Differences in Factors Associated With Glaucoma Progression With Lower Normal Intraocular Pressure in Superior and Inferior Halves of the Optic Nerve Head.

Abstract

The purpose of this study was to investigate risk factors for progression in the superior and inferior hemi-visual fields (hemi-VFs) and the corresponding hemi-disc/retinas in eyes with normal tension glaucoma (NTG). A 5-year prospective follow-up of 90 patients with NTG with untreated intraocular pressure (IOP) consistently ≤ 15 mm Hg was conducted. The IOP and Humphrey Perimeter measurements and disc/retina stereo-photographs were taken every 3 and 6 months, respectively. Risk factors for progression in the superior and inferior hemi-VFs and in the superior and inferior hemi-disc/retinas were investigated. The mean total deviation values decreased at -0.50 ± 0.76 and -0.13 ± 0.34 dB/year in the superior and inferior hemi-VFs, respectively (P < 0.001). In the superior hemi-VF, the risk factor for faster progression was greater long-term IOP fluctuation (P = 0.022). In the inferior hemi-VF, the risk factors were disc hemorrhage (DH), greater myopic refraction, body mass index (BMI), and vertical cup-to-disc ratio (v-C/D; P < 0.05). The progression probability was 47.7 ± 6.0 and 17.7 ± 4.7% at 5 years in the superior and inferior hemi-disc/retinas respectively (P < 0.001), and DH was a risk factor for progression in both (P = 0.001). In NTG eyes, greater BMI, myopia, and v-C/D are characteristic risk factors for faster progression in the superior half of the optic nerve head (ONH), whereas long-term IOP fluctuation is the significant risk factor in the inferior half of the ONH, whereas DH is a risk factor in both. Different risk factors were identified in superior and inferior hemifields in NTG eyes.