Focal Lamina Cribrosa Defects and Glaucomatous Visual Field Progression

Abstract

Purpose: : To compare glaucomatous visual field (VF) progression between eyes with and without focal lamina cribrosa (LC) defects.

Methods: : Serial horizontal and vertical enhanced depth imaging optical coherence tomography (EDI OCT) B-scans of the optic nerve head (interval between scans: approximately 30 µm) were obtained prospectively from glaucoma patients with 5 or more prior 24-2 VF tests. EDI OCT scans were reviewed for the presence of focal LC defects (focal LC disinsertion or full-thickness LC defect) that violated the smooth curvilinear contour of the normal anterior laminar surface. The maximum width of each focal LC defect was required to be ≥100 µm. Progression rates were calculated using pointwise linear regression (PLR) analysis and averaged to generate the global progression rate (dB/yr) for each eye. VF progression was defined as having ≥1 significantly progressing point(s) (slope <-1.0 dB /yr at P<0.01). The rates at these points were averaged to generate the localized progression rate (dB/yr) for each eye. Age, intraocular pressure [IOP], baseline visual field [VF] mean deviation [MD], a detected disc hemorrhage, and central corneal thickness [CCT] were recorded.

Results: : A total of 104 eyes were included (104 patients; mean age, 66±13 yr; mean baseline VF MD, -10.2±7.6 dB): 45 eyes had focal LC defects and 59 did not (control group). The mean number of VF tests (9.2 vs. 8.8) and follow-up period (6.7 vs. 7.1 yrs) were similar between the two groups (all P>0.2). Significantly more eyes had progressed in the LC defect group than in the control group (27 eyes [61%] vs. 16 eyes [27%]; P<0.001). Mean global (-0.61 vs. -0.22 dB/yr) and localized progression rates (-3.51 vs. -1.96 dB/yr) were significantly greater in eyes with focal LC defects than in those without (P=0.015 and 0.010, respectively), whereas the mean number of progressing points were similar between the two groups (5.4 vs. 5.1; P=0.5). After adjusting for age, mean follow-up IOP, baseline VF MD, disc hemorrhage detection, and CCT, however, there was a borderline, but non-significant difference between groups regarding global (P=0.08) and localized (P=0.16) progression rates. Among the evaluated parameters, the presence of focal LC defect and number of VF tests were significantly associated with VF progression in both univariate (OR, 4.27; P<0.001 and OR, 1.19; P=0.0027, respectively) and multivariate (OR, 4.87; P<0.001 and OR, 1.20; P=0.002, respectively) logistic regression analyses.

Conclusions: : Focal LC defect is highly associated with glaucomatous VF progression.

Keywords: lamina cribrosa • imaging/image analysis: clinical • visual fields