NICU, Ospedale Maggiore Policlinico, Mangiagalli and Regina Elena, IRCCS, University of Milan, Milan, Italy.
Early Hum Dev. 2010 Jul;86 Suppl 1:73-5. doi: 10.1016/j.earlhumdev.2010.01.010. Epub 2010 Feb 13.
The presence of abnormal visual function has been related to overt lesions in the thalami, peritrigonal white matter (such as cavitational-necrotic periventricular leucomalacia) and optic radiations, and also to the extent of occipital cortex involvement. The normal development of visual function seems to depend on the integrity of a network that includes not only optic radiations and the primary visual cortex but also other cortical and subcortical areas, such as the frontal or temporal lobes or basal ganglia, which have been found to play a topical role in the development of vision. Therefore, the complex functions and functional connectivity of the developing brain of premature infants can be studied only with highly sophisticated techniques such as diffusion tensor tractography. The combined use of visual tests and neonatal structural and functional neuroimaging, which have become available for newborn infants, provides a better understanding of the correlation between structure and function from early life. This appears to be particularly relevant considering the essential role of early visual function in cognitive development. The identification of early visual impairment is also important, as it allows for early enrolment in intervention programmes. The association of clinical and functional studies to newer imaging techniques, which are being increasingly used also in neonates, are likely to provide further information on early aspects of vision and the mechanisms underlying brain plasticity, which are still not fully understood. Early exposure to a difficult postnatal environment together with early and unexpected removal from a protective milieu are exclusive and peculiar factors of prematurity that interfere with the normal development of the visual system in pre-term babies. The problem is further compounded by the influence of different perinatal brain lesions affecting the developing brain of premature babies. Nevertheless, in the last few decades, there have been considerable advances in our understanding of the development of vision in pre-term infants during early infancy. This has mainly been due to the development of age-specific tests assessing various aspects of visual function, from ophthalmological examination to more cortical aspects of vision, such as the ability to process orientation or different aspects of visual attention [1-7]. Improvements in understanding very early and specific neurological impairments in neurological functions have been reported in pre-term infants, known to be at risk of developing visual and visual-perceptual impairment. These impairments are due not only to retinopathy, a common finding in premature infants, but also to cerebral (central) visual impairment, secondary to brain lesions affecting the central visual pathway.
异常视觉功能的存在与丘脑、围脑室白质（如囊性坏死性脑室周围脑白质软化）和视辐射的明显病变有关，也与枕叶皮质受累的程度有关。视觉功能的正常发育似乎取决于一个网络的完整性，这个网络不仅包括视辐射和初级视觉皮层，还包括其他皮质和皮质下区域，如额叶或颞叶或基底节，这些区域在视觉发育中起着重要作用。因此，早产儿大脑发育的复杂功能和功能连接只能通过扩散张量轨迹等复杂技术来研究。视觉测试与新生儿结构和功能神经影像学的联合应用，这些技术已可用于新生儿，为从早期生命开始理解结构与功能之间的相关性提供了更好的认识。考虑到早期视觉功能在认知发育中的重要作用，这一点似乎尤为重要。早期发现视觉障碍也很重要，因为这可以让患儿尽早参加干预计划。将临床和功能研究与越来越多地用于新生儿的新型成像技术相结合，可能会提供更多关于早期视觉和大脑可塑性机制的信息，这些机制仍未完全了解。早期暴露于困难的产后环境以及早期且意外地从保护环境中移除，是早产儿特有的独特因素，会干扰早产儿视觉系统的正常发育。不同的围产期脑损伤对早产儿发育中的大脑的影响使问题更加复杂。然而，在过去几十年中，我们对早产儿在婴儿早期视觉发育的理解有了相当大的进展。这主要是由于开发了特定年龄的测试，评估了从眼科检查到更皮质的视觉方面的各种视觉功能，例如处理方向或不同视觉注意力方面的能力[1-7]。据报道，在早产儿中，神经功能的早期和特定的神经损伤方面的理解有所提高，这些早产儿有发生视觉和视觉感知障碍的风险。这些损伤不仅是由于早产儿常见的视网膜病变，还由于影响中央视觉通路的脑损伤导致的中枢性视觉障碍。
