Abstract
Purpose:
To investigate the relationship between the ocular geometric factors measured by optic disc stereophotographs (ODP) and central visual field (VF) defect in normal tension glaucoma (NTG) patients.
Methods:
This retrospective study included eighty-eight eyes of 88 NTG patients with mild VF defect (MD > -6.0dB). NTG patients were divided into two subgroups, according to VF tests: the central VF-invading and central VF-sparing groups. Optic nerve head (ONH) parameters including disc dimensions, peripapillary atrophy (PPA) and distance between fovea and disc margin (DFD) were obtained by ODP and retinal nerve fiber layer thickness (RNFLT) was measured by Stratus optical coherence tomography (OCT).
Results:
Intraocular pressure was not different between groups but ocular pulse amplitude was higher in invading group (2.91 vs 2.43 mmHg, p=0.017) DFD of invading group (3.642 ± 0.401 mm) was shorter than 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 RNFLT of invading group was thinner in temporal and inferior quadrants, but thicker in superior quadrant than that of 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 RNFLT in sparing group (r=0.484, p<0.001) but not in invading group (r=-0.080, p=0.631).
Conclusions:
The central VF defect appears to be related with shorter DFD in the patients with mild NTG. It may suggest that the eyes with shorter DFD tends to manifest earlier central VF defect because they may have less structural reservoir resisting glaucomatous damage related to parafoveal involvement.
Keywords: 758 visual fields •
627 optic disc •
550 imaging/image analysis: clinical