Karyotakis Nikolaos G, Ginis Harilaos S, Dastiridou Anna I, Tsilimbaris Miltiadis K, Pallikaris Ioannis G
Medical School, Institute of Vision and Optics, University of Crete, Heraklion, Greece.
Opththalmology Department, University Hospital of Larissa, Larissa, Greece.
Acta Ophthalmol. 2015 Aug;93(5):e343-e348. doi: 10.1111/aos.12652. Epub 2015 Feb 1.
The intraocular pressure (IOP) is determined by a dynamic equilibrium between the production and outflow of the aqueous humour. The relationship between IOP and the outflow rate through the conventional and unconventional pathway is quantified by the outflow facility coefficient (C). The purpose of this study is to employ a direct (manometric) tonographic technique and determine C as well as its inverse, resistance (R), as a function of IOP in the living human eye.
Nineteen cataract patients were enrolled in the study. An intraoperative manometric device was used to measure IOP. After cannulation of the anterior chamber, the IOP was increased by infusion of controlled amounts of saline solution. At 40 mmHg, the infusion stopped, and a pressure sensor recorded the IOP. The measured pressure-volume relationship was considered in order to convert pressure changes to corresponding ocular volume changes. An appropriate mathematical model was applied to calculate C and (its inverse), R.
The average C was 0.0672 ± 0.0296 μl/min/mmHg at 40 mmHg and 0.2652 ± 0.1164 μl/min/mmHg at 20 mmHg. There was a strong dependence of coefficient C on IOP in all subjects (p < 0.001). The corresponding values for R were 17.9 ± 11.17 min mmHg/μl at 40 mmHg and 4.51 ± 2.69 min mmHg/μl at 20 mmHg.
This study provides measurement of outflow facility and its dependence with pressure in healthy living human eyes. This relation is shown to be non-linear, using a direct manometric method.
眼内压（IOP）由房水生成与流出之间的动态平衡决定。通过传统和非传统途径的流出率与IOP之间的关系由流出系数（C）量化。本研究的目的是采用直接（测压）眼压描记技术，确定活体人眼中C及其倒数阻力（R）作为IOP的函数。
19例白内障患者纳入本研究。术中使用测压装置测量IOP。在前房插管后，通过输注控制量的盐溶液来升高IOP。在40 mmHg时停止输注，压力传感器记录IOP。考虑测量的压力-容积关系，以便将压力变化转换为相应的眼容积变化。应用适当的数学模型计算C及其倒数R。
在40 mmHg时，平均C为0.0672±0.0296 μl/min/mmHg，在20 mmHg时为0.2652±0.1164 μl/min/mmHg。在所有受试者中，系数C对IOP有很强的依赖性（p<0.001）。R在40 mmHg时的相应值为17.9±11.17 min mmHg/μl，在20 mmHg时为4.51±2.69 min mmHg/μl。
本研究提供了健康活体人眼中流出系数及其与压力依赖性的测量。使用直接测压法表明这种关系是非线性的。
