Comparison of optic nerve head topography and visual field in eyes with open-angle and angle-closure glaucoma

Abstract

Objective: To compare the optic disc and visual field (VF) alterations in primary open-angle glaucoma (POAG) and primary angle-closure glaucoma (PACG).

Design: Observational case series.

Participants: A total of 146 persons (217 eyes), 110 with POAG and 36 with PACG, recruited from a university glaucoma service.

Methods: Each subject underwent visual acuity measurement, applanation tonometry, gonioscopy, slit-lamp examination, dilated optic disc and retinal examination, axial eye length measurement, central corneal pachymetry, automated perimetry, optical coherence tomography (OCT) nerve fiber layer (NFL) examination, and Heidelberg Retina Tomograph (HRT) optic disc evaluation. Parameters of interest were studied by multivariate regression models.

Main outcome measures: Heidelberg Retina Tomograph parameters compared between POAG and PACG.

Results: Primary open-angle glaucoma and PACG groups were similar in age, ethnic background, and treated intraocular pressure, but the PACG group had significantly more women, shorter eye length, more hyperopia, and a larger disc area (all Ps < 0.001). The VF average mean deviation (MD) did not significantly differ between POAG and PACG, but the PACG group had lower pattern standard deviation (PSD) for a given MD (P = 0.001). Although 3 HRT parameters differed somewhat between POAG and PACG (cup area, rim area, and cup-to-disc area ratio), they did not significantly differ after correction for multiple comparisons. Mean deviation and disc area were much more significant predictors of the HRT measures than was diagnosis. Similar results were obtained when using OCT NFL thickness as a structural measure of damage as opposed to MD as a functional measure. When controlling for MD, current IOP was not significantly associated with disc parameters in POAG.

Conclusions: When the amount of optic nerve damage is taken into account by adjusting for VF MD or OCT NFL thickness, those with POAG and PACG have no significant differences in optic disc topography. Visual field damage in PACG was more diffuse than that in POAG, as measured by a lower PSD for a given level of MD. There was no corresponding difference in the uniformity of structural damage as measured by OCT NFL thickness.