Limiting Factors on Spatial Vision in Central Vision Loss

描述(申请人提供)：丧失中心视力的人经常发现很难使用他们残留的周边视力来执行视觉任务。中枢性视力丧失的主要原因是老年性黄斑变性(AMD)，这也是60岁以上人群视力受损和失明的主要原因。随着中心性视力丧失的开始，大多数患者在受影响的黄斑区外形成偏心的视网膜位置，这是首选的视网膜位置(PRL)，作为他们视觉任务的新参考。本项目的长期目标是了解PRL的发展机制(S)，并了解PRL(S)对各种视觉任务的限制因素和潜力，从而为AMD和其他黄斑疾病患者开发有效的视力康复策略。提出的研究项目的第一个目标是评估关于PRL位置的选择是基于优化视觉性能的假设。我们将在中心视力丧失的观察者和视力正常的观察者身上测量一组视觉任务的表现，以构建我们任务的“表现图”。我们将使用这些性能图来预测特定于给定盲点的PRL的位置，这将为我们的任务提供最佳性能。该研究项目的第二个目的是检验一种假设，即外周阅读迟缓是由于外周无法利用文本线索，如冗余和单词的旁中央凹预览。一系列实验将在视力正常的观察者和中心视力丧失的观察者身上进行测试，以评估不同文本线索在单独和不同组合下对阅读的好处。提出的研究项目的第三个目标是测试中央视力丧失者的视觉表现可以从知觉学习中受益的假设。我们将比较几个选定的训练任务的有效性，以确定在改善中心性视力丧失患者的功能视力方面最有效的一项。我们还将比较其他未训练任务在训练前后的表现，以确定学习效果的泛化程度。最后但并非最不重要的一点是，我们将在培训后评估学习效果的持久性。这些目标的发现都有可能发展成为一种有用的康复工具，既可以帮助我们为新近发病的中枢性视力丧失患者确定PRL的最佳位置，也可以改善中枢性视力丧失患者的功能性视力或阅读能力。 公共卫生相关性：随着黄斑区视力的丧失，大多数患有黄斑疾病(如老年性黄斑变性)的人会将黄斑区外的视网膜区域作为他们的“新中心凹”。这个项目的长期目标是了解“新中心凹”是如何发展的，并了解限制因素和改善黄斑疾病患者视力的潜力。

DESCRIPTION (provided by applicant): People who lose their central vision often found it difficult to perform visual tasks using their residual peripheral vision. The leading cause of central vision loss is age-related macular degeneration (AMD), which is also the leading cause of visual impairment and blindness for people over 60 years of age. Following the onset of the central vision loss, most patients develop an eccentric retinal location outside the affected macular area, the preferred retinal locus (PRL), as their new reference for visual tasks. The long-term goals of this project are to understand the mechanism(s) underlying the development of the PRL, and to understand the limiting factors and potentialities of the PRL(s) for various visual tasks so that effective visual rehabilitative strategies may be developed for patients with AMD and other macular disorders. The first aim of the proposed research project is to evaluate the hypothesis that the selection of the location for a PRL is based on optimizing visual performance. We will measure performance for a set of visual tasks in observers with central vision loss and observers with normal vision to construct "performance maps" for our tasks. We will use these performance maps to predict the location for a PRL, specific to a given scotoma, which offers the best performance for our tasks. The second aim of the proposed research project is to test the hypothesis that slow peripheral reading is due to an inability of the periphery to take advantage of text cues such as redundancy and parafoveal preview of words. A series of experiments, to be tested in observers with normal vision and observers with central vision loss, will evaluate the benefit on reading offered by different text cues in isolation and in various combinations. The third aim of the proposed research project is to test the hypothesis that visual performance for people with central vision loss can benefit from perceptual learning. We will compare the effectiveness of a few selected training tasks to determine the one that is most effective in improving functional vision of people with central vision loss. We will also compare performance for other untrained tasks before and after training to determine how generalizable the learning effect is. Last but not the least; we will evaluate the longevity of the learning effect following training. The findings from each of these aims have the potential of developing into a useful rehabilitative tool that can either help us identify the best location for a PRL for patients with recent onset central vision loss, or to improve the functional vision or reading performance in patients with central vision loss. PUBLIC HEALTH RELEVANCE: Following the loss of vision in the macular area, most people with macular disorders such as age-related macular degeneration adopt a retinal region outside the macular area as their "new fovea". The long-term goals of this project are to understand how the "new fovea" develops, and to understand the limiting factors and the potential for improving vision for people with macular disorders.