ビタミンA欠乏症の治療後にinterdigitation zoneが回復した1例

A case of vitamin A deficiency with recovered interdigitation zone by optical coherence tomography

要約　目的：ビタミンA欠乏症により夜盲を生じ，治療後に夜盲が改善してinterdigitation zone（IZ）が回復した1例の報告。

症例：42歳女性，夜盲を主訴に受診した。幼少期から肝機能障害があり，2年前には，肝硬変と診断された。

所見と経過：矯正視力は右1.5，左1.5。光干渉断層計（OCT）では網膜厚の減少とIZの消失，網膜電図（ERG）では振幅の減弱が認められた。血清ビタミンA濃度は5IU/dl未満で，ビタミンA欠乏による夜盲と診断した。ビタミンAを投与し，3日後には自覚症状が軽快し，ERGも振幅が改善した。治療開始後からOCTで中心窩網膜厚が増加し，IZも中心窩から周辺に向けて徐々に回復がみられた。

結論：OCTによる網膜厚とIZの経時的な変化が，治療効果の評価に有用であった。

Abstract　Purpose: To report a case who developed vitamin A deficiency with night blindness and who showed recovery of interdigitation zone by optical coherence tomography（OCT）.

Case: A 42-year-old woman presented with night blindness of gradual onset. She had liver dysfunction since childhood. She was diagnosed with liver cirrhosis 2 years before.

Findings: Corrected visual acuity was 1.5 in either eye. OCT showed decreased retinal thickness and absence of interdigitation zone. Electroretinogram showed decreased amplitude. Vitamin A in the serum was below 5 IU/dl. These findings led to the diagnosis of vitamin A deficiency. Night blindness disappeared after 3 days of peroral vitamin A at the daily dosis of 5,000 IU. Electroretinogram showed improvement and retinal thickness at the fovea increased. Interdigitation zone gradually recovered from the fovea towards the periphery.

Conclusion: Changes in retinal thickness and interdigitation zone were useful in the diagnosis and treatment of vitamin A deficiency.