線維柱帯切除術後の視神経乳頭血流波形と構造変化の関連

Changes in optic disc structure and blood flow waveform following trabeculectomy

要約　目的：開放隅角緑内障における線維柱帯切除術（TLE）前後の視神経乳頭血流波形と構造変化の関連を検討した。

対象と方法：術後3か月の時点で，眼圧下降率20％以上の28例28眼を対象とした。術前および術後3か月にスペクトラルドメイン光干渉断層計を用いてブルッフ膜開口端から内境界膜までの最小リム幅（BMO-MRW），乳頭周囲網膜神経線維層厚（RNFLT）を，レーザースペックルフローグラフィを用いて視神経乳頭血流の組織領域（MBR_T）と血流波形を測定した。術前後の変化はウィルコクソンの符号付順位検定，BMO-MRW，RNFLTと血流，血流波形の関連は重回帰分析にて検討した。

結果：眼圧下降に伴い眼軸長は有意に減少し，眼灌流圧は有意に増加した（すべてp＜0.05）。BMO-MRWは有意に増加した（p＝0.001）がRNFLTは変化を認めなかった（p＝0.294）。MBR_Tは有意な変化はなく，血流波形のfluctuation（p＝0.020），flow acceleration index（FAI）（p＝0.002）は有意に減少した。重回帰分析ではBMO-MRW変化率に対しresistivity index変化率が（p＝0.045），RNFLT変化率に対しFAI変化率が有意な因子となった（p＝0.037）。

結論：TLE術前後で視神経乳頭血流波形と構造は関連を認めた。

Abstract　Purpose：To investigate the association between the changes of structure and blood flow waveform in optic nerve head（ONH）before and after trabeculectomy（TLE）in open-angle glaucoma.

Methods：A total of 28 eyes of 28 patients achieved a ≥20％ reduction in IOP at three months after TLE were included. We measured Bruch's membrane opening minimum rim width（BMO-MRW）and retinal nerve fiber layer thickness（RNFLT）using SD-OCT, the mean blur rate in tissue area（MBR_T）as a relative measure of the blood flow and blood flow waveforms in optic nerve head using LSFG before surgery and 3 months postoperatively. Wilcoxon's signed-rank test was used to analyze the differences in these parameters before and after TLE. Linear and multiple regression analyses were used to determine factors related to the rates of change in the BMO-MRW and RNFLT.

Results：Axial length decreased and ocular perfusion pressure increased significantly at 3 months after TLE（p＜0.05）. BMO-MRW increased significantly（p＝0.001）, but RNFLT did not change（p＝0.294）. There was no significant change in MBR_T. In blood flow waveforms, fluctuation and flow acceleration index（FAI）decreased（p＝0.020 and p＝0.002, respectively）after TLE. In multiple regression analyses, the rate of change in resistivity index was a significantly related factor to that of BMO-MRW（β＝0.382, p＝0.045）, and the rate of change in FAI was a significant related factor to that of RNFLT（β＝0.396, p＝0.037）.

Conclusions：There was an association between the changes of structure and blood flow waveform in ONH before and after TLE.