The most common visual defect to follow a lesion of the retrochiasmal pathways is homonymous hemianopia (HH), whereby patients are blind to the contralesional visual field of each eye. Homonymous hemianopia has been studied in terms of its deleterious consequences on perceptual, cognitive and motortasks as well as because it represents an interesting model of vision loss after a unilateral lesion of the occipital lobe. From a behavioral perspective, in addition to exhibiting a severe deficit in their contralesional visual field, HH patients can also exhibit dissociations between perception and awareness. Firstly, HH patients suffering from anosognosia may be unaware of their visual field defect. Secondly, HH patients can present with unconscious visual abilities in the blind hemifield, a phenomenon referred to as blindsight. Thirdly, recent reports demonstrate that HH patients can suffer from a subtle deficit in their ipsilesional visual field that they are unaware of, a condition called sightblindness (i.e. the reverse case of ‘blindsight’). Finally, HH patients may also exhibit visual hallucinations in their blind field; however, such patients are not systematically aware that their perceptions are unreal. In this review, we provide an overview of the visual-field losses in HH patients after a left or right unilateral occipital lesion. Furthermore, we explore the implications of these four phenomena for models of visual processing and rehabilitation of visual field defects in HH patients. Finally, in contrast to the traditional view that HH is solely a visual-field defect, we discuss why this deficit is an interesting model for studying the dissociation between perception and awareness.

中文翻译：

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偏盲中知觉与意识的分离。

跟随视交叉后通路病变的最常见的视觉缺陷是同向偏盲（HH），即患者对每只眼睛的对侧视野是失明的。同名偏盲已在其对知觉、认知和运动任务的有害后果方面进行了研究，并且因为它代表了枕叶单侧病变后视力丧失的有趣模型。从行为的角度来看，除了表现出对侧视野的严重缺陷外，HH 患者还可以表现出感知和意识之间的分离。首先，患有失认症的 HH 患者可能不知道他们的视野缺损。其次，HH 患者可以在盲区出现无意识的视觉能力，这种现象称为盲视。第三，最近的报告表明，HH 患者的同侧视野可能会出现他们不知道的细微缺陷，这种情况称为视盲（即“盲视”的相反情况）。最后，HH 患者也可能在他们的盲区表现出幻视；然而，这些患者并没有系统地意识到他们的感知是不真实的。在这篇综述中，我们概述了左侧或右侧单侧枕骨病变后 HH 患者的视野损失。此外，我们探讨了这四种现象对 HH 患者视觉处理和视野缺损康复模型的影响。最后，与传统的 HH 只是视野缺陷的观点相反，