Eye Movement Evaluation in Multiple Sclerosis and Parkinson's Disease Using a Standardized Oculomotor and Neuro-Ophthalmic Disorder Assessment (SONDA)

Abstract

Evaluating the state of the oculomotor system of a patient is one of the fundamental tests done in neuro-ophthalmology. However, up to date, very few quantitative standardized tests of eye movements' quality exist, limiting this assessment to confrontational tests reliant on subjective interpretation. Furthermore, quantitative tests relying on eye movement properties, such as pursuit gain and saccade dynamics are often insufficient to capture the complexity of the underlying disorders and are often (too) long and tiring. In this study, we present SONDA (Standardized Oculomotor and Neurological Disorder Assessment): this test is based on analyzing eye tracking recorded during a short and intuitive continuous tracking task. We tested patients affected by Multiple Sclerosis (MS) and Parkinson's Disease (PD) and find that: (1) the saccadic dynamics of the main sequence alone are not sufficient to separate patients from healthy controls; (2) the combination of spatio-temporal and statistical properties of saccades and saccadic dynamics enables an identification of oculomotor abnormalities in both MS and PD patients. We conclude that SONDA constitutes a powerful screening tool that allows an in-depth evaluation of (deviant) oculomotor behavior in a few minutes of non-invasive testing.

Abnormalities of the oculomotor function in type 1 diabetes and diabetic neuropathy

“…Indeed, the number of patients with T1D and neuropathy, in this study is limited, and the study selection process that excluded retinopathy but included neuropathy may have also inadvertently defined a sub-population of patients with some predisposition for early development of neuropathy, who could be further investigated for other disease markers [ 37 ]. The clinical relevance of this non-invasive test to identify and screen altered eye movement patterns has been already established in other neurologic diseases (e.g., amyotrophic lateral sclerosis, Alzheimer’s disease, Parkinson’s disease, multiple sclerosis, and epilepsy) [ 38 , 39 ], in which a cognitive disorder has been often recognized [ 19 ] and progression of the disease is hardly measurable [ 40 ]. Moreover, this method particularly recognizes alterations in rapid (saccades, velocity) and slow eye movements (smooth pursuit) and in some specific features (e.g., wideness and resistance), which are primarily under the control of the central nervous system.…”

Computational Methods for Continuous Eye-Tracking Perimetry Based on Spatio-Temporal Integration and a Deep Recurrent Neural Network

“…The final aspects to consider are comprehensiveness and ease of use. While SAP does only perimetry, the use of eye movements has two important clinical advantages: the data acquired for perimetry can simultaneously be used for additional neuro-ophthalmic evaluations ( Grillini et al, 2020 ). Moreover, according to patients, continuous gaze-tracking perimetry is less tiring and easier to perform than SAP ( Demaria et al, 2020 ).…”

“…Third, optimization of the stimulus properties. The current stimulus is the same used to extract the spatio-temporal properties of eye movements for neuro-ophthalmic screening ( Grillini et al, 2020 ), but it can be further optimized to perform visual field assessment. For instance, properties such as luminance contrast and speed can be adjusted to “lengthen the tail” of the normative distribution of TFCE values (see Figure 5B ), thus facilitating the thresholding between “healthy” and “impaired” values.…”

“…The simplicity and intuitiveness of this task make it significantly more practical than other types of perimetry, irrespective of whether they require a manual or eye-movement response from the patients ( Demaria et al, 2020 ). Furthermore, our approach provides a thorough quantification of both the spatio-temporal and statistical properties of both smooth pursuit and saccadic eye movements ( Grillini et al, 2020 ), thus having potential applications in neurology and neuro-ophthalmology as well.…”

Digital Biomarkers in Multiple Sclerosis

“…By now, eye-tracking tools have been used to detect pathologic visuo-spatial viewing behavior in MS [32]. New approaches present short assessments to capture abnormalities of the oculomotor system, such as SONDA (Standardized Oculomotor and Neurological Disorder Assessment) which takes less than five minutes for the whole assessment and is also used in Parkinson's disease [33]. Quick and standardized assessments allow regular monitoring over time without overburdening patients, especially those suffering from fatigue.…”