Visual Attention and Saccadic Oculomotor Control in Parkinson's Disease

Abstract

Background: In patients with Parkinson's disease (PD) we aimed at differentiating the relation between selective visual attention, deficits of programming and dynamics of saccadic eye movements while searching for a target and hand-reaction time as well as hand-movement time. Visual attention is crucial for concentrating selectively on one aspect of the visual field while ignoring other aspects. Eye movements are anatomically and functionally related to mechanisms of visual attention. Saccadic dysfunction might confound selective visual attention in PD. Methods: We studied visual selective attention in 22 medicated PD patients (clinical ON status, mild to moderate disease severity) and 22 age matched controls. We looked for possible interferences through oculomotor deficits. Two tasks were compared: free viewing of photographs and time optimal visual search of a hidden target. Visual search times (VST), task related dynamics of saccades, and hand-reaction and hand-movement times were analyzed. Results: In the free viewing task mild to moderately affected PD patients did not differ statistically from healthy subjects with respect to saccade dynamics. However, patients differed significantly from healthy subjects in the time optimal visual search task with 25% lower rates of successful searches. Hand movement reaction time did not differ in both groups, whereas hand movement execution time was significantly prolonged in PD patients. Conclusion: Saccadic oculomotor control and hand movement reaction times were intact, whereas in our less severely affected treated PD patients, visual selective attention was not. The highly reduced successful search rate might be related to disturbed programming and delayed execution of saccades during time optimal visual search due to decreased execution of serial-order sequential generation of saccades.

Saccade frequency response to visual cues during gait in Parkinson's disease: the selective role of attention

“…SEM included hypothesised relationships entered between cognition, visual function, saccade frequency cue response and cued gait (Stuart et al ., ). Overall, the level of explained variance (13% gait impairment, 7% saccade frequency) and the relationship with attention are similar to previous saccadic (Buhmann et al ., ) and gait research in PD (Lord et al ., ) and older adults (MacAulay et al ., ). Our results highlighted that saccade frequency and gait with a visual cue were underpinned by attention rather than visual functions in PD.…”

Direct and indirect effects of attention and visual function on gait impairment in Parkinson's disease: influence of task and turning

“…Visual function only indirectly influenced these features, which was underpinned by attention. Levels of explained variance (10% gait impairment, 18% saccade frequency) and the relationship with attention concur with earlier saccadic (Buhmann et al ., ) and gait research in PD (Lord et al ., ) and older adults (Liu‐Ambrose et al ., ; MacAulay et al ., ). The remaining variance of both gait and saccade frequency may be due to numerous influences on these complex behavioural outcomes, such as; fatigue (Faber et al ., ), motivation (Kaplan et al ., ), prior knowledge of testing procedures (learning effect between walks; Kim & Rehder, ), emotional state (Oatley et al ., ), colour properties of the visual scene (Amano et al ., ) and saliency of objects (i.e.…”

The Neuro-Ophthalmological Assessment in Parkinson’s Disease

“…Inadequacy or slowness of accommodation can result in eyestrain, headaches and diplopia when working on near tasks. Abnormal convergence contributes to diplopia in 20-30% of PD patients [11,[43][44][45][46][47]. Referral to the ophthalmologist or orthoptist is indicated when the patient experiences problems in daily life (as indicated during the interview) or when test results are abnormal (Box 4), with special attention to convergence insufficiency.…”