角膜穿孔を生じたビタミンA欠乏による角膜軟化症の1例

A case of corneal perforation caused by keratomalacia due to vitamin A deficiency

要約　目的：自閉スペクトラム症に伴う摂食障害によるビタミンA欠乏が原因の角膜軟化症・角膜穿孔の症例を経験したので報告する。

症例：13歳，男児。両眼の結膜充血，眼をよく擦るため近医で抗菌薬や副腎皮質ステロイドなどの点眼・軟膏治療を受けたが改善しなかった。同時期より栄養不良を疑われており，精査のため広島市民病院を紹介された。発達障害により視力検査は測定不能であった。両眼角膜上皮障害と右眼角膜穿孔を認め，採血でビタミンAは5IU/dL未満（基準値：27.2〜102.7），レチノール結合蛋白は0.3mg/dL（基準値2.7〜6.0）であり，右眼ビタミンA欠乏性角膜軟化症と診断した。点眼・軟膏は右眼のみ継続とし，ビタミン剤の全身投与を開始したところ角膜上皮障害は改善した。ビタミン剤の全身投与開始1か月後，血中レチノール結合蛋白は3.4mg/dLに改善した。しかし，左眼に角膜潰瘍を発症したため点眼・軟膏を投与したところ，発症1か月後には改善した。

結論：角膜軟化症は日本国内では非常に稀であるが，偏食や摂食障害により発症する可能性がある。進行すると不可逆的な視機能障害をきたすため注意が必要である。

Abstract　Purpose：We report a case of keratomalacia and corneal perforation caused by vitamin A deficiency due to a feeding disorder associated with autism spectrum disorder and pervasive developmental disorder.

Case：The patient was a 13-year-old boy with bilateral conjunctival hyperemia rubbed his eyes frequently. He was treated with antibacterial drugs, corticosteroids, and ointments by a local ophthalmologist. However, his condition did not improve, and on suspecting malnutrition, he was referred to Hiroshima City Hiroshima Citizens Hospital. Due to the presence of a developmental disorder, the patient's vision could not be assessed. Corneal epithelial lesions in both eyes and corneal perforation in the right eye were observed. Blood samples showed a vitamin A level of less than 5 IU/dL（reference value 27.2-102.7 IU/dL）and a retinol-binding protein level of 0.3 mg/dL（reference value 2.7-6.0 mg/dL）, leading to a diagnosis of vitamin A deficiency keratomalacia in the right eye. Eye drops and ointment were continued only in the right eye and systemic administration of vitamins was started. The corneal epithelial damage improved. One month after systemic administration of vitamins, the blood retinol-binding protein level improved to 3.4 mg/dL. The patient developed a corneal ulcer in the left eye and was treated with ophthalmic drops and ointments. The corneal ulceration improved one month later.

Conclusion：Although keratomalacia is very rare in Japan, it can occur due to picky eating or feeding disorders. It is important to note that the progression of the disease can lead to irreversible visual dysfunction.