ABSTRACT Individuals with pure alexia often have visual field defects such as right homonymous hemianopia. Relatively few attempts have been made to develop criteria to differentiate pure alexia from hemianopic alexia. In this Commentary we provide concrete suggestions to distinguish the two disorders. We also report on additional assessments with two previously reported cases for whom the diagnosis of pure alexia was called into question and an alternative proposal was offered that the reading deficits were instead due to hemianopia. We show that the results of clinical and neuropsychological tests do not support the account that the reading impairment was caused by the visual field defect. In particular, for both cases, the right homonymous hemianopia was not complete, and a split-field reading task demonstrated an inability also to read words presented in the intact left visual field. In conclusion, pure alexics may indeed show fairly modest word-length effects; however, the presence of right homonymous hemianopia and a non-extreme gradient of reading speed alone are not sufficient grounds to put in doubt the diagnosis. We propose that a fuller clinical and neuropsychological examination taking into account the possible confounding effects of the visual field defects will help to distinguish pure alexia from hemianopic alexia.

中文翻译：

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当轻度单纯性失语症可能无法还原为偏盲性失语症时

摘要 纯失读症患者常有视野缺损，如右眼同向偏盲。相对较少的尝试制定标准来区分纯性失语症和偏盲性失语症。在本评论中，我们提供了区分这两种疾病的具体建议。我们还报告了对先前报告的两个病例的额外评估，这些病例的纯失读症的诊断受到质疑，并提供了替代建议，即阅读障碍是由于偏盲引起的。我们表明，临床和神经心理学测试的结果不支持阅读障碍是由视野缺陷引起的说法。特别是，对于这两种情况，右同向偏盲并不完整，分视野阅读任务也表明无法阅读完整左视野中呈现的单词。总之，纯词法可能确实显示出相当温和的字长效应；然而，仅存在右侧同向偏盲和非极端阅读速度梯度并不足以成为怀疑诊断的理由。我们建议进行更全面的临床和神经心理学检查，同时考虑到视野缺陷的可能混杂影响，将有助于区分单纯性失语症和偏盲性失语症。