College of Biomedical Sciences, Cardiff University, Maindy Road, Cardiff, CF24 4HQ, UK.
Dhahran Eye Specialist Hospital, Dhahran, 7500, Saudi Arabia.
CNS Drugs. 2019 Feb;33(2):161-173. doi: 10.1007/s40263-018-0583-8.
The antiepileptic drug vigabatrin is associated with characteristic visual field loss (VAVFL) and thinning of the peripapillary retinal nerve fibre layer (PPRNFL); however, the relationship is equivocal.
The aim of this study was to determine the function-structure relationship associated with long-term exposure to vigabatrin, thereby improving the risk/benefit analysis of the drug.
A cross-sectional observational design identified 40 adults who had received long-term vigabatrin for refractory seizures, who had no evidence of co-existing retino-geniculo-cortical visual pathway abnormality, and who had undergone a standardized protocol of perimetry and of optical coherence tomography (OCT) of the PPRNFL. Vigabatrin toxicity was defined as the presence of VAVFL. The function-structure relationship for the superior and inferior retinal quadrants was evaluated by two established models applicable to other optic neuropathies.
The function-structure relationship for each model was consistent with an optic neuropathy. PPRNFL thinning, expressed in micrometres, asymptoted at an equivalent visual field loss of worse than approximately - 10.0 dB, thereby preventing assessment of more substantial thinning. Transformation of the outcomes to retinal ganglion cell soma and axon estimates, respectively, resulted in a linear relationship.
Functional and structural abnormality is strongly related in individuals with vigabatrin toxicity and no evidence of visual pathway comorbidity, thereby implicating retinal ganglion cell dysfunction. OCT affords a limited measurement range compared with perimetry: severity cannot be directly assessed when the PPRNFL quadrant thickness is less than approximately 65 µm, depending on the tomographer. This limitation can be overcome by transformation of thickness to remaining axons, an outcome requiring input from perimetry.
抗癫痫药物氨己烯酸与特征性视野丧失（VAVFL）和视乳头神经纤维层（PPRNFL）变薄有关；然而，这种关系是不确定的。
本研究旨在确定与长期暴露于氨己烯酸相关的功能-结构关系，从而改善该药物的风险/获益分析。
采用横断面观察性设计，确定了 40 名接受长期氨己烯酸治疗难治性癫痫的成年人，他们没有证据表明存在共存的视网膜-膝状体-皮质视觉通路异常，并且接受了标准的视野检查和 PPRNFL 的光学相干断层扫描（OCT）。氨己烯酸毒性定义为存在 VAVFL。通过适用于其他视神经病变的两种已建立的模型，评估上、下视网膜象限的功能-结构关系。
每个模型的功能-结构关系都与视神经病变一致。以微米为单位表示的 PPRNFL 变薄在视野损失超过约-10.0dB 时达到渐近线，从而防止了对更严重变薄的评估。将结果转换为视网膜神经节细胞体和轴突的估计值，分别产生了线性关系。
在没有视觉通路合并症的氨己烯酸毒性个体中，功能和结构异常密切相关，从而暗示了视网膜神经节细胞功能障碍。与视野检查相比，OCT 提供的测量范围有限：当 PPRNFL 象限厚度小于约 65µm 时，无法直接评估严重程度，具体取决于断层扫描仪。通过将厚度转换为剩余的轴突，可以克服这一限制，这是一种需要来自视野检查的输入的结果。
