Limiting Factors on Spatial Vision in Central Vision Loss

描述（由申请人提供）：丧失中央视觉的人通常发现难以使用其残余周边视觉执行视觉任务。中心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。随着中心视力丧失的发作，大多数患者在受影响的黄斑区域（优选视网膜位点（PRL））之外形成偏心视网膜位置，作为他们视觉任务的新参考。该项目的长期目标是了解PRL发展的潜在机制，并了解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。 拟议的研究项目的第一个目的是评估的假设，PRL的位置的选择是基于优化视觉性能。我们将测量一组视觉任务的表现，在观察员与中央视力损失和观察员与正常视力，以构建“性能地图”为我们的任务。我们将使用这些性能图来预测特定于给定暗点的PRL的位置，这为我们的任务提供了最佳性能。 拟议的研究项目的第二个目的是要测试的假设，即缓慢的周边阅读是由于无法利用的周边文字线索，如冗余和旁视预览的话。一系列的实验，将在具有正常视力的观察者和具有中心视力丧失的观察者中进行测试，将评估不同文本线索单独和以各种组合提供的阅读的益处。 拟议研究项目的第三个目的是检验中心视力丧失的人的视觉表现可以从感知学习中受益的假设。我们将比较几个选定的训练任务的有效性，以确定一个是最有效的改善中央视力丧失的人的功能性视力。我们还将比较训练前后其他未经训练的任务的表现，以确定学习效果的可推广性。最后但并非最不重要的是，我们将评估培训后学习效果的持久性。 这些目标的发现都有可能发展成为一种有用的康复工具，可以帮助我们为近期发作的中心视力丧失患者确定PRL的最佳位置，或者改善中心视力丧失患者的功能性视力或阅读表现。

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.