ABSTRACT
Visual function is adversely affected in a great variety of ways in Parkinson’s disease (PD).1,2 Most of the visual dysfunction seen in this condition is relatively subtle from the patient’s and physician’s point of view. Although there are functional consequences under certain circumstances, the impairment resulting from visual symptoms in PD is seldom of sufficient severity to replace motoric dysfunction as the primary source of the patient’s clinical disability. The visual abnormalities linked to PD are, for the most part, demonstrable in the very early clinical phase of the illness and possibly in the preclinical phase as well. Parkinson’s disease is predominantly a disorder of the elderly, and patients in this age group commonly become aware of visual symptoms such as declining acuity, visual blurring, difficulty reading, impaired near vision, and abnormal light sensitivity. When these same symptoms occur in an elderly individual who also has PD, both the patient and the clinician may naturally wonder what contribution to these symptoms, if any, derives from the underlying neurological disorder. When visual complaints are formally solicited from PD patients, the most common are tired eyes or blurred vision when reading and diplopia.3 Can the origin of such complaints be linked to the known pathophysiology of Parkinson’s disease? To explore this possible relationship, this chapter will discuss the known aberrations of visual function that occur in PD as well as their pathogenesis. Since most forms of visual dysfunction in PD are clinically subtle, special attention will be paid to electrophysiologic and psychophysical techniques that are useful in demonstrating and quantifying them.
