Relazione tra stereopsi e dominanza oculare sensoriale

Purpose: To quantify ocular sensory dominance and investigate its relationship to stereopsis.

Method: A total of 69 subjects participated in the study. Ocular dominance was measured by a continuous flashing technique, with the tested eye viewing a Gabor patch increasing in contrast, and the fellow eye viewing a Mondrian noise decreasing in contrast. In each trial, the log ratio of Mondrian to Gabor’s contrasts was recorded as a subject first detected the Gabor. We collected 50 trials for each eye and an interocular difference was analyzed with a rank-sum test. The z-value was used as the ocular dominance index (ODI) to quantify the degree of ocular dominance. A subject with ODI ≥ 2 was categorized as having a clear ocular dominance, and a subject with ODI < 2 was considered as having balanced eyes (unclear dominance). The stereoacuity was measured with random dot patterns with durations varying from 50 to 1000 ms. The best achievable stereoacuity (D_min) and the integration time needed to acquire that (T_min) were calculated.

Results: A total of 30 subjects had balanced eyes and 39 had clear ocular dominance. T_min was significantly longer in subjects with clear ocular dominance than in subjects with balanced eyes (180.18 vs. 121.17 ms, P < 0.01). T_min was positively correlated with ODI (P < 0.01). However, D_min in subjects with clear dominance was not different from that in subjects with balanced eyes (40.60 vs. 35.73 arcsec, P = 0.18).

Conclusions: Ocular dominance is not associated with how fine the stereoacuity is, but rather how quickly the best stereoacuity is acquired.

sorgente : http://iovs.arvojournals.org/article.aspx?articleid=2670515