Changing vergence function in persons with Parkinson's disease and convergence insufficiency

Oculomotor assessment is an essential element of the neurological clinical examination and is particularly important when evaluating patients with movements disorders. Most of the brain is involved in oculomotor control, and thus many neurological conditions present with oculomotor abnormalities. Each of the different classes of eye movements and their features can provide important information that can facilitate differential diagnosis. This educational review presents a clinical approach to eye movement abnormalities that are commonly seen in parkinsonism, ataxia, dystonia, myoclonus, tremor, and chorea. In parkinsonism, subtle signs such as prominent square wave jerks, impaired vertical optokinetic nystagmus, and/or the “round the houses” sign suggest early progressive supranuclear gaze palsy before vertical gaze is restricted. In ataxia, nystagmus is common, but other findings such as oculomotor apraxia, supranuclear gaze palsy, impaired fixation, or saccadic pursuit can contribute to diagnoses such as ataxia with oculomotor apraxia, Niemann‐Pick type C, or ataxia telangiectasia. Opsoclonus myoclonus and oculopalatal myoclonus present with characteristic phenomenology and are usually easy to identify. The oculomotor exam is usually unremarkable in isolated dystonia, but oculogyric crisis is a medical emergency and should be recognized and treated in a timely manner. Gaze impersistence in a patient with chorea suggests Huntington's disease, but in a patient with dystonia or tremor, Wilson's disease is more likely. Finally, functional eye movements can reinforce the clinical impression of a functional movement disorder.

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“… 57–59 It can cause blurred near vision, which can significantly impact the quality of life. Convergence training is a treatment option 60 …”

Section: Phenomenologymentioning

confidence: 99%

Eye Movement Disorders in Movement Disorders

Kassavetis

Kaski

Anderson

et al. 2022

Movement Disord Clin Pract

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“…in 2008 and suggested that eye movement exercises may improve gaze control in PwP, with carry over improvement in gait if combined with balance exercises [29,30]. Similarly, a more recent study demonstrated a significant improvement in convergence insufficiency following two months of eye-movement training (vergence therapy) in a small cohort of PwP [31] While the findings of previous studies have contributed to the growing interest in the effects of eye-movement training in PwP [32][33][34], the treatments described in these trials often involve participants having to attend multiple training sessions per week at a laboratory/clinic/hospital or performing repetitive activities, such as pencil push ups several times per day [31]. Previous studies were limited by small sample sizes, strict inclusion criteria, and the burdensome protocols that resulted in significant drop-out rates and low participant uptake, which all limit the generalisability to clinical practice.…”

Section: Introductionmentioning

confidence: 97%

Exploring the feasibility of technological visuo-cognitive training in Parkinson’s: Study protocol for a pilot randomised controlled trial

Das

Morris²,

Barry³

et al. 2022

PLoS ONE

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Visual and cognitive dysfunction are common in Parkinson’s disease and relate to balance and gait impairment, as well as increased falls risk and reduced quality of life. Vision and cognition are interrelated (termed visuo-cognition) which makes intervention complex in people with Parkinson’s (PwP). Non-pharmacological interventions for visuo-cognitive deficits are possible with modern technology, such as combined mobile applications and stroboscopic glasses, but evidence for their effectiveness in PwP is lacking. We aim to investigate whether technological visuo-cognitive training (TVT) can improve visuo-cognitive function in PwP. We will use a parallel group randomised controlled trial to evaluate the feasibility and acceptability of TVT versus standard care in PwP. Forty PwP who meet our inclusion criteria will be randomly assigned to one of two visuo-cognitive training interventions. Both interventions will be carried out by a qualified physiotherapist in participants own homes (1-hour sessions, twice a week, for 4 weeks). Outcome measures will be assessed on anti-parkinsonian medication at baseline and at the end of the 4-week intervention. Feasibility of the TVT intervention will be assessed in relation to safety and acceptability of the technological intervention, compliance and adherence to the intervention and usability of equipment in participants homes. Additionally, semi structured interviews will be conducted to explore participants’ experience of the technology. Exploratory efficacy outcomes will include change in visual attention measured using the Trail Making Test as well as changes in balance, gait, quality of life, fear of falling and levels of activity. This pilot study will focus on the feasibility and acceptability of TVT in PwP and provide preliminary data to support the design of a larger, multi-centre randomised controlled trial. This trial is registered at isrctn.com (ISRCTN46164906).

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“…vergence) results in compromised depth perception and spatial navigation in up to 70% of PD patients [4]. Misalignment of the two eyes due to abnormal vergence leads to strabismus and impaired visual fusion, causing diplopia (double vision) in about a third of PD patients [7][8][9][10]. Vergence latency increases, and velocity decreases in PD [7,10].…”

Section: Introductionmentioning

confidence: 99%

“…Misalignment of the two eyes due to abnormal vergence leads to strabismus and impaired visual fusion, causing diplopia (double vision) in about a third of PD patients [7][8][9][10]. Vergence latency increases, and velocity decreases in PD [7,10]. The Visual Function Questionnaire-25 (VFQ-25) that measures the impact of visual symptoms on quality of life demonstrated significantly poor outcomes in PD patients.…”

Section: Introductionmentioning

confidence: 99%

Computational models to delineate 3D gaze-shift strategies in Parkinson’s disease

Gupta¹,

Beylergil²,

Murray³

et al. 2021

J. Neural Eng.

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Objective: Parkinson’s disease (PD) frequently affects vergence eye movements interfering with the perception of depth and dimensionality critical for mitigating falls. We examined neural strategies that compensate for abnormal vergence and their mechanistic underpinning in PD. Approach: The a priori hypothesis was that impaired vergence is compensated by incorporating rapid eye movements (saccades) to accomplish gaze shifts at different depths. Our experiments examined the hypothesis by simulating biologically plausible computational models of saccade-vergence interactions in PD and validating predictions in the actual patient data. Main results: We found four strategies to accomplish 3D gaze shift; pure vergence eye movements, pure saccadic eye movements, combinations of vergence followed by a saccade, and combination of saccade followed by vergence. The gaze shifting strategy of the two eyes was incongruent in PD. The latency of vergence was prolonged, and it was more so when the saccades preceded the vergence or when the saccades only made 3D gaze shift. Computational models predicted at least two possible mechanisms triggering saccades along with vergence. One is based on the lack of foveal accuracy when the vergence gain is suboptimal. The second mechanism reflects the noise in the gating mechanism, the omnipause neurons, for vergence and saccades. None of the two model predictions alone were completely supported by the patient data. However, a combined model incorporating both abnormal vergence velocity gain and impaired gating accurately simulated the results from PD patients. Significance: The combined strategy is biologically plausible for two reasons: (a) The basal ganglia that is prominently affected in PD projects to the vergence velocity neurons in the midbrain via the cerebellum. The projection directly affects the vergence velocity gain. (b) The basal ganglia, via superior colliculus, influences the pattern of omnipause neuronal activity. Abnormal basal ganglia activity may introduce noise in the omnipause neurons.

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Changing vergence function in persons with Parkinson's disease and convergence insufficiency

Cited by 7 publications

References 4 publications

Eye Movement Disorders in Movement Disorders

Eye Movement Disorders in Movement Disorders

Exploring the feasibility of technological visuo-cognitive training in Parkinson’s: Study protocol for a pilot randomised controlled trial

Computational models to delineate 3D gaze-shift strategies in Parkinson’s disease

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