Comparison of VEP Values in Acquired Esotropia with Exotropia

ABSTRACT

PURPOSE: To investigate about the influence of acquired strabismus, its angle and stereopsis on visual evoked potential (VEP). METHODS: This study included 30 accommodative esotropes and 30 intermittent exotropes aged 5 to 10, who had not undergone strabismus surgery. Partially accommodative esotropes were excluded. Angle of deviation, stereopsis, and refractve error were measured in all subjects. The values of VEP to monocular and binocular pattern stimulation were recorded. Statistical significances were tested by t-test and Kruskall-Wallis test. RESULTS: In intermittent exotropes, the P100 amplitude of deviating eye was smaller than that of normal eye in the test with 8 X 8 and 16 X 16 check size (p<0.05). There was no significant difference in accommodative esotropes. The P100 latency of binocular VEP using 16 X 16 check size was significantly short in intermittent exotropes, comparing to the normal eye. Angle of deviation and stereopsis did not influence on VEP. CONCLUSIONS: Acquired strabismus occurring beyond the end of the visual critical period can influence on VEP, but angle of deviation and stereopsis could not.