Instituto Mexicano de Oftalmología IAP, Querétaro City, Querétaro, México.
Fortis Memorial Hospital, New Delhi, India.
J Glaucoma. 2020 Sep;29(9):756-760. doi: 10.1097/IJG.0000000000001592.
PRéCIS:: Intraocular pressure (IOP) measurement differences with Goldmann applanation tonometry (GAT) and dynamic contour tonometry (DCT) are affected by atmospheric pressure inside a hyperbaric chamber.
To compare IOP measurements obtained with GAT and DCT in 22 normal individuals at different atmospheric pressures simulated in a hyperbaric chamber.
The IOP of both eyes of 22 healthy volunteers was measured using GAT and DCT at 4 different atmospheric pressure levels.Starting at 1 Queretaro atmospheric pressure (QATM), the IOP was measured with GAT and DCT. The atmospheric pressure was then increased to 1.1 QATM (equivalent to 1032 m above sea level), 1.2 QATM (equivalent to 315 m above sea level), and 1.25 QATM (equivalent to sea level), starting 5 minutes after reaching each level. The limits of agreement between various measurements with each tonometer were calculated using the Bland-Altman plots.
The first 4 subjects were used to measure feasibility, consistency, variability, and the time needed for IOP to return to baseline after each atmospheric pressure increase.For the entire 44 eyes, the mean GAT IOP at 1 QATM was 12.23 mm Hg (range, 8 to 20 mm Hg; SD, 2.84) and mean DCT was 16.36 (range, 12.1 to 25.3; SD, 2.84), with a mean 4.14 mm Hg difference (range, -0.1 to 7.5 mm Hg; SD, 1.62; P<0.001).Using the second measurements of the first 4 subjects and those after 5 minutes of adaptation for the rest of the group at 1.1 QATM, mean GAT IOP was 11.05±2.68 mm Hg and mean DCT IOP was 15.60±3.02 mm Hg, for a mean difference between instruments of 4.56±1.81 mm Hg (P<0.001).At 1.2 QATM, mean GAT IOP was 11.14±2.53 mm Hg and mean DCT IOP was 15.39±2.91 mm Hg. The difference between instruments was 4.25±2.12 mm Hg (P<0.001).At 1.25 QATM, the mean GAT IOP was 12.39±3.11 mm Hg and mean DCT IOP was 14.91±2.73 mm Hg. The difference between instruments after 5 minutes of adaptation was 2.53±1.62 mm Hg (P<0.001).Generalized estimating equations for performing linear regression multivariable analysis using atmospheric pressure, expressed as altitude, and age as covariates, shows that the difference between GAT and DCT increases by 1 mm Hg per 673 m of increase of altitude above sea level. Age was not a significant predictor.
Acute changes in atmospheric pressure induce changes in IOP measurements for both GAT and DCT and in different directions. Despite the limitation of sample size, it may be postulated that the difference of IOP measurements between the 2 tonometers increases with lower atmospheric pressures.
目的：比较在高压舱内模拟不同大气压力下，Goldmann 压平眼压计（GAT）和动态轮廓眼压计（DCT）测量的眼压（IOP）。
方法：对 22 名健康志愿者的双眼分别使用 GAT 和 DCT 在 4 个不同的大气压力水平下进行 IOP 测量。从 1 个墨西哥城大气压（QATM）开始，使用 GAT 和 DCT 测量 IOP。达到每个水平后 5 分钟，将大气压力增加到 1.1QATM（相当于海拔 1032 米）、1.2QATM（相当于海拔 315 米）和 1.25QATM（相当于海平面）。使用 Bland-Altman 图计算两种眼压计之间各种测量值的一致性。
结果：前 4 位受试者用于测量可行性、一致性、变异性以及每次大气压力升高后眼压恢复到基线所需的时间。对于所有 44 只眼睛，1QATM 时 GAT 的平均 IOP 为 12.23mmHg（范围为 8 至 20mmHg；SD，2.84mmHg），DCT 平均为 16.36mmHg（范围为 12.1 至 25.3mmHg；SD，2.84mmHg），平均差异为 4.14mmHg（范围为-0.1 至 7.5mmHg；SD，1.62mmHg；P<0.001）。使用前 4 位受试者的第 2 次测量值和其余受试者在 1.1QATM 适应 5 分钟后的测量值，GAT 的平均 IOP 为 11.05±2.68mmHg，DCT 的平均 IOP 为 15.60±3.02mmHg，两种仪器的平均差异为 4.56±1.81mmHg（P<0.001）。在 1.2QATM 时，GAT 的平均 IOP 为 11.14±2.53mmHg，DCT 的平均 IOP 为 15.39±2.91mmHg。仪器之间的差异为 4.25±2.12mmHg（P<0.001）。在 1.25QATM 时，GAT 的平均 IOP 为 12.39±3.11mmHg，DCT 的平均 IOP 为 14.91±2.73mmHg。适应 5 分钟后仪器之间的差异为 2.53±1.62mmHg（P<0.001）。使用大气压力（以海拔高度表示）和年龄作为协变量进行多元线性回归的广义估计方程表明，GAT 和 DCT 的IOP 测量值随海拔高度每升高 1mmHg 而增加 1mmHg。年龄不是一个显著的预测因素。
结论：大气压力的急性变化会导致 GAT 和 DCT 的 IOP 测量值发生变化，且变化方向不同。尽管样本量有限，但可以假设两种眼压计之间的 IOP 测量值差异会随着大气压力的降低而增加。
