Abstract
Purpose: :
The aim of this study was to obtain optokinetic (OKN) recordings in children with Cerebral Palsy (CP).
Methods: :
Binocular horizontal as well as vertical OKN recordings were obtained in 16 patients aged 1 year to 15 years. These patients also received detailed ophthalmologic clinical evaluation. In addition, monocular OKN recordings were obtained to determine the naso temporal asymmetry– a retrospective marker of binocular vision disruption.
Results: :
Binocular horizontal and vertical OKN recordings were tested and correlated to clinical findings. Absent horizontal OKN and vertical OKN was found in 3 patients. One of them had profound cortical visual impairment and the other two had gaze palsies. Also, nasotemporal asymmetry index was computed based on monocular OKN recordings as number of fast phases when viewing nasal–ward motion with the right eye plus number of fast phases when viewing nasal–ward motion with the left eye divided by number of fast phases when viewing temporal–ward motion with the right eye plus number of fast phases when viewing temporal–ward motion with the left eye. Equal responses to nasal–ward vs. temporal–ward motion will yield an index equal to 1 whereas a bias favoring nasal–ward target motion will yield an index greater than 1. Nasotemporal asymmetry was detected in 10 patients on OKN testing versus 8 patients on clinical exam.
Conclusions: :
Binocular OKN recordings were useful for documenting gaze palsies. In addition OKN testing in correlation with spatial sweep can determine tracking problems in children with cortical visual impairment and thus help predict the surgical outcomes for repair of strabismus/nystagmus. Also, monocular OKN testing quantifies nasotemporal asymmetry, which might be missed on clinical examination.
Keywords: electrophysiology: clinical • eye movements • binocular vision/stereopsis