视物距离对知觉性优势眼的影响

目的研究基于Gabor识别的知觉性优势眼（OSD）是否会因视物距离的改变而发生变化。方法实验研究。OSD定量通过计算机辅助的心理物理学方法完成。经分视系统为60例健康受检者的两眼分别呈现Mordrian噪声和Gabor信号。在Mordrian噪声持续减弱而Gabor信号不断增强的过程中，受检者探测到Gabor信号的阈值被记录为眼知觉指数（OSI）。两眼各测试50次OSI。两眼间差异经标准化即为该受检者的眼优势指数（ODI）。ODI绝对值>2，则该受检者优势眼明确，OSI取值较小的眼别即优势眼别；否则无明确优势眼。分别在6 m的远距和60 cm的近距各进行一次测试。采用配对t检验测试ODI的变化是否显著。结果在距离对知觉性优势眼类型的影响的分析中，31例（52%）受检者的知觉性优势眼在远距和近距的检测中保持一致，26例（43%）受检者在不同距离下出现了有显著优势眼和无显著优势眼之间的转换，另有3例（5%）受检者出现了优势眼眼别的互换。在距离对知觉性优势眼影响的量化分析中，受检者的平均ODI由远距的－1.88±2.71变为近距的－0.72±2.95，表明在近距时知觉优势向平衡方向偏移（P＜0.01）。同时，45例（75%）受检者在远距某一眼相对优势的情况下，会在近距离检测中表现为优势向对侧眼（即原优势较弱眼）偏移的现象，另有15例（25%）受检者情况相反。向原优势较弱眼偏移的平均偏移量（2.66±0.32）明显大于向原优势较强眼的偏移量（1.04±0.25），差异有统计学意义（P＜0.01）。结论视物距离对知觉性优势眼存在影响。远距某一眼的知觉优势会在距离变近时向对侧眼发生偏移。近距视物时，双眼的知觉优势较远距更趋向平衡。

The effect of viewing distance on ocular sensory dominance

Objective To investigate whether ocular sensory dominance (OSD) changes with viewing distance.Methods Sixty subjects were enrolled in this perspective study.OSD was quantified by a computer-based psychophysics technique that involved the dichoptic presentation of a Mondrian noise and a Gabor patch.The threshold to detect the Gabor patch in the presence of a decreasing contrast of the Mondrian stimulus and increasing contrast of the Gabor stimulus was recorded as the ocular sensory index (OSI).OSI was measured at two different viewing distances,one for near at 60 cm and the other for far at 6 m.A t-test was used to compare the 50 OSI values collected from each eye,and the t-value was used as a subject's ocular dominance index (ODI).Results Qualitative analysis revealed that in 31(52％) subjects,the dominant eyes remained the same for both far and near conditions.In 3(5％) subjects,the dominant eyes switched at far and near distances.In the remaining subjects (26,43％),ocular dominance was unclear at either far or near.Quantitative analysis showed that the mean ODI changed from-1.88±2.71 at far to-0.72±2.95 at near,which indicated that ocular dominance tended to be more balanced at the near distance (P＜0.01).Moving from far to near,in the majority of the subjects (45,75％),sensory dominance shifted to the original weaker eye,and in only 15(25％) subjects did dominance drift further towards the original stronger eye.The mean amplitude shifting towards the weaker eye (2.66±0.32) was significantly larger than the amplitude shifting towards the stronger eye (1.04±0.25,P＜0.01).Conclusion Compared to viewing at far,the sensory dominance measured at near tends to shift to the original weaker eye,and leads to a more balanced binocular sensory dominance.