部分的に著しい低形成を認めた片眼性視神経低形成の1例

A case of unilateral optic nerve hypoplasia with marked involvement of orbital portion

要約　目的：中枢神経系に異常のない片眼性視神経低形成の症例の報告。症例：正常産で出生し，神経または身体的な発達異常のない4歳男児が右眼の外斜視で受診した。所見：裸眼視力は右光覚なし，左0.9で，右眼にdouble ring signを伴わない視神経乳頭の低形成があった。磁気共鳴画像検査（MRI）では，右側の視神経低形成があり，眼窩部で特に顕著であった。中枢神経系には異常所見はなく，透明中隔も正常であった。結論：視神経低形成では，眼窩内で特に顕著な部分的低形成を示すことがある。

Abstract.　Purpose：To report a case of unilateral optic nerve hypoplasia with marked involvement in the orbital portion and with no abnormalities in the central nervous system. Case：A 4-year-old boy presented with exotropia in his right eye. He had been born full term. He showed apparently no developmental anomaly somatically or mentally. Findings：Uncorrected visual acuity was no light perception in the right eye and 0.9 in the left. The right eye showed hypoplasia without double ring sign. Magnetic resonance imaging showed hypoplasia of right optic nerve that was more marked in the orbital portion. There was no abnormal finding regarding the central nervous system or septum pellucidum. Conclusion：This case illustrates that optic nerve hypoplasia may manifest more markedly in the orbital portion.