Refractive changes with post-rotatory nystagmus in healthy individuals.

Masakazu Hirota,Takao Hayashi,Ryusei Takigawa,Ryota Nakagomi,Chinatsu Okabe,Kakeru Sasaki,Kanako Kato

doi:10.1007/s10792-021-02028-0

Abstract

Post-rotatory nystagmus has been used to detect autism spectrum disorders in clinical settings. Although previous studies have focused on eye movements, they did not evaluate the change in ocular refraction during post-rotatory nystagmus. This study aimed to evaluate the changes in ocular refraction during post-rotatory nystagmus in healthy individuals. A total of 34 healthy volunteers (mean age ± standard deviation, 20.9 ± 0.6years) participated in this study. The ocular refraction during post-rotatory nystagmus was measured using MR-6000 (Tomey Inc.) on quick mode with a sampling rate of 30Hz under noncycloplegic and cycloplegic conditions. The amplitude of post-rotatory nystagmus was calculated on the basis of the anterior eye images, while the ocular refraction measurements were simultaneously recorded. The accommodative convergence per accommodation ratio was calculated using the heterophoria method. Video oculography was performed to measure the angle of convergence during post-rotatory nystagmus. The changes in ocular refraction during post-rotatory nystagmus were significantly greater under the noncycloplegic condition than under the cycloplegic condition. The changes in ocular refraction during the post-rotatory nystagmus were significantly and positively correlated with the amplitude of post-rotatory nystagmus under the noncycloplegic condition. The angle of convergence during post-rotatory nystagmus was significantly higher under the noncycloplegic condition than under the cycloplegic condition. The changes in the angle of convergence were significantly and positively correlated with the predicted accommodative convergence. These findings suggest that the accommodation was functional during the post-rotatory nystagmus to compensate for the retinal image slip, and the accommodative convergence can help weaken the nystagmus.

Highlights

Vestibulo-ocular reflex is the ability to stabilize the retinal image during head movement[1,2]
The changes in ocular refraction during post-rotatory nystagmus were significantly greater under the noncycloplegic condition than under the cycloplegic condition
The angle of convergence during post-rotatory nystagmus was significantly higher under the noncycloplegic condition than under the cycloplegic condition

Summary

Introduction

Vestibulo-ocular reflex is the ability to stabilize the retinal image during head movement[1,2]. Post-rotatory nystagmus is a transient horizontal nystagmus and is induced by lymphatic movement in the lateral semicircular canal of the inner ear due to rotational arrest[3,4]. Previous studies have reported that the duration of post-rotatory nystagmus was shorter in patients with ASD than in healthy individuals[5] and that the amplitude of post-rotatory nystagmus was larger in the patients with ASD than in healthy individuals[4]. These studies focused only on eye movements during post-rotatory nystagmus and did not evaluate the change in ocular refraction during post-rotatory nystagmus

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