一种新型多空间频率眼优势度测量方法及其在弱视中的应用

A new method to measure the spatial frequency dependency of interocular suppression in amblyopia

目的利用眼间噪音掩盖技术结合快速对比敏感度测试技术（qCSF）测量弱视患者眼优势度，分析其可行性。方法实验研究。共10例成人弱视患者（弱视组）和17例正常成人对照者（正常组）参与了本研究。双眼先后作为测试眼和非测试眼，给非测试眼分别呈现空间滤波后的噪音和空白背景，测量测试眼的对比敏感度曲线，两者的差值即为非测试眼对测试眼的抑制度。测试时为有效地排除弱视眼对比敏感度损伤对测量结果造成的干扰，设定噪音图案的对比度值为噪音对比度阈值的5倍。数据采用重复测量的方差分析进行比较。结果弱视组不同空间频率抑制度大小眼间差异存在统计学意义（F=24．25，P〈0．01）；而正常组不同空间频率抑制度大小眼间差异无统计学意义（F=0.32．P〉0．05）。此外，弱视组的弱视眼对其对侧眼的抑制度显著低于正常组的非优势眼对其优势眼的抑制度（B24．29，P〈0．01）；弱视组对侧眼对弱视眼的抑制度略微高于正常组优势眼对其非优势眼的抑制度。但差异无统计学意义（F=3．81，P〉0．05）。结论弱视患者存在显著的眼间相互抑制不平衡，表现为弱视眼不能有效抑制对侧眼，而弱视对侧眼对弱视眼的抑制水平与正常人相当。我们认为这一现象可能是导致弱视患者双眼空间视觉损伤的基础。

Objective Using a standard dichoptie noise-masking paradigm combined with qCSF method to assess the inter ocular suppression at different spatial frequencies in adults with amblyopia normal controls. Methods Ten adults with anisometropia amblyopia and 17 normal controls participated this research study. The degree of interocular suppression was quantified by the threshold elevation when the untested eye viewed a band-pass filtered noise compared to that when the untested eye viewed an unstructured field of the same mean luminance. Monocular signal attenuation by the amblyopic eye was accounted for by setting the contrast of the noise mask to a 5 times of its detection threshold. Data were analyzed using repeated measured ANOVA. Results This method was efficient in measuring the interocular suppression in both amblyopes and normal controls. We also found symmetric interocular suppression for normals （F=0.32, P〉0.05）, but asymmetric interocular suppression for amblyopes （F=24.25, P〈0.01）. In particular, the suppression from the amblyopic eye to the fellow eye was significantly less than that found in the normal controls （F=24.29, P〈0.01）, while the suppression from the fellow eye to the amblyopic eye was not significantly different to that found in the normal controls （F=3.81, P〉0.05）. Conclusion Amblyopia involves an asymmetric interocular inhibition not accounted for by the signal attenuation of the amblyopic eye. This imbalance leads to dominance by the fellow eye over the amblyopic eye under binocular viewing （i.e. suppression）.