Relationship between disc margin to fovea distance and central visual field defect in normal tension glaucoma.

Abstract

BACKGROUND: To investigate the relationship between ocular geometric factors,

including temporal disc margin to fovea distance (DFD) measured by optic disc

stereophotography (ODP) and central visual field (VF) defect, in normal-tension

glaucoma (NTG) patients. METHODS: This retrospective, single-center,

cross-sectional study included 88 eyes of 88 NTG patients with mild VF defects

(MD > -6.0 dB). NTG patients were divided into two groups according to VF tests:

central VF-invading and central VF-sparing groups. Optic nerve head (ONH)

parameters including disc dimensions, peripapillary atrophy (PPA), and DFD were

obtained by ODP, and retinal nerve fiber layer (RNFL) thickness was measured by

Stratus optical coherence tomography (OCT). RESULTS: In the invading group, DFD

was shorter (3.642 +/- 0.401 mm) than in the sparing group (3.877 +/- 0.278 mm; p

= 0.002). The sparing group had more vertically oval ONH (p = 0.023) and wider

temporal PPA width (p = 0.031). The RNFL thickness in the invading group was

thinner in the temporal and inferior quadrants, but thicker in the superior

quadrant than that of the sparing group. In a multiple linear regression

analysis, DFD was the only geometric factor associated with degree of central VF

involvement (p = 0.002). DFD was positively correlated with temporal RNFL

thickness in the sparing group (r = 0.484, p < 0.001) but not in the invading

group (r = -0.080, p = 0.631). CONCLUSIONS: Eyes with a shorter DFD should be

monitored carefully because central VF involvement appears to be related to

shorter DFD in NTG patients with mild VF defects.