Primary Angle-Closure Glaucoma With Normal Intraocular Pressure at the First Visit: Its Prevalence and Ocular Characteristics

Purpose: To investigate the prevalence of normal intraocular pressure (IOP) at first visit among patients with primary angle-closure glaucoma (PACG) and their ocular characteristics. Patients and Methods: We retrospectively reviewed patients with PACG in a referral center. According to untreated IOP, we divided PACG eyes into 2 groups: those with normal IOP and those with high IOP (>21 mm Hg) at the first visit. Results: One hundred sixty eyes of 160 Korean PACG patients were included. Sixty percent (97/160) of the patients had normal IOP at their first visit. The PACG patients with initially normal IOP had significantly longer axial length (mean +/- SD, 22.99 +/- 0.76 vs. 22.74 +/- 0.61) and deeper "true" anterior chamber depth (ACD) (2.09 +/- 0.27 vs. 1.82 +/- 0.33) than those with initially high IOP (both P<0.05). Multiple logistic regression revealed that deeper "true" ACD (per 0.1 mm; odds ratio, 1.38) and more hyperopic refractive errors (odds ratio, 1.48) were independent predictors of initially normal IOP in PACG eyes (P<0.05). The prevalence of disc hemorrhage was higher in PACG patients with initially normal IOP than in those with initially high IOP (29.9% vs. 14.3%, P=0.029). Conclusions: Sixty percent of patients with PACG had normal IOP at their first visit. This suggests that without gonioscopy clinicians may misdiagnose PACG as normal tension glaucoma. ACD measurement can aid the diagnosis of PACG because even PACG eyes with initially normal IOP have shallow ACD.