ABSTRACT
Visual function is adversely affected in a great variety of ways in patients with Parkinson’s disease (PD) [1-3]. Most of visual dysfunction present in PD is relatively subtle from the patient’s and physician’s points of view, although there are practical functional consequences under certain circumstances. Still, the functional impairment resulting from visual symptoms in PD is seldom of sufcient severity to replace motoric dysfunction as the patient’s primary clinical complaint. The visual abnormalities linked to PD are, for the most part, already demonstrable in the very early clinical phase of the illness and possibly in the preclinical phase of PD as well. PD 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, difculty reading, impaired near vision, or abnormal light sensitivity. When these same symptoms occur in an older individual who has PD as well, both the patient and the clinician may naturally wonder what contribution, if any, has come from the underlying neurological disorder. When visual complaints are formally solicited from PD patients, the most frequent are difculty reading [3], tired eyes or blurred vision when reading, and diplopia [4]. Can the origin of such complaints be linked to the known pathophysiology of PD? 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 quantifying and demonstrating them.
