Central corneal thickness of normal-tension glaucoma and non-glaucoma populations in ethnic Chinese

The variations in central corneal thickness can influence intraocular pressure measurement. The aim of our study was to determine whether there is a difference in the central corneal thickness between normal-tension glaucoma (NTG) and non-glaucoma populations.

This prospective study included 33 consecutive patients with NTG and 33 age- and gender-matched healthy subjects as control subjects. The NTG patients were grouped according to the refractive error into group 1 (spherical equivalent +2.5 D approximately -6.0 D) and group 2 (spherical equivalent more than -6.0 D). Central corneal thickness was measured using a ultrasonic pachymeter. The mean central corneal thickness of the NTG and healthy subjects were compared using the student t-test and Nilcoxon Rank Sum test.

The mean (+/- SD) central corneal thickness in the healthy subjects and NTG patients was 554.1 (+/- 36.3) and 547.2 (+/- 31.4) microns, respectively. There were no statistical significant differences between these two groups (p=0.411). The median central corneal thickness in the NTG group 1 and group 2 eyes was 545, and 547.5 microns, respectively. The difference was not statistically significant, either (p=0.799). Ten patients (30%) of NTG had high myopia (group 2), and their median age was 38.5 years old, which was significantly younger than that of the group 1 patients (50 years old, p = 0.0003).

This study indicated that there were no significant differences of central corneal thickness between NTG patients and healthy subjects in our clinic.