A Study Of The Multiple Channel Visual Evoked Potentials In Constant Esotropic Patients

Objective: We study the characteristics of multi-channel visual evoked potentials(VEPs) in constant esotropic patients with and without amblyopia, in order to evaluate the mechanism of constant esotropia with and without amblyopia and find the objective methods for diagnosis .Methods: Multi-channel pattern reversal VEPs elicited by full field stimulation in monocularity and binocularity and half field stimulation in monocularity were recorded in constant esotropia with and without amblyopia and normal controls.Results: 1. The amplitude Nj-Pi (ANjPi) was decreased , and the latent period Pi(LPi) was longer in the amblyopic eye than that of the control group. 2. The AN^ was decreased , and the latent period Pi(LPi) was longer in the nonamblyopic fellow eyes , and dominant and non-dominant eyes of constant esotropic patients without amblyopia than that of the control group. 3. With full field stimulation, the amplitude NI-P! of binocular VEPs (AN,?]) was not higher than those of monocular VEPs in experimental group. These properties were different from those of control group. 4. There were significant differences in comparing LPi and ! between nasal-retina and temporal-retina of amblyopic eyes. Theof nasal-retina prolonged and the AN]?! decreased. Then, this phenominen didn't existed in the nonamblyopic fellow eyes and the constant esotropia without amblyopia. 5. With full field stimulation, esotropic amblyopia showed a "half field stimulation effecf'or an asymmetric distribution in the amblyopic eyes, and a minor " half field stimulation effect" also existed in the nonamblyopic fellow eyes and the constant esotropie without amblyopia.Conclusion : 1. It showed that visual passing channels was obstructed in esotropic amblyopia eyes. 2. Although the visual acuity is normal in the non-amblyopic fellow eyes of esotropic amblyopia and constant esotropia without amblyopia, their VEPs are abnormal to different extent. There might be dysfunction in visual passing channels. 3. It indicated that misalignmemt was an important factor that influenced binocular development. VEPs can provide a scientific basis for abnormal binocular vision in constant esotropia. 4. With half field stimulation, there is suppression in monocular VEPs of amblyopic eye nasal- retina and isn't suppression in non-amblyopic fellow eyes of esotropic amblyopia or constant esotropia without amblyopia. 5. The color mapping showed there was a positive activity shift in esotropic amblyopia eyes, a minor shift also existed in the nonamblyopic fellow eyes and the constant esotropie without amblyopia.