[Clinical study on crossed disparity and uncrossed disparity in intermittent exotropia before and after surgery]

To understand the clinical variety of zero disparity, crossed disparity and uncrossed disparity in intermittent exotropia before and after strabismus surgery.

100 cases of intermittent exotropia were involved in the study. Before and after surgery, zero disparity stereo-acuity, crossed disparity and uncrossed disparity stereo-acuity were examined with stereogram designed by Yan Shaoming, distance fusion range and distance stereo-acuity were examined with traditional and random dot synoptophore stereogram. The patients were divided into four groups based on the results of the stereogram examination before surgery.

In the 100 cases, there was no coexistence of zero disparity and uncrossed disparity, no coexistence of crossed and uncrossed disparity, and no existence of only crossed disparity or only uncrossed disparity. Postoperative zero disparity, crossed disparity, uncrossed disparity, distance fusion range and distance stereo-acuity improved significantly compared with the preoperative results for each group (P < 0.01). The comparison of distance fusion range was not prominent before and after strabismus surgery in the 4 groups (P > 0.05). The distribution of distance stereo-acuity was prominent after strabismus surgery in the 4 groups (P < 0.01). Distance stereo-acuity rebuilding after surgery in group 1 and group 2 was better than that in group 3 and group 4.

(1) In the cases with intermittent exotropia, zero disparity stereo-acuity, crossed disparity and uncrossed disparity stereo-acuity are abnormal. The sequential damage of stereopsis is uncrossed disparity, crossed disparity and zero disparity. The sequential rebuilding of stereopsis is zero disparity, crossed disparity and uncrossed disparity. (2) The serious damage or disappearance of uncrossed disparity stereo-acuity is the indication of intermittent exotropia surgery for perfect binocular vision rebuilding.