Clock-hour laminar displacement and age in primary open-angle glaucoma and normal tension glaucoma.

BACKGROUND: To find out the relationship between laminar displacement and age between patients with primary open-angle glaucoma and normal tension glaucoma.
DESIGN: Retrospective study conducted at a tertiary university hospital. PARTICIPANTS OR SAMPLES: Twenty-six eyes of 26 primary open-angle glaucoma patients and 52 eyes of 52 normal tension glaucoma patients.
METHODS: Patients were scanned with a Stratus optical coherence tomography apparatus to measure the retinal nerve fibre layer thickness and to visualize the cross-sectional laminar displacement of 12 clock-hour segments, 30 degrees each. Depth1 was defined as the longest distance between the retinal pigment epithelium and the anterior laminar cribrosa surface, which represents the amount of laminar displacement. MAIN OUTCOME MEASURE: Partial correlation coefficients adjusted by mean deviation and intraocular pressure between (i) retinal nerve fibre layer thickness and age, and (ii) Depth1 and age.
RESULTS: In the primary open-angle glaucoma group, strong negative correlations (approximately -0.343 ≈ -0.738) were found between Depth1 and age. Eight of 12 clock-hour segments' correlations were significant after Bonferroni correction (α = 0.0021; 24 comparisons). However, no significant correlations were found between Depth1 and age in the normal tension glaucoma group. When the correlation coefficients were compared between the two groups, eight clock-hour segments showed significant differences after Bonferroni correction.
CONCLUSIONS: The significantly different correlation between laminar displacement and age between primary open-angle glaucoma and normal tension glaucoma patients may suggest a different role of the lamina cribrosa to the disease.