Baseler Heidi A, Gouws André, Crossland Michael D, Leung Carmen, Tufail Adnan, Rubin Gary S, Morland Antony B
York Neuroimaging Centre, Department of Psychology, University of York, York, UK.
Optom Vis Sci. 2011 Oct;88(10):1255-61. doi: 10.1097/OPX.0b013e3182282f13.
To assess cortical responses in patients undergoing antiangiogenic treatment for wet age-related macular degeneration (AMD) using functional magnetic resonance imaging (fMRI) as an objective, fixation-independent measure of topographic visual function.
A patient with bilateral neovascular AMD was scanned using fMRI before and at regular intervals while undergoing treatment with intravitreal antiangiogenic injections (ranibizumab). Blood oxygenation level-dependent signals were measured in the brain while the patient viewed a stimulus consisting of a full-field flickering (6 Hz) white light alternating with a uniform gray background (18 s on and 18 s off). Topographic distribution and magnitude of activation in visual cortex were compared longitudinally throughout the treatment period (<1 year) and with control patients not currently undergoing treatment. Clinical behavioral tests were also administered, including visual acuity, microperimetry, and reading skills.
The area of visual cortex activated increased significantly after the first treatment to include more posterior cortex that normally receives inputs from lesioned parts of the retina. Subsequent treatments yielded no significant further increase in activation area. Behavioral measures all generally showed an improvement with treatment but did not always parallel one another. The untreated control patient showed a consistent lack of significant response in the cortex representing retinal lesions.
Retinal treatments may not only improve vision but also result in a concomitant improvement in fixation stability. Current clinical behavioral measures (e.g., acuity and perimetry) are largely dependent on fixation stability and therefore cannot separate improvements of visual function from fixation improvements. fMRI, which provides an objective and sensitive measure of visual function independent of fixation, reveals a significant increase in visual cortical responses in patients with wet AMD after treatment with antiangiogenic injections. Despite recent evidence that visual cortex degenerates subsequent to retinal lesions, our results indicate that it can remain responsive as its inputs are restored.
使用功能磁共振成像（fMRI）作为一种客观的、与注视无关的地形视觉功能测量方法，评估接受抗血管生成治疗的湿性年龄相关性黄斑变性（AMD）患者的皮质反应。
一名双侧新生血管性AMD患者在接受玻璃体内抗血管生成注射（雷珠单抗）治疗前及定期进行fMRI扫描。在患者观看由全场闪烁（6Hz）白光与均匀灰色背景交替组成的刺激（开18秒，关18秒）时，测量大脑中的血氧水平依赖信号。在整个治疗期（<1年）纵向比较视觉皮质激活的地形分布和幅度，并与未接受治疗的对照患者进行比较。还进行了临床行为测试，包括视力、微视野检查和阅读技能测试。
首次治疗后，视觉皮质激活区域显著增加，包括更多通常从视网膜病变部位接收输入的后皮质。后续治疗未使激活区域进一步显著增加。行为测量结果总体上均显示治疗后有所改善，但并不总是相互平行。未经治疗的对照患者在代表视网膜病变的皮质中始终缺乏显著反应。
视网膜治疗不仅可以改善视力，还可能同时改善注视稳定性。目前的临床行为测量方法（如视力和视野检查）在很大程度上依赖于注视稳定性，因此无法将视觉功能的改善与注视改善区分开来。fMRI提供了一种独立于注视的客观且敏感的视觉功能测量方法，显示抗血管生成注射治疗后湿性AMD患者的视觉皮质反应显著增加。尽管最近有证据表明视网膜病变后视觉皮质会退化，但我们的结果表明，随着输入的恢复，它仍能保持反应性。
