Abstract
Purpose::
Accurate objective measurement of cyclovertical ocular motility is challenging both clinically and in the research lab. Our purpose is to validate the utility and accuracy of a novel haploscope so that it can be used to learn more about the mechanisms underlying normal eye control as well as to help explain the mechanisms of cyclovertical strabismus in pediatric and adult subjects.
Methods::
We have developed a novel haploscope allowing the measurement of eye movements under specified conditions of vergence, head tilting, and cover testing. Equipped with video oculography, the haploscope enables the objective assessment of binocular and adaptive mechanisms that maintain ocular motor alignment. We performed detailed measurements using a gimbal and also examined the well documented phenomenon of ocular counter roll to test the device’s ability to measure ocular torsion reliably and accurately. Six normal subjects fixated on the center of radially symmetric targets during head tilting, eye movements were recorded, and both intra- and inter-subject repeatability were measured.
Results::
Measurements consistent with tolerances on the order of 30 arc minutes. Ocular counter roll averaged 5.5o for left and right eyes with good comitancy. One subject with otherwise normal neurologic and ophthalmologic function did not make ocular counter roll movements.
Conclusions::
These results validate the device’s design and utility in studying eye movements. While ocular counter roll occurred in the majority of subjects, it is not a universal or necessary requirement for normal ocular alignment.
Keywords: eye movements: recording techniques • neuro-ophthalmology: diagnosis • strabismus