25ゲージ硝子体手術後に鼻側に楔状視野障害を生じた4例

Four cases who showed wedge-shaped visual field defect in the nasal quadrant after 25-gauge vitrectomy

要約　目的：25ゲージシステムによる硝子体手術後に，鼻側に楔状視野障害を生じた4例の報告。

対象と方法：4例の原疾患は黄斑円孔2例，黄斑上膜1例，網膜分離症1例。手術は球後麻酔3例，テノン囊下麻酔1例。全例シャンデリア照明を使用した25ゲージ4ポートで硝子体手術を施行し，内境界膜（ILM）剝離の際にBBGを使用した。黄斑円孔の2例では液空気置換後にSF₆ガスの注入を行った。

結果：4例とも術後早期より鼻側視野障害を訴えた。ゴールドマン視野検査を施行したところ，黄斑を頂点とする鼻側の楔状視野障害を認めた。術後も視野に変化はなかった。OCTアンギオグラフィ検査を行った黄斑円孔症例において，術後に明らかな網膜循環障害を疑う所見はなかった。

結論：視野障害の原因としては，循環障害，ILM剝離の影響，麻酔の影響などが考えられるが，原因を特定することはできなかった。ただし，いずれも鼻側の楔状視野障害であり，何らかの共通の原因が考えられる。

Abstract　Purpose：To report 4 cases who developed wedge-shaped visual field defect in the nasal sector following 25-gauge vitreous surgery.

Cases：The series comprised 2 eyes with macular hole, one eye with epiretinal membrane, and one eye with retinoschisis. Vitreous surgery was performed under retrobulbar anesthesia in 3 cases and subtenon anesthesia in one case. Surgery was performed with 25-gauge four-port system under chandelier illumi-nation in all the cases. Brilliant blue G was used for peeling of inner limiting membrane. Two cases of macular hole received fluid-air exchange and SF₆ gas injection.

Results：All the cases noticed disturbed visual field in the nasal sector immediately after surgery. Goldmann perimetry showed a wedge-shaped field defect in the nasal sector towards the point of fixation. The visual field defect persisted throughout the period of follow-up. One case with macular hole was evaluated by OCT angiography and showed no circulatory disturbance in the retina.

Conclusion：Pathogenesis in visual field defect remains unclear, although there are possibilities of circulatory disorders in the retina or optic nerve, influence of the inner limiting membrane peeling, or side effect of anesthesia. Similarities in the pattern of visual field defect in the 4 eyes seem to indicate that some common causes may be present.