Cocker K D, Moseley M J, Stirling H F, Fielder A R
Imperial College School of Medicine, London, UK.
Dev Med Child Neurol. 1998 Mar;40(3):160-2. doi: 10.1111/j.1469-8749.1998.tb15440.x.
Vision in very early infancy is probably subserved by subcortical pathways, with many cortical processes only fully emerging by 3 months of age. The improvement of vision in delayed visual maturation (DVM) occurs around this time, and this has given rise to the suggestion that the condition may have a subcortical basis that resolves with the appearance of cortical function. To explore further the role of cortical and subcortical visual systems in DVM we studied the visual development in identical twins, one of whom had type 1b DVM. Two non-invasive methods of investigating visual pathway function were employed: the acuity card procedure (a behavioural response) and luminance and grating pupillometry. While the former reflects both subcortical and cortical function and can be detected at birth, pupil responses to gratings reflect cortical activity alone and normally become measurable at 1 month of age. Development of both behavioural and pupillary responses was delayed in DVM, indicating that although the underlying defect is primarily subcortical, secondarily it delays the emergence of cortically mediated responses. The observed rapidity of improvement--over a very few days and within a narrow age range--suggests a discrete rather than a widespread structural abnormality, the improvement of which is closely linked to postmenstrual age.
婴儿早期的视觉可能由皮层下通路支持，许多皮层过程直到3个月大时才完全显现。延迟性视觉成熟（DVM）中视力的改善大约在这个时候出现，这引发了一种观点，即这种情况可能有一个皮层下基础，随着皮层功能的出现而得到解决。为了进一步探究皮层和皮层下视觉系统在DVM中的作用，我们研究了同卵双胞胎的视觉发育情况，其中一人患有1b型DVM。我们采用了两种非侵入性方法来研究视觉通路功能：视力卡片程序（一种行为反应）以及亮度和光栅瞳孔测量法。虽然前者反映皮层下和皮层功能，且在出生时就能检测到，但瞳孔对光栅的反应仅反映皮层活动，通常在1个月大时才能测量到。DVM中行为和瞳孔反应的发育均延迟，这表明尽管潜在缺陷主要是皮层下的，但其次也会延迟皮层介导反应的出现。观察到的改善速度——在短短几天内且在狭窄的年龄范围内——表明存在一种离散而非广泛的结构异常，其改善与孕龄密切相关。
