Effects of Raised Intraocular Pressure on Optic Nerve Head Circulation in New Zealand White Rabbit-Laser Doppler Flowmetry Study

眼壓對紐西蘭白兔視神經盤血流之影響－雷射都卜勒血流計實驗

周秉義(Ping-I Chou) ； 李驊(Hwa Lee)

《中華民國眼科醫學會雜誌》 35卷2期 (1996/06) Pp. 161-166

https://doi.org/10.30048/ACTASOS.199606.0006

摘要

目的：雷射都卜勒血流計為一種測量血液流速、體積和血流量的方法。本研究藉雷射都卜勒血流計測量眼壓改變對於紐西蘭白兔視神經盤血流之影響，並證實自主調節的存在。
方法：本研究以十隻紐西蘭白兔為實驗對象。在全身麻醉下，以立體固定儀固定頭部。於動靜脈插管，眼內插管以後，同步測量血壓，眼壓及肛溫。眼壓經由針筒幫浦(syringe pump, Orion 341B)控制，每10mmHg調升／降一次。經由雷射都卜勒血流儀(Perimed PF3)測量眼壓改變對於視神經盤血流量及體積之影響。雷射光照射在視神經盤不同的部位，並避開較大的血管。
結果：當雷射光照射在視神經盤綠，且灌注壓在53.1mmHg(42.7-57.7mmHg)以上時，血流量維持不變，而體積則隨灌注壓下降而下降。當灌注壓小於53.1mmHg時，血流量及體積均隨灌注壓下降而減少。此一結果顯示，眼壓對於視神經盤有重要影響，且在某一特定壓力以內，視神經盤血流有自主調節作用的存在。本研究模式之建立，有助於探討青光眼的病理機轉，並可更進一步研究藥物，腦壓等因素對視神經盤血流的作用。

並列摘要

Purpose: To evaluate the effect of intraocular pressure on optic nerve head (ONH) blood flow and demonstrate the existence of an autoregulatory response of the ONH circulation.
Methods: Ten rabbits weighing 2.0-3.0 Kg were used. Under general anesthesia, each rabbit was fixed on the stereotactic table. Blood pressure, rectal temperature, and intraocular pressure (IOP) were monitored continuously. The IOP was controlled by a syringe pump and increased gradually in a stepwise pattern (10 mmHg in each scale). By means of a laser Doppler blood flowmetry (Perimed PF3), the blood cell flux (F), and concentration of moving blood cells (CMBC) were recorded simultaneously. The laser beam was focused on the inner disc margin away from major vessels when the fundus was observed by indirect ophthalmoscopy.
Results: When the perfusion pressure (PP) was higher than a critical pressure (42.7-55.7 mmHg, mean 53.1 mmHg), F was maintained at a constant level at which time CMBC decreased in proportion to PP. When the PP decreased to the critical pressure, F and CMBC dropped linearly with PP. This phenomenon demonstrated the autoregulatory ability of the ONH that existed only within limited perfusion pressure range under a critical IOP.

並列關鍵字

Optic nerve ； laser Doppler flowmetry ； intraocular pressure