2010 BC Guide in Determining Fitness to Drive

Right homonymous hemianopiaBinasal hemianopiaLeft superior homonymous quadrantanopiaBitemporal hemianopiaAn important consideration related to hemianopia is the potential for anosognosia. Anosognosiais a condition in which a person with an impairment caused by a brain injury is unaware of theimpairment. Research indicates that hemianopic anosognosia is relatively frequent, occurring inapproximately two-thirds of those with hemianopia. Unawareness of visual field deficits has anobvious negative impact on safe driving performance.DiplopiaDiplopia (double vision) is the simultaneous perception of two images of a single object. Theseimages may be displaced horizontally, vertically, or diagonally in relation to each other.Diplopia can be binocular or monocular. Binocular diplopia is present only when both eyes areopen, with the double vision disappearing if either eye is closed or covered. Monocular diplopiais also present with both eyes open, but unlike binocular diplopia, the diplopia persists when theproblematic eye is open and the other eye is closed or covered.Binocular diplopia, or true diplopia, is an inability of the visual system to properly fuse theimages viewed by each eye into a single image. It may be caused by the physical misalignmentof the eyes (strabismus) or diseases such as Parkinson’s disease or multiple sclerosis. Two of themost common causes of binocular diplopia in people over 50 are thyroid conditions such asGrave’s disease, and cranial nerve damage.Monocular diplopia is not caused by misalignment, but rather by problems in the eye itself.Astigmatism, dry eye, corneal distortion or scarring, vitreous abnormalities, cataracts, and otherconditions can cause monocular diplopia.255