Limiting Factors on Spatial Vision in Central Vision Loss

描述（由申请人提供）：失去中心视觉的人经常发现很难用他们剩余的周边视觉来执行视觉任务。中央性视力丧失的主要原因是年龄相关性黄斑变性（AMD），这也是60岁以上人群视力受损和失明的主要原因。中枢性视力丧失后，大多数患者在受影响的黄斑区域外出现偏心性视网膜位置，即首选视网膜位置（PRL），作为其视觉任务的新参考。本项目的长期目标是了解PRL发展的机制，了解PRL在各种视觉任务中的限制因素和潜力，以便为AMD和其他黄斑疾病患者制定有效的视觉康复策略。该研究项目的第一个目的是评估一个假设，即PRL的位置选择是基于优化视觉表现。我们将测量中央视力丧失的观察者和视力正常的观察者在一系列视觉任务中的表现，为我们的任务构建“性能图”。我们将使用这些性能映射来预测PRL的位置，特定于给定的暗点，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验证一个假设，即外围阅读缓慢是由于外围无法利用文本线索，如冗余和单词的旁中央预览。一系列实验将在视力正常的观察者和中央视力丧失的观察者中进行测试，以评估不同文本提示单独和不同组合对阅读的好处。该研究项目的第三个目的是测试一个假设，即中央视力丧失的人的视觉表现可以从知觉学习中受益。我们将比较几个选定的训练任务的有效性，以确定在改善中央视力丧失患者的功能性视力方面最有效的训练任务。我们还将比较训练前后其他未训练任务的表现，以确定学习效果的泛化程度。最后但并非最不重要的；我们将在培训后评估学习效果的持续时间。这些目标的发现都有可能发展成为一种有用的康复工具，可以帮助我们为最近出现的中央视力丧失的患者确定PRL的最佳位置，或者改善中央视力丧失患者的功能视力或阅读能力。

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.