Ashtari Manzar, Cyckowski Laura, Yazdi Alborz, Viands Amanda, Marshall Kathleen, Bókkon István, Maguire Albert, Bennett Jean
Department of Radiology, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, United States of America.
Center for Cellular and Molecular Therapeutics, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, United States of America.
PLoS One. 2014 Jan 21;9(1):e86068. doi: 10.1371/journal.pone.0086068. eCollection 2014.
A phenomenon characterized by the experience of seeing light without any light actually entering the eye is called phosphenes or photopsias. Phosphenes can occur spontaneously or via induction by external stimuli. Previous reports regarding phosphenes have primarily focused on externally induced phosphenes such as by applying alternating or direct current to the cortex. A few of these reports used functional magnetic resonance (fMRI) to study activations induced by cortical phosphenes. However, there are no fMRI reports on spontaneous phosphenes originating from the retina and the resulting pattern of cortical activations. We performed fMRI during a reversing checkerboard paradigm in three LCA patients who underwent unilateral gene therapy and reported experiencing frequent phosphene on a daily basis. We observed bilateral cortical activation covering the entire visual cortices when patients reported experiencing phosphenes. In contrast, in the absence of phosphenes, activation was regulated by patient's visual ability and demonstrated improved cortical activation due to gene therapy. These fMRI results illustrate the potential impact of phosphene perception on visual function and they may explain some of the variability that clinicians find in visual function testing in retinal degeneration. Although we did not perform correlations between visual function and phosphenes, we hope data presented here raises awareness of this phenomenon and its potential effect on visual function and the implications for clinical testing. We recommend a thorough history for phosphene experiences be taken in patients with retinal disease who are candidates for gene or molecular therapy. Lastly, these data illustrate the potential power of fMRI as an outcome measure of gene therapy and the negative impact phosphenes may have on vision testing. fMRI has proven to be a sensitive, non-invasive, and reproducible test paradigm for these purposes and can complement standard visual function testing.
一种以在没有任何光线实际进入眼睛的情况下却能体验到看见光为特征的现象被称为光幻视或光幻觉。光幻视可自发出现，也可由外部刺激诱发。先前关于光幻视的报告主要集中在外部诱发的光幻视，比如通过向皮层施加交流电或直流电。其中一些报告使用功能磁共振成像（fMRI）来研究皮层光幻视诱发的激活情况。然而，尚无关于源自视网膜的自发光幻视及其导致的皮层激活模式的fMRI报告。我们在三名接受单侧基因治疗且每天都频繁经历光幻视的莱伯先天性黑蒙（LCA）患者进行棋盘格反转范式时进行了fMRI检查。当患者报告经历光幻视时，我们观察到双侧皮层激活覆盖了整个视觉皮层。相比之下，在没有光幻视的情况下，激活受患者视觉能力的调节，并显示出由于基因治疗而改善的皮层激活。这些fMRI结果说明了光幻视感知对视觉功能的潜在影响，并且它们可能解释了临床医生在视网膜变性的视觉功能测试中发现的一些变异性。尽管我们没有对视觉功能和光幻视进行相关性分析，但我们希望这里呈现的数据能提高对这种现象及其对视觉功能的潜在影响以及对临床测试的意义的认识。我们建议对可能接受基因或分子治疗的视网膜疾病患者进行关于光幻视经历的详尽病史询问。最后，这些数据说明了fMRI作为基因治疗结果测量指标的潜在作用以及光幻视可能对视力测试产生的负面影响。事实证明，fMRI对于这些目的而言是一种敏感、非侵入性且可重复的测试范式，并且可以补充标准的视觉功能测试。
