深部強調光干渉断層計検査で篩状板の亀裂を観察した後天性視神経乳頭ピットの2症例

Two cases of acquired pit of the optic nerve with defects of lamina cribrosa observed by enhanced depth imaging optical coherence tomograph

要約　目的：後天性視神経乳頭ピット（APON）を伴う緑内障眼において，深部強調光干渉断層計画像（EDI-OCT）にてAPONに一致した篩状板の亀裂を観察した2症例の報告。症例：77歳および69歳の男性。緑内障が疑われ精査したところ，視神経乳頭の耳下側辺縁に半月状の急峻な陥凹を伴うAPONが認められ，その部分のリム狭小化と網膜神経線維層の菲薄化がみられた。EDI-OCTにて視神経乳頭深部の断層検査を施行したところ，APONの部分の篩状板に楔状の亀裂が認められた。Humphrey視野検査では，APONとリム狭小化に一致した上方の緑内障性視野障害を認めた。結論：APON部分の篩状板には亀裂があり，この部位の軸索障害が視野欠損の原因である可能性がある。

Abstract.　Purpose：To report 2 glaucoma cases which presented defects of lamina cribrosa corresponding to the acquired pit of the optic nerve（APON）by enhanced depth imaging optical coherence tomograph（EDI-OCT）. Cases：Patients were 77 and 69 year-old males who were suspected for glaucoma. Fundus examination revealed steep crescent-shaped deepening in the infero-temporal sector of the optic nerve accompanied by narrowing of the rim and thinning of the retinal nerve fiber layer. Deep optic nerve structure examination with EDI-OCT showed a defect in the lamina cribrosa corresponding to the APON. Humphrey visual field test showed glaucomatous superior visual field defect caused by APON and the narrowing of the rim. Conclusion：A defect of lamina cribrosa was detected at the region of APON. The insult to axons passing through this part of lamina cribroa could be the cause the visual field defect.