Stone D, Mathews S, Kruger P B
Schnurmacher Institute for Vision Research, State College of Optometry, State University of New York, NY 10010.
Ophthalmic Physiol Opt. 1993 Jul;13(3):244-52. doi: 10.1111/j.1475-1313.1993.tb00466.x.
When subjects view an edge in white light, a colour fringe, produced by longitudinal chromatic aberration (LCA) of the eye, is formed at the edge. The colour fringe changes with changes in focus, and serves as a complex colour-coded cue for reflex accommodation. Fincham found that 60% of his subjects failed to accommodate appropriately when the colour fringe was removed with an achromatizing lens or by the use of monochromatic light. Our experiment sought to determine the spatial frequencies at which LCA is most effective. We monitored accommodation in 10 subjects while they viewed sinusoidally moving sine-wave gratings (1-3 D at 0.2 Hz; 1-10.5 c/deg) in a Badal optometer. The targets were 'white' gratings with LCA normal, doubled, neutralized or reversed. Doubling the aberration has minimal effect, removing the aberration reduces gain and increases phase-lag, and reversing the aberration severely disrupts accommodation. Sensitivity to these chromatic cues exists at all spatial frequencies tested, but is most prominent between 3 and 5 c/deg. These results support the view that the system monitors focus by comparing contrast in red-green and perhaps blue-yellow colour-opponent mechanisms.
当受试者在白光下观察边缘时，眼睛的纵向色差（LCA）会在边缘处形成一个彩色条纹。该彩色条纹会随着焦点的变化而变化，并作为一种复杂的颜色编码线索用于反射性调节。芬奇姆发现，当使用消色差透镜或单色光消除彩色条纹时，60%的受试者无法进行适当的调节。我们的实验旨在确定LCA最有效的空间频率。我们在10名受试者通过Badal验光仪观察正弦移动的正弦波光栅（0.2Hz时为1 - 3D；1 - 10.5周/度）时监测其调节情况。目标是具有正常、加倍、中和或反转LCA的“白色”光栅。使像差加倍影响最小，消除像差会降低增益并增加相位滞后，而反转像差会严重干扰调节。在所测试的所有空间频率下都存在对这些颜色线索的敏感性，但在3至5周/度之间最为显著。这些结果支持了这样一种观点，即该系统通过比较红 - 绿以及可能的蓝 - 黄颜色对立机制中的对比度来监测焦点。
