Tarita-Nistor Luminita, González Esther G, Markowitz Samuel N, Steinbach Martin J
Vision Science Research Program, Toronto Western Research Institute, Toronto, Ontario, Canada.
Vis Neurosci. 2009 Nov;26(5-6):487-94. doi: 10.1017/S0952523809990265. Epub 2009 Dec 11.
The aim of this study was to explore the plasticity of fixation in patients with central vision loss. Most of these patients use preferred retinal loci (PRLs) in the healthy eccentric part of the retina to fixate, but fixation stability and retinal location are not always optimal for best visual performance. This study examined whether fixation stability and a new PRL location can be trained and whether these changes in ocular motor control transfer into better reading performance. Six patients with age-related macular degeneration participated in the study. Fixation stability measurements, microperimetry, and auditory biofeedback training were performed with the MP-1 microperimeter. The auditory biofeedback was used during five 1-h long training sessions to improve fixation and relocate the PRL. Fixation location and stability were recorded while viewing four different targets: a cross, a letter, a word, and a nine-cycle radial grating. Visual acuity was assessed with the Early Treatment Diabetic Retinopathy Study (ETDRS) chart and reading performance with the MNRead test. The results showed that all patients developed a new PRL in an optimal location for reading, and they were able to use it consistently while viewing different targets. Fixation stability improved 53% after training. Learning transferred to the old PRL even though fixation stability at this location was not trained. All these improvements in ocular motor control translated into better reading performance: reading speed improved 38% and reading acuity and critical print size gained two lines. We conclude that the ability of the ocular motor system to fixate is flexible in patients with central vision loss: a new PRL can be trained, fixation stability can be improved, and learning transfers to an untrained location. These gains in ocular motor control result in better visual performance. This property can be successfully used to optimize the residual vision of patients with central vision loss.
本研究的目的是探讨中心视力丧失患者注视的可塑性。这些患者中的大多数在视网膜健康的偏心部位使用首选视网膜位点（PRL）进行注视，但注视稳定性和视网膜位置并不总是对最佳视觉表现而言是最优的。本研究检查了注视稳定性和新的PRL位置是否可以训练，以及这些眼动控制的变化是否能转化为更好的阅读表现。六名年龄相关性黄斑变性患者参与了本研究。使用MP - 1显微视野计进行注视稳定性测量、微视野检查和听觉生物反馈训练。在五个1小时的训练课程中使用听觉生物反馈来改善注视并重新定位PRL。在观看四个不同目标时记录注视位置和稳定性：一个十字、一个字母、一个单词和一个九周期径向光栅。使用早期糖尿病视网膜病变研究（ETDRS）视力表评估视力，使用MNRead测试评估阅读表现。结果表明，所有患者都在阅读的最佳位置形成了一个新的PRL，并且他们在观看不同目标时能够持续使用它。训练后注视稳定性提高了53%。学习转移到了旧的PRL，尽管该位置的注视稳定性未经过训练。眼动控制的所有这些改善都转化为了更好的阅读表现：阅读速度提高了38%，阅读视力和临界印刷字体大小提高了两行。我们得出结论，中心视力丧失患者的眼动系统的注视能力是灵活的：可以训练一个新的PRL，提高注视稳定性，并且学习可以转移到未训练的位置。眼动控制的这些改善导致了更好的视觉表现。这一特性可以成功用于优化中心视力丧失患者的残余视力。
