Emara B Y, Tingey D P, Probst L E, Motolko M A
Department of Ophthalmology, University of Western Ontario, London.
Can J Ophthalmol. 1999 Oct;34(6):319-24.
It is possible that the intraocular pressure (IOP) is underestimated in eyes whose central cornea is thinner than normal. The objective of this study was to determine and establish the significance of central corneal thickness in patients with low-tension (normal-tension) glaucoma compared with those with chronic open-angle glaucoma (COAG) or ocular hypertension and healthy eyes.
The study was carried out from February 1998 to May 1999. Central corneal thickness was measured by ultrasonic pachymetry and IOP was measured by Goldmann applanation tonometry in 25 patients with low-tension glaucoma (untreated IOP less than 21 mm Hg with evidence of optic nerve head damage and corresponding visual field loss on automated perimetry), 80 patients with COAG (untreated IOP 21 mm Hg or greater with evidence of optic nerve head damage and corresponding visual field loss on automated perimetry), 16 patients with ocular hypertension (untreated IOP 21 mm Hg or greater, with normal optic nerve head and no history of glaucoma or elevated IOP, and normal visual field on automated perimetry) and 50 control subjects (untreated IOP less than 21 mm Hg with normal optic nerve head and no history of glaucoma or elevated IOP). Analysis with Pearson's product-moment correlation was performed to determine the correlation of IOP and central corneal thickness, and one-way analysis of variance was used to compare corneal thickness between groups.
The central cornea was significantly thinner in the low-tension glaucoma group (mean 513.2 mu [standard deviation (SD) 26.1 mu]) than in the COAG group (mean 548.2 mu [SD 35.0 mu]) and the control group (mean 556.7 mu [SD 35.9 mu]) (p < 0.001). No significant difference in corneal thickness was found between the COAG and control groups. The ocular hypertension group had significantly thicker corneas (mean 597.5 mu [SD 23.6 mu]) than the three other groups (p < 0.001).
Patients with low-tension glaucoma may have thinner corneas than patients with COAG and healthy subjects. This results in underestimation of their IOP. Corneal thickness should be taken into account when managing these patients to avoid undertreatment.
中央角膜比正常薄的眼睛，其眼压可能被低估。本研究的目的是确定并确立低眼压（正常眼压）青光眼患者与慢性开角型青光眼（COAG）患者、高眼压症患者及健康眼睛相比，中央角膜厚度的意义。
研究于1998年2月至1999年5月进行。采用超声测厚法测量中央角膜厚度，用Goldmann压平眼压计测量眼压，对象包括25例低眼压青光眼患者（未经治疗的眼压低于21 mmHg，有视神经乳头损害证据且自动视野计检查有相应视野缺损）、80例COAG患者（未经治疗的眼压21 mmHg或更高，有视神经乳头损害证据且自动视野计检查有相应视野缺损）、16例高眼压症患者（未经治疗的眼压21 mmHg或更高，视神经乳头正常，无青光眼或眼压升高病史，自动视野计检查视野正常）以及50例对照者（未经治疗的眼压低于21 mmHg，视神经乳头正常，无青光眼或眼压升高病史）。采用Pearson积差相关分析确定眼压与中央角膜厚度的相关性，用单因素方差分析比较各组间的角膜厚度。
低眼压青光眼组中央角膜显著薄于COAG组（平均513.2μm[标准差（SD）26.1μm]）和对照组（平均556.7μm[SD 35.9μm]）（p<0.001）。COAG组与对照组之间角膜厚度无显著差异。高眼压症组角膜显著厚于其他三组（平均597.5μm[SD 23.6μm]）（p<0.001）。
低眼压青光眼患者的角膜可能比COAG患者和健康受试者薄。这导致其眼压被低估。治疗这些患者时应考虑角膜厚度，以免治疗不足。
