Study of the original and treatment of strabismus by EMG.

Research Project

Project/Area Number	62480365
Research Category	Grant-in-Aid for General Scientific Research (B)
Allocation Type	Single-year Grants
Research Field	Ophthalmology
Research Institution	Ehime University
Principal Investigator	TAMURA Osamu Ehime University, Ophthalmology Professor, 医学部, 教授 (10035404)
Co-Investigator(Kenkyū-buntansha)	ABE Machiko Ehime University, Ophthalmology Lecturer, 医学部, 講師 (80151108)
Project Period (FY)	1987 – 1989
Project Status	Completed (Fiscal Year 1989)
Budget Amount *help	¥3,900,000 (Direct Cost: ¥3,900,000) Fiscal Year 1989: ¥600,000 (Direct Cost: ¥600,000) Fiscal Year 1988: ¥500,000 (Direct Cost: ¥500,000) Fiscal Year 1987: ¥2,800,000 (Direct Cost: ¥2,800,000)
Keywords	esotropia / exotropia / visually evoked cortical potential / electro myo graphy / proprioception of the ocular muscles / 斜視 / Magician's / Forceps現象 / 伸張反射
Research Abstract	We have reported that the pathogenesis of strabismus is closely related to proprioceptive afferents. And it is supposed that the development of strabismus is under the influence of the visual input In this study, we demonstrated the proprioceptive afferent and visual input were cooperative for the developmental mechanism of strabismus. Cases studied here were esotropic patients aged from one year and two months to seven years and exotropic ones aged from fifteen to sixty two years. Visually evoked cortical potentials to flash stimulation (VECP) and electromyograph (EMG) were examined. Recordings of VECP were made from two electrodes located at O_2 and O_2. Monocular stimulation of each eye and binocular stimulation were used and the flash stimuli were projected to all visual fields of retina. EMGs of four horizontal rectal muscles were recorded either under general anesthesia for esotropic patients of children or in conscious patients with exotropia. In cases with esotropia, there was no difference in amplitude from both 0_1, and O_2 in binocular VECP. But in monocular VECP, we found the reduced amplitude. of contralateral VECP as compared with that of ipsilateral VECP. While all esotropic patients showed abnormal discharges in EMG, there was no difference in EMG in the patients with the disparities of amplitudes in monocular VECP. In exotropic patients we found no difference in monocular VECP and abnormal discharges in EMG. We suppose the mechanism of proprioception in exotropia affects the decussating optic system and that in esotropia acts on the non-decussating optic system. Because strabismus changes to be orthophorized under the light of less than 0.6 lux, the proprioceptive afferents might be In effect without visual input. Since some patients with esotropia showed the reduced amplitude of contralateral VECP monocularly stimulated, there may be a disorganization of devussated optic nerve fibers in esotropia.