片眼性から両眼性に移行したBasedow眼症の1例

Involvement of the contralateral eye in a case of unilateral Graves ophthalmopathy

要約　背景：片眼性のBasedow眼症は約10％の症例に起こるとされ，発症時期が左右眼で異なる場合がある。目的：内科治療が行われているにもかかわらず，片眼性から両眼性に進行したBasedow眼症の症例の報告。症例：32歳女性が数週間前からの左眼の瞼裂拡大で受診した。所見と経過：右眼に－6D，左眼に－5.5Dの近視があり，矯正視力は左右眼とも1.2であった。眼球突出度は右16mm，左18mmで，瞼裂高は右9mm，左11mmであった。血液検査で甲状腺機能亢進の所見があり，磁気共鳴画像検査（MRI）で左眼の上直筋と上眼瞼挙筋の肥大があった。7か月後に右眼の上眼瞼の後退と下転障害が起こり，MRIで上眼瞼挙筋の肥大があった。球後への放射線照射は奏効せず，ボツリヌス毒素の注射の効果は一過性であった。初診から20か月後に両眼の上眼瞼挙筋の延長術を行い，眼瞼後退は軽症化し，下転障害は残った。結論：片眼に発症したBasedow眼症が両眼性に移行することがあり，注意が必要である。

Abstract.　Background：Graves ophthalmopathy has been reported to occur unilaterally in about 10％ of cases. It may also involve one eye only and become bilateral later. Purpose：To report a case of Graves ophthalmopathy that involved one eye initially and that became bilateral later. Case：A 32-year-old woman presented with enlarged lid aperture in her left eye since one month before. Findings and Clinical Course：Both eyes were myopic at about －6 diopters. Corrected visual acuity was 1.2 in either eye. Hertel exophthalmometer showed protrusion by 16 mm right and 18 mm left. Lid aperture was 9 mm right and 11 mm left. Blood examinations showed findings of hyperthyroidism. Magnetic resonance imaging（MRI）showed hypertrophy of superior rectus and levator muscles in the left eye. The right eye developed upper eyelid retraction and restricted downgaze 7 months later. MRI showed hypertrophy of levator muscle. Radiation of retrobulbar tissue was futile. Eyelid retraction improved following bilateral extension of levator muscle 20 months after her initial visit. Conclusion：This case illustrates that Graves ophthalmopathy may involve one eye only to become bilateral later.