Ocular Motor Score (OMS): a clinical tool to evaluating ocular motor functions in children. Intrarater and inter-rater agreement

Assessing infant cognition in field settings using eye-tracking: a pilot cohort trial in Sierra Leone

OBJECTIVES

To investigate the feasibility of eye-tracking-based testing of the speed of visual orienting in malnourished young children at rural clinics in Sierra Leone.

DESIGN

Prospective dual cohort study nested in a cluster-randomised trial.

SETTING

8 sites participating in a cluster-randomised trial of supplementary feeding for moderate acute malnutrition (MAM).

PARTICIPANTS

For the MAM cohort, all infants aged 7-11 months at the eight sites were enrolled, 138 altogether. For controls, a convenience sample of all non-malnourished infants aged 7-11 months at the same sites were eligible, 60 altogether. A sample of 30 adults at the sites also underwent eye-tracking tests as a further control.

INTERVENTIONS

Infants with MAM were provided with supplementary feeding.

OUTCOME MEASURES

The primary outcomes were feasibility and reliability of eye-tracking-based testing of saccadic reaction time (SRT). Feasibility was assessed by the percent of successful tests in the infants. Reliability was measured with intraclass correlation coefficients (ICCs). Secondary outcomes were mean SRT based on nutritional state as well as and changes in mean SRT after supplementary feeding of MAM children.

RESULTS

Infants exhibited consistent orienting to targets on a computer screen (>95% of valid trials). Mean SRTs had moderate stability within visits (ICCs 0.60-0.69) and across the 4-week test-retest interval (0.53) in infants; the adult control group had greater SRT stability (within visit ICC=0.92). MAM infants had a trend toward higher adjusted SRT at baseline (difference=12.4 ms, 95% CI -2 to 26.9, p=0.09) and improvement in SRT 4 weeks thereafter (difference=-14 ms, 95% CI -26.2 to -1.7, p=0.025) compared with age-matched controls.

CONCLUSIONS

The results demonstrate the feasibility of eye-tracking-based testing in a resource-poor field setting and suggest eye-tracking measures have utility in the detection of group level effects of supplementary feeding.

Applicability of quantitative oculomotor and SARA assessment in children

BACKGROUND

In clinical practice, eye movements can provide an early diagnostic marker for early onset ataxia (EOA). However, quantitative oculomotor assessment is not included in the most frequently used and age-validated ataxia rating scale in children, the Scale for the Assessment and Rating of Ataxia (SARA). We aimed to investigate the applicability of semi-quantitative eye movement assessment by the International Cooperative Ataxia Rating Scale (ICARS_OCM) and Ocular Motion Score (OMS_7-10) complementary to SARA measurements in children.

METHODS

In 52 typically developing children (aged 4-16 years; n = 4 per year of age), three independent assessors scored saccadic eye movements and ocular pursuit according to the ICARS_OCM and matching parameters from the OMS_7-10. For ICARS_OCM, we determined 1) construct validity for coordinated eye movements by correlation with OMS_7-10, ICARS_{EYE-HAND-COORDINATION} and SARA subscale scores, 2) agreement percentage and inter-rater agreement (Fleiss Kappa) and 3) age-dependency.

RESULTS

Spearman's rank correlations of ICARS_OCM with OMS_7-10 and ICARS- and SARA subscales were moderate to fair (all p < .001). Inter-rater agreement of ICARS-_OCM was 80.8%; (Fleiss Kappa: 0.411). ICARS_OCM scores revealed a similar exponentially decreasing association with age as the other SARA (sub)scores, reaching a plateau at 10 years of age.

INTERPRETATION

ICARS_OCM has a valid construct for the measurement of coordinated eye movement performance and is reliably assessable in children. ICARS_OCM reveals a similar age-dependent relationship as the other ataxia subscales, reflecting the physiological maturation of the cerebellum. In children, these data may implicate that ICARS_OCM can reliably contribute to coordination assessment, complementary to the SARA subscales.

Ocular Motor Function in Children with Spastic Hemiplegia Evaluated by the Ocular Motor Score

PURPOSE

To assess the ocular motor functions in children with spastic hemiplegia by using the Ocular Motor Score (OMS).

MATERIAL

This study included 34 children, median age 11 years. The children were divided into 3 groups according to the underlying brain lesion; group 1 malformations, group 2 white matter damage of immaturity (WMDI), and group 3 cortical/subcortical lesions.

METHODS

The OMS protocol consists of 15 different subtests evaluating ocular motor functions. The OMS is divided into 2 parts, a static and a dynamic. The results from each subtest are scored 0, 0.3, 0.5, or 1, according to the level of disturbance, where 0 corresponds to normal function and 1 represents the maximum disability in the certain subtest. A total OMS (tOMS) between 0 and 15 can be obtained.

RESULTS

The median tOMS in the whole spastic hemiplegia group was 2.5 (range 1.3-5.8). The highest median tOMS 5.2 was seen in group 1, in the children with malformations. Strabismus was found in 45% (15/34) of the children, with an equal percentage in all 3 groups.

CONCLUSIONS

The children with spastic hemiplegia had a median tOMS of 2.7 and the highest median tOMS was seen in children with malformations. The OMS protocol is easy to use clinically and gives a quick overview of the patient´s ocular motor functions.

Clinical measurement of compensatory torsional eye movement during head tilt

PURPOSE

To measure the degree of compensatory torsional eye movement during head tilt using a fundus photography method.

METHODS

We enrolled 55 healthy subjects who were 20-66 years of age. Fundus photographs were obtained in the presumed baseline position and in stepwise head tilt positions to evaluate ocular torsion using a non-mydriatic fundus camera. Horizontal marks on the nose were photographed simultaneously to evaluate head tilt. Images were analysed using Photoshop to measure the degree of ocular torsion and head tilt.

RESULTS

A consistent compensatory torsional eye movement was observed in all subjects during head tilt. The degree of compensatory torsional eye movement showed a positive correlation with the angle of head tilt. Ocular torsional disconjugacy was observed during head tilt, with larger excycloductional eye movement than incycloductional eye movement (4.88 ± 2.91° versus 4.50 ± 2.76°, p < 0.001). In multiple linear regression analysis, the degree of compensatory torsional eye movement was significantly associated with the degree of head tilt (β = 0.191, p < 0.001), and the direction of cycloduction (β = -0.548, p < 0.001).

CONCLUSIONS

The fundus photography method is a non-invasive, accurate and objective tool for measuring compensatory torsional eye movement. Considering the availability of fundus photography in clinical ophthalmology practice, the proposed method can be used as a clinical tool to measure compensatory torsional eye movement.