Abstract
Purpose :
Background
Strain at the lamina cribrosa of optic nerve is one of pathophysiology of glaucomatous damage. Measuring lamina cribrosa depth (LC-depth) is challenging. Previous published reference plane was the Bruch’s membrane opening(BMO) which was confounded by several factors for example, aged related choroid thickness differing and posterior migration of itself.
Objective
To determine the difference of lamina cribrosa depth (LC-depth) of optic disc imaging by optical coherence tomography (OCT) by different reference planes.
Methods :
This was an age-matched cross sectional study comparing LC-depth imaging of optic disc image which were taken by enhanced depth imaging (EDI) technique of OCT radial scan. LC-depth was the perpendicular vertical line between the reference plane to anterior lamina cribrosa. We measured LC-depth from 2 references; the first was the peri-papillary Bruch’s membrane (BM) layer at 3600 µm diameter of ETDRS grid-circle whereas, the second was the peri-papillary anterior scleral (AS) layer. (Figure1) The mean LC-depth from BM’s layer and AS’s layer between groups were compared. Descriptive statistics and generalized estimating equations were applied to compare demographic data and ocular parameters between groups.
Results :
We included 51 eyes from each groups. Confounding factors were controlled by matching the age between groups. Almost all demographic data were equivalent. Ocular parameters such as intraocular pressure(IOP), spherical equivalent, axial length, disc area and choroid thickness were similar. Mean LC-depth of glaucoma suspected and glaucomatous groups from both references were deeper than normal group significantly; LC-Depth(BM’s layer): 590.5 ± 108.4, 620.2 ± 166.3 vs. 512.1 ± 120.6, p = 0.003, LC-depth(AS’s layer): 425.5 ± 101.4, 481.4 ± 147.2 vs. 381.0 ± 117.0, p=0.007. (Table 1)
Conclusions :
The lamina cribrosa displaced more posterior in both glaucoma suspected and glaucoma comparing with normal. Both peri-papillary references could be visualised and measured the depth of LC correctly.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.