Preliminary report: Dynamic stereopsis in patients with impaired binocular function.

In this study, 46 strabismic patients aged between 9 and 58 years were tested for dynamic stereopsis in the peripheral visual field with up to 20 degrees eccentricity. Squint angles ranged from +30 to -36 degrees. The effect of surgical realignment of the visual axes on dynamic stereopsis was tested before and after surgery in 40 of these patients. Of the 46 patients, 23 had esotropia and 23 exotropia. A test device was used which presented two projected squares in polarized light (each square being perceived monocularly through a polarization filter) in horizontal motion, thus creating a three-dimensional impression. Patients were tested qualitatively for dynamically stereoactive fields of vision and quantitatively for the threshold value needed to create a three-dimensional impression. We found residual dynamic stereopsis in 30% of patients who had no central static stereopsis. 56% of the patients improved after surgery, either through a significant (p < 0.01) gain of stereoactive fields or through a decrease in threshold values. This emphasizes the necessity of creating a test device suitable for everyday clinical use. Strabismus surgery is especially beneficial in connection with traffic and sports medicine, regardless of the effect on classical tests.