Visual function and adaptation across the lifespan

人类在日常生活活动中严重依赖视觉功能，而大脑的很大一部分专门用于视觉功能。因此，视力障碍是最令人恐惧的残疾之一也就不足为奇了。幸运的是，眼睛和视觉系统似乎能够适应各种环境影响，从而有可能有利地改变结果，从而预防或减少视力损害。实际上，每一种视觉功能指标都有一个发展期，发展期达到最大值，随后进入老年。然而，在视觉功能的许多方面，人们对其发展和衰退的认识并不清楚。例如，许多减缓近视进展的预防性疗法已经被探索，但没有成功，这反映了屈光发展的基本机制仍然未知的事实。我在这一领域的工作旨在了解这些机制，这是人们可以合理地期望制定预防或逆转策略之前的必要步骤。我参与其中的一个突破是发现眼睛的长度会随着焦点的变化而变化。这意味着我们应该能够通过控制眼睛的焦点来控制眼睛的生长，但我们仍然不知道眼睛是如何知道是变大还是变小的。该提议的一部分是在动物模型中测试三种可能的眼睛光学生长信号对镜片的反应，这些镜片要么使眼睛变长，要么使眼睛变短。通常，在研究视觉功能时，儿童和老年人被忽视了，与年轻人相比，可能是因为很难做。这个提议的一个主要部分是调查整个人类寿命范围内的视觉功能。具体来说，该计划是对这个年龄段的大量个体进行眼睛大小、形状、焦点、协调和运动的测量，对所有个体使用类似的方法。通过这种方式，我们可以研究各种因素如何相互作用，以及这些因素如何随着年龄的增长而变化。增加我们对这些过程的理解应该会导致优化发展和减少或补偿衰退的战略。这其中的含义是重要的。例如，眼睛协调能力的发展会影响儿童的学习能力，而立体感的丧失会增加老年人摔倒的风险，从而危及他们的独立性，甚至危及他们的生命。最后，视觉的各个方面不仅不是相互独立的；他们还会受到注意力和情境等因素的影响。这里，儿童和老年人没有得到很好的研究，他们的行为似乎与年轻人不同。通过对不同类型的目标进行眼动测量，并给参与者不同的指示，我们将确定他们快速准确反应能力的年龄相关差异。了解与年龄相关的正常值是很重要的，因为注意力和/或抑制对眼球运动的影响可能会影响疾病的诊断（如阿尔茨海默病、精神分裂症、多动症）。

Human beings rely heavily on visual function for activities of daily living and large portions of the brain are dedicated to visual function. It is therefore not surprising that visual impairment is one of the most highly feared disabilities. Fortunately, the eyes and visual system appear to be capable of adaptation to a variety of environmental influences opening the possibility of favorably altering outcomes, thus preventing or reducing visual impairment. Virtually every metric of visual function has a period of development to a maximum which subsequently declines into old age. However, for many aspects of visual function the development and decline are not well understood. For example, many preventative therapies for slowing the progression of myopia have been explored without success, reflecting the fact that the basic mechanisms which underlie refractive development are still unknown. My work in this area is aimed at understanding these mechanisms, a necessary step before one can reasonably expect to develop strategies for prevention or reversal. One of the breakthroughs of which I have been a part was the discovery that eyes grow in length to match their point of focus. This means that we should be able to control eye growth by controlling the focus of the eye, but we still don’t know how the eye knows whether to grow larger or smaller. Part of this proposal is to test, in an animal model, how three possible optical eye growth signals respond to lenses which either make the eye grow longer or shorter. Typically, children and the elderly have been neglected, in comparison to young adults, when investigating visual function, probably because it is difficult to do. A major portion of this proposal is to investigate visual functions across the range of the human lifespan. In particular, the plan is to take measurements of eye size, shape, focus, coordination and movement for a large number of individuals over this age range, using similar methods for all individuals. In this way we can study how the various factors interact and how this changes with age. Increasing our understanding of these processes should lead to strategies for optimizing development and reducing or compensating for decline. The implications of this are significant. For example, the development of eye coordination impacts learning in children and the loss of stereopsis puts the elderly at increased risk of falling which in turn puts their independence, if not their lives, at risk. Finally, not only are the various aspects of vision not independent of each other; they are also affected by such things as attention and the context of the situation. Here again children and the elderly are not as well studied and appear to behave differently than young adults. Using eye movement measurements to different types of targets and giving participants different instructions we will determine age related differences in their ability to quickly and accurately respond. It is important that age related normal values are known since the influence of attention and/or inhibition on eye movements may affect how diseases are diagnosed (e.g. Alzheimer’s disease, schizophrenia, ADHD).