Cataracts are the most common aging change to affect the eyes. A cataract is a clouding of the lens of the eye. A cloudy lens blurs vision and decreases the amount of light entering the eye. A cataract change located in the center part of the lens can cause increased glare or dazzle. Visual acuity (sharpness of vision) may be severely affected, especially in rainy or foggy conditions or when driving at night. Cataract changes can even produce an extra image. All of these phenomena can affect day-today vision, and, of course, driving.
Fortunately, the surgery available to remove cataracts is highly advanced. The cataract is removed and a lens, called an intraocular lens implant, can be inserted into the eye. If the eye is otherwise healthy, vision is restored.
Macular degeneration is becoming more frequent as people live longer. The macula is a critical part of the retina which transforms light entering the eye into the images that transfer to the brain. In this disease, the tissues in the retina degenerate. This aging change in the macula (the center of the retina) can lead to blurred vision, distortion of vision, a change in colour vision, and a central blind spot (scotoma). If macular degeneration is complicated by hemorrhage (bleeding) or scar formation, a dense central blind spot can result. This can be large enough to stop a driver from seeing a pedestrian or a car in the line of vision.
Although there are important new treatment possibilities, management of macular degeneration is very difficult. Sadly, if you have macular degeneration with scarring in both eyes, there is no overlap of your vision to allow you to continue to drive a car. As well, we are increasingly aware of the importance of maintaining good general health in preserving the health of our eyes.
Glaucoma is another disease that can interfere with your ability to drive. In this condition the optic nerve, which transfers images from eye to brain, is damaged by increased pressure inside the eye. For many years, glaucoma has been thought of as a silent thief, since it gradually reduces peripheral (side) vision.
In driving, peripheral vision helps you to spot objects approaching from the side. It is especially important when passing through intersections. In end-stage glaucoma only a small central island of vision remains – not enough to allow safe driving. Unfortunately, glaucoma usually strikes silently and gradually. Many people are not aware of the condition until their visual field and optic nerve function are seriously damaged.
When it comes to glaucoma, an ounce of prevention is worth a pound of cure. Glaucoma testing involves measuring intraocular (inside the eye) pressure, and assessing the optic nerve and visual fields. Diagnosing and tracking people at higher risk for glaucoma can help save both their vision and potential accidents. The many treatments for glaucoma include eye drops, oral medication, laser therapy and surgical procedures. They all work to lower the pressure in the eye and preserve vision.
Cerebral vascular accidents or strokes can also affect vision and the ability to drive. In a classical stroke, half of the area of the brain involved in vision is affected. As a result, half of the visual field in each eye is missing. The peripheral vision so important to driving is affected. Also, some people can have strokes that affect only their vision, and not their walking, talking, or other functions. These strokes can steal the vision necessary to drive.
Preventing a stroke can be as simple as taking a low dose Aspirin™ (ASA) each day. It is very important that a stroke be treated quickly. Once damage is done to the part of the brain that serves the visual pathways, there is not much hope of significant recovery.