Functional Mechanisms of Neural Control in Convergence Insufficiency

描述(申请人提供)：会聚功能不全(CI)是一种在成人和儿童中普遍存在的双眼视觉障碍，其特征是近视比远视更大，融合会聚幅度降低，会聚点附近后退，调节会聚/调节比率(AC/A)降低。CI的症状包括复视/视力模糊，在阅读或在附近工作时感到眼睛疲劳和头痛，从而干扰日常生活活动。最近的NEI/NIH多中心随机临床试验，融合功能不全治疗试验(CITT)，证实了基于办公室的矫正和调节治疗与家庭强化(OBVAT)对CI的有效性，报告称73%的患者视觉功能和症状持续改善。我们的团队首次发表了脑梗塞患者在OBVAT前后使用会聚眼球运动诱发的fMRI神经基质数据。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、顶叶后皮质和小脑疣的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)减少近距离外斜视的数量。5我们当前建议的目的是测试以下两个假设作为CI的潜在潜在机制，这些机制在OBVAT后可能会得到改善：1)通过融合的“慢”部分在近空间和远空间适应融合的能力降低；2)通过融合的“快”成分快速减小视差误差的能力降低。我们的定量方法与已建立的CITT标准相结合，不仅将解决有关导致CI的潜在机制的重要问题，我们的提案还将寻求确定经过验证的融合疗法如何补救症状。我们的建议将通过量化以下两种潜在机制中的任何一种来确定是否引起CI：1)屈光适应的速率和幅度，2)强迫聚焦注视视差曲线，3)眼球运动的峰值收敛速度(研究视觉线索，如视差、调节和近端刺激的分离和组合)，以及4)OBVAT前后快、慢聚焦神经底物的功能活动。集合起来的研究团队在OBVAT、收敛不足、验光、视觉科学、眼球运动研究、功能成像、建模和统计学方面尤其精通，并拥有成功完成本研究的两个目标所需的资源。我们项目目标的结果可以导致具有更高成功率的定向治疗，潜在地减少补救症状的时间，并最终降低医疗成本。

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.