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Two-dimensional analysis of horizontal and vertical pursuit in infantile nystagmus reveals quantitative deficits in accuracy and precision

McIlreavy, Lee, Freeman, Tom and Erichsen, Jonathan 2020. Two-dimensional analysis of horizontal and vertical pursuit in infantile nystagmus reveals quantitative deficits in accuracy and precision. Investigative Ophthalmology & Visual Science 61 (6) , 15. 10.1167/iovs.61.6.15

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Abstract

Purpose: Infantile nystagmus (IN) presents with continuous, predominantly horizontal eye oscillations. It remains controversial whether those with IN have normal horizontal pursuit, while vertical pursuit has rarely been studied. We examined whether there are pursuit deficits associated with IN by investigating the effect of target direction, velocity, and amplitude. Methods: Twelve adults with idiopathic IN performed a pursuit task, a 0.4° dot moved either horizontally or vertically at 8 or 16°/s, through amplitudes of 8°, 16°, or 32°. Accuracy and precision errors were computed as bivariate probability density functions of target-relative eye velocities. Results: Eye velocity was less precise along the horizontal axis during both horizontal and vertical pursuit, reflecting the primary axis of the eye oscillation. Mean accuracy error along the target trajectory during vertical pursuit was just as impaired as during horizontal pursuit. There was a greater error in accuracy along the target trajectory for 16°/s targets than 8°/s. Finally, targets that oscillated at 2.0 Hz had a greater error in accuracy along the target trajectory than frequencies of 1.0 Hz or 0.5 Hz. When studied using the same experimental protocol, pursuit performance for typical observers was always better. Conclusions: These findings strongly support our hypothesis of severe deficits in pursuit accuracy in observers with IN for horizontally and vertically moving targets, as well as for targets that move at higher speeds or oscillate more quickly. Overall, IN pursuit impairment appears to have previously been underestimated, highlighting a need for further quantitative studies of dynamic visual function in those with IN.

Item Type: Article
Date Type: Publication
Status: Published
Schools: Optometry and Vision Sciences
Psychology
Publisher: Association for Research in Vision and Ophthalmology
ISSN: 0146-0404
Funders: BBSRC, College of Optometrists
Date of First Compliant Deposit: 30 March 2020
Date of Acceptance: 30 March 2020
Last Modified: 30 Jun 2020 14:31
URI: http://orca-mwe.cf.ac.uk/id/eprint/130648

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