脤絡膜血流循環與近視之關係

Choroidal Blood Flow and Myopia

施永豐(Yung-Feng Shih)

《慈濟醫學雜誌》 5卷4期 (1993/12) Pp. 259-266

https://doi.org/10.6440/TZUCMJ.199312.0259

摘要

脤絡膜血流循環被認為和近視黃斑部網膜退化有關，而且改變脤絡膜血流可能影響眼球之發育生長。我們是以初生小雞為研究對象。我們發現初生即給予眼罩遮蔽，可以引發近視，在14日後可產生近視化眼軸增長，並使脤絡膜循環降低為原來之37%。在如在第12日即拿掉眼罩，則脤絡膜血流變為原來之51%，但近視化眼軸增長並未回復。然後，我們在初生小雞作角膜切開來引發近視，以除去眼罩可能產生的局部溫度改變，那可能影響脤絡膜血流。結果，角膜切開而產生近視之眼球有明顯脤絡膜減少之現象，約為原來之60%，但未產生近視者則無影響。後來，我們切除脤絡膜神經以除去對脤絡膜循環之控制，來減少脤絡膜血流，結果脤絡膜血流降至原來之21%，並使局部之網膜外細胞層產生退化，並使眼球經赤道部徑略小。所以，我們認為脤絡膜血流的降低可能和近視化眼球增長有關，但減少脤絡膜血流反而無法誘使近視化眼球增長，所以脤絡膜血流減少是近視之結果，而非原因。

關鍵字

脤絡膜血流循環 ； 近視黃斑部網膜退化 ； 脤絡膜神經 ； 近視化眼軸增長

並列摘要

Choroidal blood flow (CBF)was suggested to be an important factor in myopic maculopathy, and alterations in CBF also could affect eye growth. We ought to explore the relationship of CBF and myopic ocular growth by using laser Doppler velocimetry and myopic animal model. Study I, we used goggle-induced myopic model to explore this topic. The results were: 1) blood flow in non-goggled chicks was similar in both eyes; 2) blood flow was significantly reduced in the goggled eye in chicks wearing goggles for 14 days- 37% of control; and 3) blood flow was still significantly reduced in the goggled eye in chicks whose goggles were removed two days before measurement- 51% of control. Study II, we used corneal incision-induced ocular enlargement that eliminated the thermal effects observed with goggles to investigate the effects of ocular enlargement on CBF. The results were: 1) ocular enlargement was induced in 11 out of 12 chicks with vertical cuts. The CBF in the operated eye of these 11 animals was 62% of that in the nonoperated eye. 2) ocular enlargement was also induced in 8 of 14 chicks with horizontal cuts. The CBF in the operated eye in these eight chicks was 60% of that in the nonoperated eye. Study III, we examined the effects on eye size of artificially reducing CBF by unilaterally transecting the choroidal nerves of the ciliary ganglion. CBF in birds with choroidal nerve cuts was great reduced in the treated eye (21% of nontreated eye). The treated eyes of these birds showed gross depigmentation and histologically evident loss of outer retina. In choroidal nerve cut group, the ocular size (nasotemporal and dorsoventral) was slightly diminished in treated eyes compared to the sham treated eyes. These results indicate that CBF is reduced as a consequence of ocular enlargement, and large decrease in CBF do not enhance myopic eye growth.

並列關鍵字

choroidal blood flow ； myopic maculopathy ； laser doppler velocimetry ； choroidal nerve ； oclar growth