[Study on crossed and uncrossed disparity evoked potential of dynamic random dot stereogram].

OBJECTIVE

To analyze the disparity evoked potentials (DEP) of fine disparities, coarse disparities, crossed disparities and uncrossed disparities and provide parameters of impersonal examining stereopsis.

METHODS

A software package for generating dynamic random dot stereogram (DRDS) was developed as a visual stimulus to elicit DEP in 30 normal subjects. The DEP of every subject was recorded in different crossed and uncrossed disparity stimuli (4', 8', 15', 23', 30', 45', 53', 60', 72', 87', 102', 124', 150' of arc).

RESULTS

(1) the constant negative-positive complex wave was observed in different disparity stimuli. (2) The N wave's latency of -45' was the longest, the N wave's latency of -150' was the shortest among crossed disparities. The N wave's latency of 4', 23' was the longest, the N wave's latency of 124' was the shortest among uncrossed disparities. (3) The amplitude peak of P wave occurred at -23', -60', -150' among crossed disparities. The amplitude peak of P wave occurred at 15', 45', 72' among uncrossed disparities. (4) All characteristic crossed disparities were smaller than the uncrossed disparities. The change orderliness of small crossed disparities was different from that of small uncrossed disparities.

CONCLUSIONS

The N wave's latency and the P wave's amplitude can be used as parameters to impersonally examine stereopsis. These results suggest that stereopsis can be divided into fine crossed stereopsis, fine uncrossed stereopsis, coarse crossed stereopsis, and coarse uncrossed stereopsis.