Eye Department, Wellington Hospital, Capital and Coast District Health Board, Wellington, New Zealand.
Ophthalmology. 2012 Mar;119(3):443-9. doi: 10.1016/j.ophtha.2011.07.058. Epub 2011 Oct 27.
To evaluate the usefulness of the central corneal thickness (CCT)-based correction formulae for stratified CCT groups, with intraocular pressure (IOP) from the Pascal dynamic contour tonometer (PDCT) as the reference standard.
Retrospective case series.
Two hundred eighty-nine patients attending a specialist glaucoma practice and a mixture of normal subjects and subjects with confirmed glaucomatous optic neuropathy.
Intraocular pressure was measured using PDCT, Goldmann applanation tonometry (GAT), and the Ocular Response Analyzer (ORA; Reichert Corp, Buffalo, NY). The GAT readings were obtained before automated readings and were adjusted for CCT using 4 different correction formulae. Discrepancies between GAT and CCT-corrected GAT readings were evaluated after stratification into thin, intermediate, and thick CCT groups. The IOP measurements from GAT, the ORA, and CCT-adjusted IOP were compared against PDCT IOP measurements using Bland-Altman analysis.
Mean, 95% limits of agreement, and proportion of patients with IOP difference of 20% or more between PDCT IOP and each of GAT IOP, Goldmann-correlated IOP (IOPg), corneal-compensated IOP (IOPcc), and adjusted IOP using CCT-based correction formulae.
Average PDCT IOP values were higher than GAT, IOPg, IOPcc, and CCT-adjusted IOP. The GAT IOP readings demonstrated poor agreement with PDCT IOP (95% limits of agreement, ± 4.7 mmHg); however, IOPg, IOPcc, and adjustment of GAT IOP with CCT-based formulae resulted in even poorer agreement (range of 95% limits of agreement, ± 5.1 to 6.7 mmHg). If PDCT was used as the reference standard, there was a 26% to 39% risk of making an erroneous IOP adjustment of magnitude of 20% or more at all levels of CCT. This risk was greatest in the patients with thicker corneas (CCT, ≥568 μm).
Adjusting IOP using CCT-based formulae resulted in poorer agreement with PDCT IOP when compared with unadjusted G AT IOP. If PDCT is the closest measure we have to intracameral IOP, there is a risk of creating clinically significant error after adjustment of GAT IOP with CCT-based correction formulae, especially in thicker corneas. This study suggests that although CCT may be useful in population analyses, CCT-based correction formulae should not be applied to individuals.
评估基于中央角膜厚度（CCT）的校正公式在分层 CCT 组中的有用性，以帕斯卡动态轮廓眼压计（PDCT）的眼压（IOP）作为参考标准。
回顾性病例系列。
289 名就诊于专科青光眼诊所的患者，以及正常受试者和确诊青光眼视神经病变的受试者的混合群体。
使用 PDCT、Goldmann 压平眼压计（GAT）和 Ocular Response Analyzer（ORA；Reichert 公司，纽约州布法罗）测量眼压。在进行自动读数之前，获得 GAT 读数，并使用 4 种不同的校正公式根据 CCT 进行调整。将 GAT 读数分层为薄、中、厚 CCT 组后，评估 GAT 读数与 CCT 校正 GAT 读数之间的差异。使用 Bland-Altman 分析比较 GAT、ORA 和 CCT 校正眼压与 PDCT 眼压测量值。
平均、95%一致性界限和 PDCT 眼压与 GAT 眼压、Goldmann 相关眼压（IOPg）、角膜补偿眼压（IOPcc）和基于 CCT 的校正公式校正后的眼压之间差异为 20%或更多的患者比例。
平均 PDCT IOP 值高于 GAT、IOPg、IOPcc 和 CCT 校正的 IOP。GAT IOP 读数与 PDCT IOP 一致性较差（95%一致性界限，±4.7mmHg）；然而，IOPg、IOPcc 和 GAT IOP 的 CCT 校正公式的调整导致一致性更差（95%一致性界限范围，±5.1 至 6.7mmHg）。如果 PDCT 作为参考标准，在所有 CCT 水平，调整 GAT IOP 的 20%或更多的大小会导致 26%至 39%的错误 IOP 调整的风险。在角膜较厚的患者（CCT≥568μm）中，这种风险最大。
与未经校正的 GAT IOP 相比，使用基于 CCT 的公式调整 IOP 会导致与 PDCT IOP 的一致性更差。如果 PDCT 是我们最接近眼内压的测量值，那么在用基于 CCT 的校正公式调整 GAT IOP 后，可能会产生具有临床意义的错误，尤其是在角膜较厚的情况下。本研究表明，尽管 CCT 可能在人群分析中有用，但不应将基于 CCT 的校正公式应用于个体。
