Visual Symptoms in Parkinson's Disease

Table 1

Visual signs and symptoms of Parkinson's disease (PD).

Ocular aspect	Change in PD	References
Visual acuity	Poor, especially at low contrast	[6]
		[4]
Colour vision	Vision blurred for coloured stimuli	[8]
	Shortened colour fusion time	[9]
	Progressive deterioration	[10]
Visual fields	Increase in glaucomatous visual field defects	[13]
	Side effects of surgery	[14]
Saccadic eye movement	Reaction time and max. velocity of horizontal gaze slower	[15]
	Hypometria	[16]
	Amplitude increased after cued saccades	[17]
Smooth pursuit movement	Affected early in disease process	[20]
	Superimposed saccades	[15]
	Reduction in response magnitude	[15]
Optokinetic Nystagmus	Abnormal in some patients	[15]
Convergence	Impaired, associated with large exophoria, diplopia	[21]
		[22]
Blink frequency	Reduced, causing abnormal tear film, dry eye and reduced vision	[23]
Blink reflex	Habituation not observed	[24]
Pupil diameter	Larger after light adaptation with anisocoria	[26]
Light reflex	Longer latency
Constriction time	Increased	[26]
Contraction amplitude	Reduced	[23]
Contrast sensitivity (CS)	Abnormal in some cases, intermediate to high frequencies	[28]
Temporal processing	Impaired ability to track rapid fluctuations	[32]
	Duration perception affected	[33]
Flash ERG	Reduced amplitude of “b” wave	[35]
PERG	Reduced amplitudes.	[35]
	Specific defect at medium SF
	Delayed P50	[36]
Cortical VEP	Delayed P100	[45]
		[46]
Chromatic VEP	Increased latency and reduced	[44]
	Amplitude (esp. blue-yellow)
ERP	Abnormal. Delayed reaction times	[42]
		[41]
Visuo-spatial	Difficulty in judging verticals,	[48]
	position of body parts, and in route-walking tasks	[49]
Orientation and motion discrimination	Impaired	[50]
Facial perception	Impaired ability to perceive and imagine emotional faces	[51]
Visual hallucinations	Chronic in 30–60% of treated cases	[54]

Abbreviations: ERG: Electroretinogram, ERP: event-related potentials, PERG: Pattern electroretinogram, SF: Spatial frequency, VEP: Visual evoked potentials.