Functional Mechanisms of Neural Control in Convergence Insufficiency

描述（由申请人提供）：会聚功能不全（CI）是成人和儿童中普遍存在的双眼视觉障碍，其特征在于在近处比在远处更大的外隐斜视、融合会聚幅度降低、近会聚点后退和调节会聚比（AC/A）降低。当从事阅读或其他近距离工作时，CI与包括复视/视力模糊、眼疲劳和头痛的症状相关，从而干扰日常生活活动。最近的NEI/NIH多中心随机临床试验，会聚不足治疗试验（CITT），证明了基于视觉的会聚和家庭强化治疗（OBVAT）对CI的有效性，报告73%的患者视觉功能和症状持续改善。我们的团队发表了第一个功能磁共振成像神经基板数据诱发前，然后后OBVAT的CI患者会聚眼球运动。我们的结果支持随着视觉症状的减轻，观察到以下情况：1）额眼区、后顶叶皮层和小脑蚓部中功能活动的信号变化百分比增加，2）会聚峰值速度增加，3）会聚近点减少，4）正融合幅度增加，和5）外隐斜视的量在近5处减少。我们当前提议的目的是测试以下两个假设，作为可能在OBVAT后得到改善的CI的潜在机制：1）通过聚散度的“慢”分量在近空间和远空间中适应聚散度的能力降低，以及2）通过聚散度的“快速”分量快速减小视差误差的能力降低。我们的定量方法不仅与既定的CITT标准相结合，解决了有关导致CI的潜在机制的重要问题，我们的建议旨在确定一种有效的聚散疗法如何治疗症状。我们的建议将通过量化以下内容来确定这两种潜在机制中的任何一种是否会导致CI：1）隐斜视适应的速率和幅度，2）强迫性聚散注视视差曲线，3）会聚眼运动的峰值速度（研究视觉线索，如视差，调节和近端刺激的隔离和组合），和4）在OBVAT之前和之后的快和慢聚散神经基质的功能活性。集合的研究团队在OBVAT、会聚不足、验光、视觉科学、眼科研究、功能成像、建模和统计学方面知识渊博，拥有成功完成本研究两个目标所需的资源。我们项目目标的结果可以导致有针对性的治疗，提高成功率，可能减少症状补救的时间，并最终降低医疗保健成本。

DESCRIPTION (provided by applicant): Convergence insufficiency (CI), a prevalent binocular vision disorder in adults and children, is characterized by greater exophoria at near than at distance, reduced fusional convergence amplitude, receded near point of convergence, and a reduced accommodative convergence over accommodation ratio (AC/A). CI is associated with symptoms that include double/blurred vision, eyestrain, and headaches when engaged in reading or other near work, thus interfering with activities of daily living. The recent NEI/NIH multi-center randomized clinical trial, the Convergence Insufficiency Treatment Trial (CITT), demonstrated the effectiveness of Office-Based Vergence and Accommodative Therapy with home reinforcement (OBVAT) for CI, reporting 73% of patients have sustained improvements of vision function and symptoms. Our team published the first fMRI neural substrate data evoked using convergence eye movements in CI patients before and then post- OBVAT. Our results support that with the reduction of visual symptoms, the following were observed: 1) an increase in the percent signal change of functional activity in the frontal eye fields, posterior parietal cortex and the cerebellar vermis, 2) an increase in convergence peak velocity, 3) a decrease in the near point of convergence, 4) an increase in positive fusional amplitude, and 5) a reduction in the amount of exophoria at near.5 The aims of our current proposal are to test the following two hypotheses as potential underlying mechanisms of CI that may be improved post OBVAT: 1) a reduced ability to adapt vergence in near and far space via the 'slow' component of vergence and 2) a reduced ability to quickly diminish disparity error via the 'fast' component of vergence. Not only will our quantitative methods integrated with established CITT standards address important questions about potential mechanisms causing CI, our proposal seeks to identify how a validated vergence therapy may remediate symptoms. Our proposal will determine whether either of these two potential mechanisms are causing CI by quantifying the following: 1) rate and magnitude of phoria adaptation, 2) forced vergence fixation disparity curves, 3) peak velocity of convergence eye movements (studying visual cues such as disparity, accommodation and proximal stimuli in isolation and combination), and 4) the functional activity of the fast and slow vergence neural substrates prior to, and then after, OBVAT. The assembled study team is particularly knowledgeable in terms of OBVAT, convergence insufficiency, optometry, vision science, oculomotor research, functional imaging, modeling and statistics with the necessary resources to successfully complete both aims of this study. Results from our project's aims can lead to targeted treatments with improved success rates, potentially reducing the time to remediate symptoms, and ultimately reducing health care costs.