Influence of motion smear on visual acuity in simulated infantile nystagmus.
Influence of motion smear on visual acuity in simulated infantile nystagmus.
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DOI：
10.1097/opx.0b013e31820846dd
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发表时间：
2011-02
期刊：
影响因子：
--
通讯作者：
Bedell HE
中科院分区：
文献类型：
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作者：
Chung ST;LaFrance MW;Bedell HE
在患有婴儿眼震（IN）的人中，视敏度与眼震波形的视觉聚焦期的持续时间相关，即，当视网膜图像在中央凹上或中央凹附近并且以低速移动时。在这项研究中，我们问敏锐度是如何影响的非foveating阶段的眼震波形，当视网膜图像运动的速度是相当高的。在三名正常观察者中测量高对比度、4方向Ts的视敏度，在模拟整个急动IN波形（全波形）或仅模拟IN波形的中心凹期（仅中心凹）的图像运动期间呈现。模拟的视觉聚焦持续时间范围从20到120毫秒。对于这两种运动波形，我们显示了不同数量的周期的敏锐度目标，以检查敏锐度是否受益于多个演示文稿的刺激。正如预期的那样，在全波形和仅注视点条件下，随着更长的模拟注视点持续时间，视力提高。在仅聚焦条件下，敏锐度始终优于全波形条件（约0.1 logMAR），表明模拟IN波形期间的高速图像运动具有不利影响。两种波形条件之间的敏锐度差异随着周期数的增加而增加，显然是因为在仅聚焦条件下而不是在全波形条件下跨周期进行求和。在正常观察者中，在存在模拟眼震波形的情况下的视敏度不仅受到视觉中心凹期的持续时间的限制，而且还受到波形的非视觉中心凹阶段的限制。然而，由于IN患者报告很少或没有与他们的眼震相关的运动拖尾，因此仍然不清楚在眼震波形的非中央凹阶段期间的快速视网膜图像运动是否在IN中产生类似的视敏度退化。
In persons with infantile nystagmus (IN), visual acuity correlates with the duration of the foveation period of the nystagmus waveform, i.e., when the retinal image is on or near the fovea and moves with low velocity. In this study, we asked how acuity is affected by the non-foveating phases of the nystagmus waveform, when the velocity of retinal image motion is substantially higher. Visual acuity was measured in three normal observers for high-contrast, 4-orientation Ts, presented during image motion that simulated either the whole jerk-IN waveform (whole-waveform) or only the foveation periods of the IN waveform (foveation-only). Simulated foveation durations ranged from 20 to 120 ms. For both motion waveforms, we displayed the acuity target for different number of cycles to examine if acuity benefits from multiple presentations of the stimulus. As expected, visual acuity improves with longer simulated foveation durations in both the whole-waveform and foveation-only conditions. Acuity is consistently better (by approximately 0.1 logMAR) in the foveation-only than the whole-waveform condition, indicating that the high-velocity image motion during the simulated IN waveform has a detrimental effect. This difference in acuity between the two waveform conditions increases with the number of cycles, apparently because summation occurs across cycles in the foveation-only condition but not in the whole-waveform condition. In normal observers, visual acuity in the presence of a simulated nystagmus waveform is limited not only by the duration of the foveation periods, but also by the non-foveating phases of the waveform. However, because persons with IN report little or no motion smear in association with their nystagmus, it remains unclear whether the rapid retinal image motion during the non-foveating phases of the nystagmus waveform generates a similar degradation of visual acuity in IN.