Stereoscopic perception of 3-D images by patients after surgery for esotropia

Patients with esotropia (ET) have generally poor stereopsis; however, it is not clear whether they can see the recently developed 3-D images stereoscopically. We investigated the ability of postoperative ET patients to have stereoscopic perception of 3-D attraction images which have large crossed disparities, and also 3-D movies which have generally small uncrossed disparities.

Twenty-seven ET patients (infantile ET = 12, late-onset ET = 15) were examined postoperatively. They were examined with the 4-dot test, Titmus fly test, and questionnaires to determine whether they had stereoscopic vision when observing 3-D attraction images and 3-D movies. McNemar tests were used for statistical evaluations.

The number of patients who passed the Titmus fly test was smaller than the number that were able to see 3-D attraction images stereoscopically (fly test 13; 48 %, 3-D attraction 22; 81 %; P = 0.016). However, the number was not significantly different from that of those who could perceive 3-D movies stereoscopically. The number of patients who passed the Titmus fly test was significantly smaller than the number who can perceive 3-D attraction images stereoscopically in the infantile ET group (fly test 2, 17 %, 3-D attraction 10, 83 %; P = 0.013) but was not different in the late-onset ET group postoperatively. The minimum angle of fusion for the 4-dot test was smaller in the Titmus fly-positive patients than in the Titmus fly-negative patients (P = 0.03).

These results suggest that children who cannot pass the Titmus fly test might be able to experience 3-D attractions stereoscopically but not be able to see 3-D movies stereoscopically.