Optic perineuritis (OPN) is a rare inflammatory disorder in which the inflammation is confined to optic nerve sheath. It can be idiopathic or secondary to underlying systemic autoimmune disorder. It usually presents with unilateral progressive diminution of vision with pain on eye movements and optic disc oedema. Hence, clinically OPN mimics optic neuritis resulting in delayed diagnosis and suboptimal treatment. In contrast to optic neuritis, patients with OPN are usually of older age group and more likely show sparing of central vision. MRI is an important tool for diagnosis of OPN apart from optic nerve sheath biopsy. Perineural enhancement on MRI is diagnostic of OPN. Oral corticosteroid therapy gives dramatic and rapid improvement in signs and symptoms. Rapid tapering of steroids increases the risk of relapse. Overall, prognosis of OPN is generally good if adequate treatment is given timely.

中文翻译：

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视神经炎

视神经膜炎（OPN）是一种罕见的炎症性疾病，其中炎症仅限于视神经鞘膜。它可以是特发性的，也可以继发于潜在的全身性自身免疫性疾病。它通常表现为单侧视力逐渐减弱，伴有眼球运动和视盘水肿疼痛。因此，临床OPN模仿视神经炎，导致诊断延迟和治疗效果欠佳。与视神经炎相反，OPN患者通常年龄较大，并且更可能显示中央视力不佳。除了视神经鞘活检，MRI是诊断OPN的重要工具。MRI的神经周围增强可诊断OPN。口服皮质类固醇激素疗法可显着，快速地改善体征和症状。类固醇的快速变细会增加复发的风险。全面的，