ARC Center of Excellence in Vision Science, Centre for Ophthalmology and Visual Science, The University of Western Australia, 2 Verdun St, Nedlands, WA, Australia.
Graefes Arch Clin Exp Ophthalmol. 2010 Mar;248(3):401-7. doi: 10.1007/s00417-009-1288-y. Epub 2010 Jan 28.
Ophthalmodynamometric studies can provide useful clinical information regarding glaucoma, cerebrospinal fluid pressure, and vascular disease but are affected by variable reproducibility and unknown calibration of force in terms of intraocular pressure (IOP). The aim of this study was to calculate calibration factors and identify key design principles using three different types of ophthalmodynamometers.
We constructed a modified ophthalmodynamometer named OcuDyn using a large contact lens inside a ring force transducer with continuous signal acquisition and averaging. OcuDyn and Sisler ophthalmodynamometers were applied to isolated pig eyes which were cannulated and connected to a fluid reservoir and a pressure transducer to measure induced IOP at increasing force application. Using these two devices and a Meditron ophthalmodynamometer, we measured the minimum ophthalmodynamometric force (ODF) required to induce pulsation in the hemi-veins and diastolic retinal artery of each eye in glaucoma patient volunteers and family members.
Blood pressure was measured with the sphygmomanometer cuff held at eye level. In pigs, the relationship between induced IOP and ODF was strong (minimum r > 0.98, p < 0.001). In humans, the pressure increment (blood pressure - baseline IOP) correlated highly with human arterial ODF (r = 0.83, n = 75, p < 0.001, mean slope 0.32). Mean coefficients of variation were 12.4% (n = 66) for veins and 5.6% (n = 39) for arteries in diastole; these results did not differ significantly with those from the Meditron but were significantly lower than results with the Sisler (20%, p = 0.0014).
Linearity between induced IOP and ODF is strong, suggesting that calibration of 0.32 mmHg/g for OcuDyn or using two point blood pressure measures allows for valid interpolation. The better optics of the Meditron and OcuDyn result in more repeatable end-point determination and outweigh benefits conferred by signal averaging or slit lamp mounting. We calculate calibration factors of 0.89 mmHg/arbitrary unit for Meditron and 0.82 mmHg/g for Sisler. These factors may be useful in the estimation of ocular vascular, orbital, and cerebrospinal fluid pressures.
眼动力测量研究可以提供有关青光眼、脑脊液压力和血管疾病的有用临床信息，但由于眼压（IOP）方面的力的可重复性和未知校准而受到影响。本研究的目的是使用三种不同类型的眼动力计计算校准因子并确定关键设计原则。
我们使用带有连续信号采集和平均功能的环力传感器内的大接触镜构建了一种名为 OcuDyn 的改良眼动力计。将 OcuDyn 和 Sisler 眼动力计应用于通过套管连接到液体储液器和压力传感器的分离猪眼，以测量在增加力应用时引起的IOP。使用这两种设备和 Meditron 眼动力计，我们测量了青光眼患者志愿者和家庭成员每只眼睛的半静脉和舒张视网膜动脉产生搏动所需的最小眼动力计力（ODF）。
用血压计袖带在眼睛水平测量血压。在猪中，引起的 IOP 与 ODF 之间的关系很强（最小 r > 0.98，p < 0.001）。在人类中，压力增量（血压 - 基础 IOP）与人类动脉 ODF 高度相关（r = 0.83，n = 75，p < 0.001，平均斜率 0.32）。静脉的平均变异系数为 12.4%（n = 66），动脉舒张期为 5.6%（n = 39）；这些结果与 Meditron 的结果没有显著差异，但明显低于 Sisler 的结果（p = 0.0014）。
IOP 和 ODF 之间的线性关系很强，这表明 0.32 mmHg/g 的校准或使用两点血压测量可以进行有效插值。Meditron 和 OcuDyn 的更好光学效果导致更可重复的终点确定，并且超过了信号平均或裂隙灯安装带来的好处。我们计算出 Meditron 的校准因子为 0.89 mmHg/任意单位，Sisler 的校准因子为 0.82 mmHg/g。这些因子可能有助于估计眼血管、眼眶和脑脊液压力。
