Table_2_Retinal and Optic Nerve Integrity Following Monocular Inactivation for the Treatment of Amblyopia.docx

In animal models, monocular deprivation (MD) by lid closure mimics the effects of unilateral amblyopia in humans. Temporary inactivation of one or both eyes with intraocular administration of tetrodotoxin (TTX) has recently been shown to promote recovery from the anatomical effects of MD at post-critical period ages when standard recovery strategies fail. In the current study, the retinae and optic nerves of animals subjected to 10 days of monocular retinal inactivation were assessed for pathological changes as a means of assessing the viability of this potential new amblyopia therapy. Retinal sections from both eyes were subjected to hematoxylin and eosin staining and were then examined for cell density and soma size in the ganglion cell layer (GCL). Sections of the optic nerve from each eye were examined for neurofilament protein, myelin, glial cell density, and glial fibrillary acidic protein (GFAP). Our study revealed no evidence of gross histopathological abnormalities following inactivation for 10 days, nor was there evidence of degeneration of axons or loss of myelin in the optic nerve serving inactivated eyes. On all measurements, the inactivated eye was indistinguishable from the fellow eye, and both were comparable to normal controls. We confirmed that our inactivation protocol obliterated visually-evoked potentials for 10 consecutive days, but visual responses were restored to normal after the effects of inactivation wore off. Notwithstanding the critical need for further assessment of ocular and retinal health following inactivation, these results provide evidence that retinal inactivation as a treatment for amblyopia does not produce significant retinal damage or degeneration.

在动物模型中，通过眼睑缝合构建的单眼剥夺（monocular deprivation, MD）模型可模拟人类单侧弱视的病变效应。近期研究表明，在标准康复策略失效的关键期后年龄段，采用河豚毒素（tetrodotoxin, TTX）眼内给药对单眼或双眼进行暂时性失活，可促进单眼剥夺所引发的解剖结构损伤的康复。本研究针对接受10天单眼视网膜失活处理的动物，对其视网膜与视神经的病理变化进行评估，以此验证该新型弱视潜在疗法的可行性。具体而言，对双眼的视网膜切片进行苏木精-伊红染色，随后检测神经节细胞层（ganglion cell layer, GCL）的细胞密度与胞体大小；对每只眼的视神经切片分别检测神经丝蛋白、髓鞘、神经胶质细胞密度以及胶质纤维酸性蛋白（glial fibrillary acidic protein, GFAP）的表达情况。研究结果显示，经10天失活处理后，未观察到明显的大体组织病理学异常，失活眼的视神经亦未出现轴突退变或髓鞘丢失现象。各项检测指标均显示，失活眼与对侧正常眼无显著差异，且二者与正常对照组的结果一致。本研究证实，该失活方案可连续10天消除视觉诱发电位，但在失活效应消退后，视觉反应可恢复至正常水平。尽管仍需进一步评估失活处理后眼部与视网膜的健康状况，但本研究结果表明，作为弱视治疗手段的视网膜失活疗法，并不会引发显著的视网膜损伤或退行性病变。