Automated alternate cover test for ‘HINTS’ assessment: a validation study

Abstract

Objective The alternate cover test (ACT) in patients with acute vestibular syndrome is part of the ‘HINTS’ battery test. Although quantitative, the ACT is highly dependent on the examiner’s experience and could theoretically vary greatly between examiners. In this study, we sought to validate an automated video-oculography (VOG) system based on eye tracking and dedicated glasses. Methods We artificially induced a vertical strabismus to simulate a skew deviation on ten healthy subjects, aged from 26 to 66, using different press-on Fresnel prisms on one eye while recording eye position with VOG of the contralateral eye. We then compared the system’s performance to that of a blinded trained orthoptist using conventional, semi-quantitative method of skew measurement known as the alternate prism cover test (APCT) as a gold standard. Results We found a significant correlation between the reference APCT and the Skew VOG (Pearson’s R2 = 0.606, p < 0.05). There was a good agreement between the two tests (intraclass correlation coefficient 0.852, 95 CI 0.728–0.917, p < 0.001). The overall accuracy of the VOG was estimated at 80.53% with an error rate of 19.46%. There was no significant difference in VOG skew estimations compared with the gold standard except for very small skews. Conclusions VOG offers an objective and quantitative skew measurement and proved to be accurate in measuring vertical eye misalignment compared to the ACT with prisms. Precision was moderate, which mandates a sufficient number of tests per subject.

Quantitative Oculomotor Assessment in Hereditary Ataxia: Systematic Review and Consensus by the Ataxia Global Initiative Working Group on Digital-motor Biomarkers

“…Before initiating a recording session, we recommend that both an assessment for ocular alignment and a calibration should be performed. To assess for ocular alignment, both a cover/uncover test and an alternate cover test should be done (and recorded if binocular recording devices are used) while looking straight-ahead, measuring any ocular deviation angle [ 40 , 41 ]. The alternate cover test allows the identification of any skew deviation (i.e., vertical divergence or vertical tropias), and the cover/uncover test can reveal horizontal tropias.…”

Akutes zentrales vestibuläres Syndrom

“…Es gibt Hinweise, dass die Bestimmung der Zeitkonstante einen pathologischen Blickrichtungsnystagmus (bei zentralen Läsionen) von einem physiologischen Blickrichtungsnystagmus unterscheiden kann (Schwellenwert: < 18 Sekunden) 34 . Auch die Vertikaldeviation der Augen kann apparativ quantifiziert werden 45 . Ein vertikaler Divergenzwinkel > 3,3° könnte als relativ spezifisch für zentrale Schwindelursachen des AVS sein 35 .…”

Updates in neuro-otology

“…Removal of visual fixation tends to augment peripheral vestibular nystagmus more than central nystagmus, and patients with AUVP often have higher slow phase velocities [18 & ], findings that can be difficult to appreciate without the aid of VOG. Video-oculography-HINTStest of skew VOG has demonstrated high accuracy in detecting skew deviation [19]. Typically, the presence of a skew deviation should be seen as a central sign.…”

“…VOG has demonstrated high accuracy in detecting skew deviation [19]. Typically, the presence of a skew deviation should be seen as a central sign.…”