著明な視力改善が得られた強度近視眼の大型黄斑円孔の1例

A case of significant visual improvement in a highly myopic eye with a large macular hole

要約　目的：強度近視眼の大型黄斑円孔（MH）に対して硝子体手術を施行し，著明な視力改善が得られた症例の報告。

症例：71歳の女性が両眼の成熟白内障のため紹介され大阪労災病院を受診した。白内障術前は眼底透見不能で，白内障術後の右矯正視力は0.4であった。

所見：右眼は眼内レンズ挿入眼で，眼軸長は27.4mmであり，光干渉断層計（OCT）で最小円孔径763μmの大型MHを認めた。また，OCT機器の内部固視灯を固視するように指示すると，傍中心窩の網膜前膜（ERM）を伴った領域が撮像された。初回硝子体手術で内境界膜を翻転しMH内へ埋入することでMHは閉鎖し，術後3か月で右矯正視力1.0に改善した。しかし，中心窩の網膜外層構造は回復不良で，術後マイクロペリメータ検査では中心窩の視感度は0dBであった。同検査で測定された固視点は中心窩から約1°離れており，術前OCT検査で内部固視灯固視時に撮像された領域と一致した。同領域は術後OCT検査でERMの除去と網膜形態の改善が確認された。術後2年現在，視力・固視点ともに不変である。

結論：本症例は術前より約1°の偏心固視が確立していたが，同部位の網膜形態が改善したことで著明な視力改善が得られたと考えられた。

Abstract　Purpose：To report the case of a patient with significant visual improvement in a highly myopic eye with a large macular hole（MH）treated by vitrectomy.

Case：A 71-year-old female was referred to our hospital because of bilateral mature cataract. Before cataract surgery, the fundi were not visible. After cataract surgery, her corrected visual acuity in the right eye was 0.4.

Findings：The axial length of the right eye with the intraocular lens was 27.4 mm, and optical coherence tomography（OCT）showed a large MH with a minimum hole diameter of 763 μm. She was instructed to maintain ocular fixation on the internal fixation light of the OCT device and the parafoveal region associated with epiretinal membrane（ERM）was imaged. In the first vitrectomy, the internal limiting membrane was inverted and implanted into the MH to close it, and her corrected visual acuity improved to 1.0 3 months postoperatively. However, the retinal outer layer structure in the fovea was still poorly restored, and postoperative microperimeter showed a foveal sensitivity of 0 dB. The fixation point measured by postoperative microperimeter was approximately 1 degree away from the fovea, which was consistent with that preoperatively imaged with OCT. Furthermore, postoperative OCT confirmed the removal of ERM and improvement in retinal morphology in this region. Two years after this vitrectomy, her visual acuity and fixation point remained unchanged.

Conclusion：In this case report, we consider that approximately 1 degree of eccentric fixation had already been established preoperatively, and the restored retinal morphology resulted in the significant improvement in visual acuity.