網膜細動脈瘤破裂に伴う黄斑円孔の発症機序を術中所見から推察できた1例

Mechanism of macular hole formation after ruptured retinal macroaneurysm revealed by surgical findings

要約　目的：手術所見から網膜細動脈瘤破裂に伴う黄斑円孔の発症機序の一因を考察する。

症例：67歳女性，主訴は突然の右眼視力低下。

所見：初診時視力は右眼（0.15），左眼（0.8），眼圧は右眼20mmHg，左眼21mmHgであった。前眼部所見は両眼軽度白内障を認め，眼底所見では右眼黄斑部に網膜細動脈瘤破裂による内境界膜下出血，網膜下出血を認めた。高血圧を認めたため，内科で入院加療後，発症2週後に水晶体再建術および27G硝子体手術を行った。内境界膜剝離を行い，内境界膜下出血を除去，中心窩に器質化した血塊を認めたため硝子体剪刀で切除した。網膜細動脈瘤から連続的に網膜下さらには小さな黄斑円孔に通じる白色索状物を認めた。20％SF₆ガス置換し，24時間の腹臥位とした。術後，黄斑円孔は閉鎖し，右眼視力は（0.8）に改善した。

結論：本症例では網膜細動脈瘤から網膜下出血を生じ，網膜下圧上昇から，中心窩に黄斑円孔が形成されたと考えられた。

Abstract　Purpose：Based on surgical findings, we considered the possible causes of the macular hole formation associated with ruptured retinal macroaneurysm.

Case：A 67-year-old female had experienced sudden visual deterioration in her right eye. Corrected visual acuity was 0.15 for the right and 0.8 for the left eye. Intraocular pressure was 20 mmHg in the right and 21 mmHg in the left eye. Mild cataract was noted. Sub-inner limiting membrane（ILM）hemorrhage and subretinal hemorrhage caused by retinal macroaneurysm rupture was noted in her right eye. Hypertension was recognized, and surgery was therefore planned after blood pressure control.

　A 27-gauge vitrectomy was performed 2 weeks after the onset. ILM peeling was performed, and the sub-ILM hemorrhage was removed. Formation of a whitened blood clot in the fovea was observed, indicating the existence of macular hole formation. The blood clot was excised with a vitreous scissor. A whitened subretinal strand continuing from the retinal macroaneurysm to the macular hole was also observed. Finally, SF₆ gas was injected, and the patient was placed in the prone position for 24 hours. The macular hole was closed and visual acuity improved to 0.8 six weeks later.

Conclusion：Based on intraoperative findings, we speculated that retinal macroaneurysm rupture had raised subretinal pressure due to subretinal hemorrhage and pushed the fovea forward resulting in macular hole formation.