Relationship between Progressive Changes in Lamina Cribrosa Depth and Deterioration of Visual Field Loss in Glaucomatous Eyes

Abstract

Purpose: To investigate the relationship between the progression of visual field (VF) loss and changes in lamina cribrosa depth (LCD) as determined by spectral-domain optical coherence tomography (SD-OCT) enhanced depth imaging in patients with primary open angle glaucoma (POAG).

Methods: Data from 60 POAG patients (mean follow-up, 3.5 ± 0.7 years) were included in this retrospective study. The LCD was measured in the optic disc image using SD-OCT enhanced depth imaging scanning at each visit. Change in the LCD was considered to either 'increase' or 'decrease' when the differences between baseline and the latest two consecutive follow-up visits were greater than the corresponding reproducibility coefficient value (23.08 μm, as determined in a preliminary reproducibility study). All participants were divided into three groups: increased LCD (ILCD), decreased LCD (DLCD), and no LCD change (NLCD). The Early Manifest Glaucoma Trial criteria were used to define VF deterioration. Kaplan-Meier survival analysis and Cox's proportional hazard models were performed to explore the relationship between VF progression and LCD change.

Results: Of the 60 eyes examined, 35.0% (21 eyes), 28.3% (17 eyes), and 36.7% (22 eyes) were classified as the ILCD, DLCD, and NLCD groups, respectively. Kaplan-Meier survival analysis showed a greater cumulative probability of VF progression in the ILCD group than in the NLCD (p < 0.001) or DLCD groups (p = 0.018). Increased LCD was identified as the only risk factor for VF progression in the Cox proportional hazard models (hazard ratio, 1.008; 95% confidence interval, 1.000 to 1.015; p = 0.047).

Conclusions: Increased LCD was associated with a greater possibility of VF progression. The quantitative measurement of LCD changes, determined by SD-OCT, is a potential biomarker for the prediction of VF deterioration in patients with POAG.

Keywords: Glaucoma; Lamina cribrosa; Optic disk; Optical coherence tomography; Visual fields.

Fig. 1. Measurement of lamina cribrosa depth (LCD) by spectral-domain optical coherence tomography. (A) En-face images of the optic nerve head were obtained from spectral-domain optical coherence tomography enhanced depth imaging scanning. Among several B-scans from optic disc scanning, a horizontal section image passing through major vessel trunks was selected to measure the LCD. This image-selecting procedure was repeated in the same eye at each follow up visit. (B) A line connecting the Bruch's membrane opening (red dots) on each side was regarded as the Bruch's membrane opening plane. The anterior surface of the lamina cribrosa was set as the horizontal margin, where the highly reflective region beneath the optic disc cup started. The distance of the three perpendicular lines (composed of the maximally depressed point, yellow arrow) from the reference line, and 100 and 200 µm apart from the maximally depressed point to temporal direction, were measured. A manual caliper tool and regions of interest manager of ImageJ software was used for each measurement and the LCD was determined by the average value measured from the three points.

Fig. 2. Subgroup analysis of lamina cribrosa displacement. The method of measuring lamina cribrosa depth (LCD) described in Fig. 1 was repeated at each follow-up visit. The values were determined at each follow-up visit and the difference from the first to the last measurement was considered LCD change. A significant LCD change was defined as a value greater, within and less than the reproducibility coefficient (23.08 µm). (A) Posteriorly displaced lamina cribrosa (LC), (B) no significant LC displacement, and (C) anteriorly displaced LC.

Fig. 3. Kaplan-Meier estimates of visual field progression during the follow up period. X-axis, follow-up period (year); Y-axis, cumulative probability of the visual field progression. ^*p< 0.05 considered as statistically significant. LCD = lamina cribrosa depth; ILCD = increased LCD; NLCD = no LCD change; DLCD = decreased LCD.