Objective: To investigate the clinical differences between the two groups depending on the peak intraocular pressure(IOP) in patients with normal-tension glaucoma(NTG).

Methods: We studied 96 eyes of 48 NTG patients who were hospitalized for diurnal IOP measurement. Then we selected the eye whose peak IOP was higher than the other, or the right eye if the peak IOP of both eyes was equal. We divided these eyes into a "high-teen" group (peak IOP > or = 16 mmHg) and a "low-teen" group(peak IOP < or = 15 mmHg). We compared these two groups by age, gender, refraction, IOP, visual field defect, optic disc appearance, and tomograph. We used a Humphrey C 30-2 program to estimate the visual field defect and classified the optic disc into four types according to Nicolela's criteria. 22 eyes were imaged with Heidelberg Retina Tomograph (HRT) to obtain topographic parameters of the optic disc.

Results: There were no significant differences in age, gender, refraction, optic disc appearance, or tomograph between two groups. The trough and variation range of diurnal IOP were significantly larger in the high-teen group(p < 0.01). The value of mean deviation(MD) given by STATPAC was statistically lower in the high-teen group(p < 0.01).

Conclusions: In patients with NTG, the visual field damage tended to be greater in the high-teen group than in the low-teen group. We surmise that the IOP might influence the progression of visual field defect in NTG.