Mon-Williams M, Tresilian J R, Strang N C, Kochhar P, Wann J P
Department of Human Movement Studies, University of Queensland, St Lucia, Australia.
Proc Biol Sci. 1998 Jan 7;265(1390):71-7. doi: 10.1098/rspb.1998.0266.
Anecdotal reports abound of vision improving in myopia after a period of time without refractive correction. We explored whether this effect is due to an increased tolerance of blur or whether it reflects a genuine improvement in vision. Our results clearly demonstrated a marked improvement in the ability to detect and recognize letters following prolonged exposure to optical defocus. We ensured that ophthalmic change did not occur, and thus the phenomenon must be due to a neural compensation for the defocus condition. A second set of experiments measured contrast sensitivity and found a decrease in sensitivity to mid-range (5-25 cycles deg-1) spatial frequencies following exposure to optical defocus. The results of the two experiments may be explained by the unmasking of low contrast, high spatial frequency information via a two-stage process: (1) the pattern of relative channel outputs is maintained during optical defocus by the depression of mid-range spatial frequency channels; (2) channel outputs are pooled prior to the production of the final percept. The second set of experiments also provided some evidence of inter-ocular transfer, indicating that the adaptation process is occurring at binocular sites in the cortex.
有大量轶事报道称，在一段时间不进行屈光矫正后近视患者的视力有所改善。我们探究了这种效应是由于对模糊的耐受性增加，还是反映了视力的真正改善。我们的结果清楚地表明，在长时间暴露于光学散焦后，检测和识别字母的能力有显著提高。我们确保没有发生眼部变化，因此这种现象必定是由于对散焦状况的神经补偿。第二组实验测量了对比敏感度，发现暴露于光学散焦后对中等范围（5 - 25周/度）空间频率的敏感度降低。这两个实验的结果可以通过一个两阶段过程来解释，即通过揭示低对比度、高空间频率信息：（1）在光学散焦期间，通过降低中等范围空间频率通道来维持相对通道输出的模式；（2）在产生最终感知之前对通道输出进行汇总。第二组实验还提供了一些双眼间转移的证据，表明适应过程发生在皮质的双眼部位。
