Orthoptic Treatment of Convergence Insufficiency in Parkinson's Disease: A Case Series

Professional perspective of vision therapy worldwide among optometrists and ophthalmologists

CLINICAL RELEVANCE

Perception of optometrists and ophthalmologists of vision therapy (VT) as well as their methods for performing the sessions is of great importance for understanding the problems that professionals face and what should be improved in their clinical practice.

BACKGROUND

The objective of this study was to determine the perception of VT and protocols used by eye care professionals globally.

METHODS

A cross-sectional study was performed among eye care professionals internationally. The participants completed via online (Google Forms) a questionnaire of 40 questions on their perception and clinical practice of VT. The survey only permitted one answer per email address and was only collected if professionals gave their consent to participate.

RESULTS

A total of 205 professionals from 43 countries answered the questionnaire (171 optometrists and 34 ophthalmologists). Accommodation and convergence problems were the main indication reported for VT (47.8%), followed by amblyopia (26.3%). The principal negative factor associated to VT was the limited number of professionals dedicated to this field (55.6%). The most common program of VT was the combination of VT sessions at home and at office (85.5%), with a great variability in terms of duration. Few professionals made use of the new technologies when programming VT, such as eye trackers (2.7%) or virtual reality (6.4%). European professionals surveyed had a more negative perception of VT (p < 0.031).

CONCLUSIONS

Eye care professionals globally perceive VT as a scientifically based procedure. Overall, they believe that it has low recognition and prestige, especially ophthalmologists. A great variability in the programming of VT sessions was found, which highlights the need for standardised protocols that professionals could follow in their clinical practice.

Professional perspective and practice patterns of vision therapy in Spain

CLINICAL RELEVANCE

An analysis of the professional perspective of vision therapy (VT) by eye care professionals allows understanding the current controversies about this therapeutic option of which aspects can be improved for its correct application in clinical practice.

BACKGROUND

The aim of the current study was to analyse the perception of VT and the clinical protocols in this context followed among optometrists and ophthalmologists in Spain.

METHODS

A cross-sectional survey among Spanish optometrists and ophthalmologists. Google Forms tool was used to collect data via an online questionnaire divided into 4 sections (40 questions): consent to participate, demographic characteristics, opinion of the professional perspective of VT, and protocols. Only one submission from each email address was permitted by the survey tool.

RESULTS

A total of 889 Spanish professionals answered (age, 25-62 years): 848 optometrists (95.4%) and 41 ophthalmologists (4.6%). VT was considered as a scientifically-based procedure by 95.1% of participants, but its recognition and prestige was considered as low. The main cause reported for this was bad reputation or perception of placebo therapy (27.3%). The main indication of VT according to the surveyed professionals was convergence and/or accommodation problems (72.4%). Significant differences were found in the perception of VT among optometrists and ophthalmologists (p ≤ 0.027). A total of 45.3% of professionals reported performing VT in their current clinical practice. A combination of training sessions in office and home was regularly prescribed by 94.5% of them, but with significant variability in the duration of such sessions.

CONCLUSIONS

VT is perceived by Spanish optometrists and ophthalmologists as a therapeutic option with scientific basis, but with limited recognition and prestige, although with more negative perception among ophthalmologists. A great variability was found in the clinical protocols followed between specialists. Future efforts should be focused on creating internationally recognised evidence-based protocols for this therapeutic option.

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

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:Thea priorihypothesis 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.

Neurophthalmologic and Orthoptic Ambulatory Assessments Reveal Ocular and Visual Changes in Patients With Early Alzheimer and Parkinson's Disease

Patients with Alzheimer's disease (AD) and Parkinson's disease (PD) develop a progressive decline of visual function. This condition aggravates overall cognitive and motor abilities, is a risk factor for developing hallucinations, and can have a significant influence on general quality of life. Visual problems are common complaints of patients with PD and AD in the early stages of the disease, but they also occur during normal aging, making it difficult to differentiate between normal and pathological conditions. In this respect, their real incidence has remained largely underestimated, and no rehabilitative approaches have been standardized. With the aim to increase awareness for ocular and visual disorders, we collected the main neurophthalmologic and orthoptic parameters, including optical coherence tomography (OCT), in six patients with a diagnosis of PD, six patients with a diagnosis of early AD, and eight control subjects in an easily assessable outpatient setting. We also evaluated the patient's ability to recognize changes in facial expression. Our study demonstrates that visual problems, including blurred vision, diplopia, reading discomfort, photophobia, and glare, are commonly reported in patients with PD and AD. Moreover, abnormal eye alignment and vergence insufficiency were documented in all patients during examination. Despite the small size of the sample, we demonstrated greater ganglion cell and retinal nerve fibers layer (RNFL) damage and a defect of facial emotion recognition in AD/PD patients with respect to a comparable group of normal elderly persons, with peculiarities depending upon the disease. Ocular defects or visual discomfort could be correctly evaluated in these patients and possibly corrected by means of lens, orthoptic exercises, and visual rehabilitation. Such a practical approach may help to ameliorate motor autonomy, reading ability, and may also reduce the risk of falls, with a positive impact in daily living activities.