脳回転状網脈絡膜萎縮の1例

A case of gyrate atrophy of the choroid and retina

　41歳女性の左眼に消毒液が入って受診した。両眼とも-8Dの近視であり，矯正視力は右0.4，左0.5であった。両眼眼底に典型的な脳回転状網脈絡膜萎縮の所見があった。両眼に視野狭窄があり，網膜電図は記録不能であった。血清中のオルニチン値は597.3nmol／mlと高値であり，脳回転状網脈絡膜萎縮の診断が確定した。1日量180mgのピリドキシン（ビタミンB₆）の投与を開始し，10週後の血清オルニチン値は455.5nmol／mlになり，約24％低下した。初診から14か月の経過観察で，視力，眼底所見，視野には変化がない。本症はオルニチンアミノトランスフェラーゼ欠損が原因であり，その補酵素であるピリドキシンの大量投与が病変の進行を阻止する可能性がある。

A 41-year-old female sought medical advice after her left eye was accidentally splashed by disinfectivesolution. She had myopia of -8D diopters in either eye. Her corrected visual acuity was 0.4 right and 0.5 left.Funduscopy showed typical findings of gyrate atrophy. Visual field constriction was present in both eyes.Electroretinogram was nonrecordable. Laboratory tests showed elevated serum value of ornithine at 597.3 nmol/mland led to the diangosis of gyrate atrophy. She was given peroral pyridoxine hydrochloride (vitamin B₆) at thedaily dosis of 180 mg/day. Her ornithine level decreased by 24% to 455.5 nmol/ml 10 weeks later. There hasbeen no changes in visual acuity, funduscopic findings, or visual field during the follow-up for 14 months. Thereis a possibility that systemic pyridoxine hydrochloride, which is a co-enzyme of ornithine aminotransferase, mayprevent progression of gyrate atrophy when given at a massive dosis.