Postural Response of Intraocular Pressure and Visual Field Damage in Patients With Untreated Normal-tension Glaucoma

PURPOSE: To evaluate whether postural changes of intraocular pressure (IOP) are associated with visual field damage by comparing both eyes of patients with previously untreated normal-tension glaucoma (NTG). PATIENTS AND METHODS: Forty eyes of 20 patients newly diagnosed as bilateral NTG were studied. IOP was measured in both sitting and supine positions, and the magnitude of IOP elevation with postural change (ΔIOP) was calculated. Visual field was examined using Humphrey Field Analyzer, and the mean deviation (MD) value was obtained. By comparing ΔIOP between the 2 eyes of a patient, eyes were classified into either small or large ΔIOP group. The MD was compared between these 2 groups. RESULTS: The ΔIOP was 3.2 ± 1.9 mm Hg [mean ± standard deviation (SD)] and 4.5 ± 2.3 mm Hg in the small and large ΔIOP eyes, respectively. The MD in the large ΔIOP eyes [-8.9 ± 6.2 dB (mean ± SD)] was significantly worse than that in the small ΔIOP eyes (-5.9 ± 4.7 dB) (P<0.001). CONCLUSIONS: More advanced visual field damage was observed in eyes with greater magnitude of IOP elevation with postural changes. IOP measurement in the supine position at the time of first diagnosis of NTG may facilitate the planning of treatment strategy.