reduced; it becomes more difficult to adapt to the dark; there is increased sensitivity to glare, leading to greater difficulty driving at night, while requiring a greater intensity of light to see properly). Also, with age, physiological alterations or ocular diseases may come into play (as well as other diseases that indirectly affect vision).

Eye diseases (such as glaucoma, cataracts, retinopathy, etc.) or the pathologies that produce declines in vision (diabetes or hypertension) do not always lead to loss of visual health, depending on the condition and control of the disease. However, there are times when these conditions can progress to blindness. Only regular monitoring by doctors or specialized opticians and optometrists can detect any impairment and prescribe appropriate treatment to slow or even reverse the disease. It is easy to identify those conditions in which vision loss is sudden, but gradual loss cannot be overlooked, and may be too late to be treated when if undetected for too long.

What are the risks of driving at night?More serious accidents involving a greater number of passengers usually occur at a higher rate during night driving. This means that nighttime driving requires having better vision and that it is of good quality. Visual acuity in low light levels may decrease down to 20% of normal, which is aggravated if some added visual impairment is also in play (severe myopia, retinopathy, cataracts, glaucoma, etc.)

How does eye fatigue affect driving?
Eyestrain is related to refractive visual defects (myopia, hyperopia, and especially in the case of astigmatism); as well as disorders of ocular motility (strabismus, phoria, nystagmus , etc.); dry eye that is evident after prolonged driving at high speed, night driving, heavy traffic and consumption of tobacco, alcohol, medicine and recreational drugs. It is manifested by blurred vision, tearing, fatigue, photophobia, double vision, eye pain, grittiness, dryness, redness, burning, or heaviness. Sometimes these are accompanied by headache, nausea, or dizziness.

How do I care for my vision with regards to safe driving?

Do not wait for your driver’s license to expire in order to take an eye examination. In Òptica Balear, you can request a vision exam for the vision-approval aspect of driver certification at any time.
If you wear prescription glasses, always wear the proper graduation, use clean lenses without scratches, carry a pair of replacement glasses as a compulsory safety measure in the car, and check your sight each year by visiting your ophthalmologist. Having only slightly impaired vision, say, a few diopters, by no means signifies that eyeglasses or contacts are not need to drive in a 100% secure manner.
Wear sunglasses to protect your eyes from sunlight. Buy them in specialized outlets, such as any retail facility operated by Òptica Balear in Mallorca. Make sure these sunglasses do not have excessive filtering, because otherwise, in twilight or in a tunnel, you will not have good vision. Gray-tinted sunglasses are apt for all drivers, green-tinted for hyperopic people, and for myopic drivers or those without visual defect, the tint should be preferably brown.
If you have a visual impairment or disease (such as visual acuity less than the normal limit, cataracts, glaucoma, or retinal damage), try driving on safer highways and interstate roads, increase the safety distance behind vehicles ahead, drive more slowly, avoid long journeys, rest every hour, and try not to drive in low light situations (dawn, dusk or at night).
Get periodic ophthalmologic examinations in specialized centers that can provide complete assurances in their diagnoses.
If you notice vision changes (such as having blurred vision, seeing better up close than before, seeing better without glasses, experiencing more visual fatigue than usual, increased feeling of sensitivity to glare at night, or visualization of ‘luminous rings’ around vehicle headlights), have your eyes checked by an ophthalmologist.
If you have been operated on for astigmatism, nearsightedness, farsightedness, cataracts, glaucoma, etc., do not drive until so directed by your ophthalmologist, and avoid driving for long periods at night.
Those drivers who suffer disorders in color vision should increase precautions under adverse weather conditions, as well as increase the safety distance behind vehicles ahead because they cannot perceive taillights braking well, especially if they are very dark or dirty. Exhaust from gas burning engines, excess alcohol and tobacco, certain medications and other drugs may also alter color perception.
Prevent eye fatigue by increasing the rate of blinking, especially if you wear contact lenses. Use air conditioning sparingly. Avoid windy drafts from windows. It is advisable not to smoke inside the car. Avoid driving at night, heavy traffic and stressful situations. Avoid driving without sunglasses on sunny days or in beach areas or snow. If you feel the need to rub your eyes or close them for you to rest, stop the car, and rest or take a nap.
Avoid driving at night as much as possible, especially if you have glaucoma, and/or if you are more than 65 years old, or suffer from myopia or cataracts. Avoid driving after surgery for visual problems during the time recommended by your physician. Tinted windshields and the use of colored glasses are detrimental to proper visual function during night driving. Maintain your headlights aligned and free of obstructing dirt and dust. If you routinely drive at night, or are over 60 years of age, increase the intake of vitamin A in your diet (carrots, oranges, tangerines, lettuce, spinach, melons, bananas, fish and corn oil, etc.)
To avoid glare, maintain your windshield free of dirt and dust, as well as free of scratching. The same applies to your eyeglasses (if you use them).
Drive at the right speed. Driving at higher speeds decreases the field of view considerably (narrowing it), requires greater attention and concentration, and accelerates eyestrain and fatigue.