[A clinical observation on variation of crossed disparity and uncrossed disparity in intermittent exotropia].

OBJECTIVE

To understand the clinical variety of crossed disparity and uncrossed disparity in intermittent exotropia.

METHODS

Zero disparity stereo-acuity, crossed disparity and uncrossed disparity stereo-acuity of 55 cases with intermittent exotropia were examined with stereogram designed by Yan Shaoming before surgery.

RESULTS

In group 1 consisting of 25 cases, the zero disparity stereo-acuity of normal persons was 48%, the values of crossed disparity and uncrossed disparity stereoacuity were not in the normal range, and the crossed disparity was larger than the uncrossed disparity stereo-acuity (t = 843.5, P < 0.000 1). In group 2 including 26 cases, the zero disparity stereo-acuity of normal person was 30.8%, the value of crossed disparity was abnormal, and the uncrossed disparity was not found. In group 3 consisting of 4 cases, only the abnormal zero disparity stereo-acuity was found. In the 55 cases, there was no coexistence of zero disparity and uncrossed disparity, no existence of only crossed disparity or only uncrossed disparity, and no coexistence of crossed and uncrossed disparity.

CONCLUSIONS

(1) In the cases with intermittent exotropia, the zero disparity stereoacuity, the crossed disparity and uncrossed disparity stereoacuities are abnormal. (2) The sequential damage of stereopsis in intermittent exotropia is uncrossed disparity, crossed disparity and zero disparity. (3) It is proved in the clinic that the binocular temporal retinae correspond to the crossed disparity and the binocular nasal retinae correspond to the uncrossed disparity.