線維柱帯切除術による眼圧変化と視神経乳頭周囲の網膜視神経線維層微小循環の変化

Changes in intraocular pressure and microcirculation in the nerve fiber layer in the peripapillary retina following trabeculectomy

要約　目的：線維柱帯切除術による眼圧変化が視神経乳頭周囲の網膜視神経線維層（RNFL）の微小循環に与える影響を検討する。

対象と方法：原眼科病院で線維柱帯切除術を行った41眼で，年齢は70.0±10.1歳。視神経乳頭周囲のRNFL内微小循環は，ZEISS社のCirrus-HD OCTのAngioplex for ONHで測定したcapillary perfusion値（P値，毛細血管密度）とcapillary flux index値（F値，血管血流速度）（ともに上方，耳側，下方，鼻側，INDEX）を使用し，術前1か月以内と術後2週間前後の各値を対応のあるt検定で比較した。また，術前と術後の耳側のP値とF値の変化量を多変量解析した。いずれも有意水準をp＜0.05とした。

結果：術前の平均眼圧は21.8mmHg，術後は12.3mmHgであった。P値は耳側が41.4±2.8％から42.9±3.8％，P INDEXが37.8±2.7％から38.5±2.6％と有意に上昇していた。F値は耳側が0.32±0.043から0.301±0.040，下方が0.312±0.039から0.298±0.038，鼻側が0.318±0.044から0.302±0.040，F INDEXが0.316±0.040から0.300±0.037と有意に減少していた。術前と術後の耳側のP値とF値の変化量を多変量解析した結果，P値，F値の変化量と眼圧差との有意な相関はなく，F値の変化量は術前F値が高いほど減少していた。

結論：線維柱帯切除術後の眼圧下降により，P値は増加しF値は低下する傾向があった。P値，F値の変化量は眼圧変化と相関せず，一時的な眼圧の急激な変化には強く影響されないことが示された。術前F値が高いほどF値の変化量は減少していたが，眼圧下降により血管面積が増え，それに伴いF値が減り，血流量全体としては術前後で大きく変化してない可能性がある。

Abstract　Objective：To investigate the effects of intraocular pressure changes due to trabeculectomy on microcirculation of the retina nerve fiber layer（RNFL）around the optic disc.

Subjects and Methods：This study was made 41 eyes who underwent trabeculectomy at Hara Eye Hospital and were 70.0±10.1 years old. Microcirculation in the RNFL around the optic disc was measured by Capillary Perfusion value（P value）and Capillary Flux Index value（F value）（both upper, temporal, lower, nasal side and INDEX）measured by ZEISS Cirrus-HD OCT Angioplex for ONH. The values within one month before the operation and around two weeks after the operation were compared by a paired t-test. The amount of change in the P value and F value on the temporal side before and after the operation was multivariately analyzed. In each case, the significance level was p＜0.05.

Results：The mean intraocular pressure before surgery was 21.8 mmHg, and after surgery 12.3 mmHg. The P value increased significantly from 41.4±2.8％ to 42.9±3.8％ on the temporal side, and P INDEX increased from 37.8±2.7％ to 38.5±2.6％. The F value decreased significantly from 0.320±0.043 to 0.301±0.040 on the temporal side, from 0.312±0.039 to 0.298±0.038 on the lower side, from 0.318±0.044 to 0.302±0.040 on the nasal side, and from 0.316±0.040 to 0.300±0.037 on F INDEX. As a result of multivariate analysis of the change in P value and F value on the temporal side before and after surgery, the change in P value and F value did not show a significant correlation with the intraocular pressure difference, and the change in F value decreased as the preoperative F value increased.

Conclusion：P value tended to increase and F value tended to decrease due to a decrease in intraocular pressure after trabeculectomy. The changes in P and F values did not correlate with changes in intraocular pressure, suggesting that they were not strongly affected by temporary rapid changes in intraocular pressure. The higher the preoperative F value, the smaller the change in F value. It is considered that the blood vessel area increased due to the decrease in intraocular pressure, and the F value decreased accordingly. It was suggested that the blood flow did not change significantly before and after the operation.