Functional Mechanisms of Neural Control in Convergence Insufficiency

描述（由申请人提供）：会聚不全（CI）是一种普遍存在于成人和儿童的双眼视力障碍，其特征是近处的外斜视大于远处，会聚幅度减小，近会聚点减小，调节会聚比（AC/ a）减小。CI与复视/视力模糊、眼疲劳和阅读或其他近距离工作时头痛等症状相关，从而干扰日常生活活动。最近的NEI/NIH多中心随机临床试验，收敛功能不全治疗试验（CITT），证明了基于办公室的收敛和调节治疗与家庭强化（OBVAT）对CI的有效性，报告73%的患者视力功能和症状持续改善。我们的团队发表了首个用会聚眼动诱发的功能磁共振成像神经基质数据，这些数据分别发生在颅脑损伤患者术前和术后。我们的研究结果支持，随着视觉症状的减轻，观察到以下现象：1)额叶视野、后顶叶皮层和小脑蚓部功能活动的信号变化百分比增加，2)收敛峰速度增加，3)收敛点附近减少，4)正融合幅度增加，5)近我们当前提案的目的是测试以下两个假设，作为可能在OBVAT后得到改进的CI的潜在潜在机制：1)通过收敛的“慢”分量降低了在近空间和远空间中适应收敛的能力；2)通过收敛的“快”分量降低了快速减少视差误差的能力。我们的定量方法不仅将与已建立的CITT标准相结合，解决有关导致CI的潜在机制的重要问题，而且我们的建议旨在确定经过验证的收敛疗法如何补救症状。我们的建议将通过以下量化来确定这两种潜在机制是否导致CI: 1)视距适应的速率和幅度，2)强制聚焦点注视视差曲线，3)会聚眼运动的峰值速度（研究视差、调节和近端刺激等视觉线索的单独和组合），以及4)在OBVAT之前和之后的快速和慢速收敛神经底物的功能活动。组建的研究团队在OBVAT、会聚不足、验光、视觉科学、眼动研究、功能成像、建模和统计方面知识特别丰富，并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，可能减少治疗症状的时间，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.