Investigation Of Multifocal Visual Evoked Potential In Amblyopes

ObjectiveTo study the characteristic changes of multifocal VEP in anisometropic amblyopes and strabismic amblyopes, to evaluate the mechanism of amblyopia, and to provide the clinical instruction for the prognosis of amblyopia. MethodsThe multifocal pattern VEP of both eyes of 31 anisometropic amblyopes, 30 strabismic amblyopes and 30 normal subjects were recorded by VERIS Science?4.2 multifocal visual evoked response imaging system made of America EDI company. The latencies and amplitudes of P waves were analysed. Changes in different retinal area including the hemifields, quadrants, naso-temporal and different eccentricities were investigated by comparing the amblyopic eyes, the fellow eyes of the patients and the normal eyes. The relationship between the abnormality of the mVEP waveform and the visual acuity of the amblyopic eyes was studied. In anisometropic amblyopia group the relationship between the abnormality of the mVEP waveform and the degree of anisometropia was studied. And in strabismic amblyopia group, the relationship between the abnormality of the mVEP waveform and the angle of strabismus was studied. Results 1. Control study between the amblyopic eyes, the fellow eyes and the normaleyes.In this research we analysed the latencies and amplitudes of P waves betweenthe amblyopic eyes, the fellow eyes of the patients and the normal eyes, and compared the changes in diffent retinal area including the hemifields, quadrants, naso-temporal and different eccentricities.a. The amplitudes of P waves at six eccentricitiesAt six eccentricities the P waves of mVEP of the amblyopic eyes were reduced compared with the fellow eyes and the normal eyes. In anisometropic amblyopia group, there were no significant differences between the fellow eyes and the normal eyes. While in strabismic amblyopia group, there were differences between the fellow eyes and the normal eyes.b. The latencies of P waves at six eccentricitiesIn amblyopic eyes the latencies of P waves were markedly prolonged while no such changes of P waves were found in the fellow eyes.c. The latencies and amplitudes of P waves in upper and lower hemifieldsIn upper and lower hemifields, the P waves amplitudes of mVEP of the amblyopic eyes were reduced compared with the fellow eyes and the normal eyes. Reduced amplitudes of the fellow eyes were only found in strabismic amblyopia group but not in anisometropic amblyopia group. In amblyopic eyes the latencies of P waves were markedly prolonged compared with the fellow eyes and the normal. While there were no changes in the fellow eyes compared with the normal eyes.d. The latencies and amplitudes of P waves in nasal and temporal retinalhemifieldsIn anisometropic amblyopia group, there were no differences between the nasal and temporal retinal hemifields in mVEP of the amblyopic eyes and the fellow eyes. While in the esotropic amblyopia, the mean amplitude of mVEP in the nasal retinal hemifields was smaller than in the temporal retinal hemifields. Inamblyopic eyes the latencies of P waves were markedly prolonged while there were no such differences in the fellow eyes.2. The relationship between the abnormality of the mVEP waveform and the visual acuity of the amblyopic eyesAt all six eccentricities, the abnormalities of the mVEP were correlated with the damage of visual acuity of the amblyopic eyes, the worse the visual acuity of the amblyopic eyes, the larger the abnormality of the mVEP.3. In strabismic amblyopia group, the relationship between the angle of strabismus and the visual acuity of the amblyopic eyesThe angle of strabismus and the visual acuity of the amblyopic eyes showed no significant correlation.4. In anisometropic amblyopia group, the relationship between the degree of anisometropia and the difference of the visual acuityThere was no significant correlation between the degree of anisometropia and the difference of the visual acuity.5. In strabismic amblyopia group, the relationship between the abnormality of the mVEP waveform and the angle of strabismusIn the frist eccentricity, the abnormalities of the mVEP waveform were correlated with the angle of strabismus, the larger the angle of strabismus, the larger the abnormality of the mVEP waveform.But there were no such correlations in the other five eccentricities.6. In anisometropic amblyopia group, the relationship between the abnormality of the mVEP waveform and the degree of anisometropiaAt all six eccentricities, the abnormalities of the mVEP waveform weren't correlated with the degree of anisometropia. Conclusions...