Comparison of the clinical characteristics of normal tension glaucoma patients with pretreatment intraocular pressures in the high-teens and low-teens

Anecdotal evidence suggests that normal-tension glaucoma (NTG) patients with mean intraocular pressures (IOP) in high-teens may differ from those in low-teens, in mechanisms of visual-field damage1 and retinal nerve fibre layer (RNFL) defects.2 This study aims to determine the potential differences in risk factors and rates of progression in these two groups. The methodology of this prospective cohort study, in particular, risk factors detection and definitions of field progression, were as per our previous publications,3 4 using serial applanation tonometry and automated visual field assessment. Presence of systemic diseases was captured from a computerised database in Hong Kong. Low-teens normal-tension glaucoma (LNTG) was defined as the maximum untreated office IOP ≤15 mm Hg in all serial visits. Those with untreated office IOP measurement >15 mm Hg in any visit were defined as high-teens normal-tension glaucoma (HNTG). All patients were followed up for 36 months and …