Posterior Lamina Cribrosa Displacement at Different Stages of Glaucoma

Abstract

 

Purpose

 

To compare in vivo lamina cribrosa (LC) position between normal subjects and patients with glaucoma at different stages.

 

Methods

 

Normal subjects and glaucoma patients at various disease stages were recruited. All participants had a complete ophthalmologic examination including standard automated perimetry (SAP; 24-2 SITA-standard, Humphrey Field Analyzer). Serial horizontal enhanced depth imaging optical coherence tomography (EDI OCT) B-scans of the optic nerve head were obtained from each participant (interval between scans, ~30 μm). After delineating the anterior LC surface, mean LC depth (reference plane, Bruch’s membrane edges) was measured in 11 equally spaced horizontal B-scans for one eye of each participant, excluding the LC insertion area under Bruch’s membrane and the scleral rim (Fig A and B). Mean LC depth was compared among 1) normal eyes, 2) glaucomatous eyes with no visual field defects (VFD) (pre-perimetric glaucoma), and 3) glaucomatous eyes with VFD. Age, intraocular pressure (IOP) and angle of lateral LC displacement (Fig C) were recorded.

 

Results

 

62 normal eyes (mean age, 55±17 years), 43 pre-perimetric glaucoma eyes (mean age, 61±17 years), 104 glaucomatous eyes with VFD (mean age, 59±17 years; mean VF mean deviation [MD], -12.9±8.2 dB) were included. Mean LC depth was significantly different among the glaucoma with VFD, pre-perimetric glaucoma, and normal groups (434±102, 395±74, and 351±70 µm, respectively), before and after controlling for age, IOP and angle of lateral LC displacement (all p<0.03). Mean LC depth was significantly greater in the same order in all 11 scans after controlling for age, IOP and angle of lateral LC displacement (all p<0.04; Fig D). Among glaucomatous eyes with VFD, mean LC depth had no significant correlation with VF MD (p=0.14; Fig E).

 

Conclusions

 

In human glaucoma, posterior displacement of the central and mid-peripheral LC occurs mostly at earlier stages of glaucoma before the development of VFD detectable in SAP.

 

 

(A) White dots = Bruch’s membrane edges; black dots = anterior LC insertion points; mean LC depth = (area S/length D). (B) The circle indicates the LC. (C) Angle of lateral LC displacement (θ) was measured in the horizontal midline scan of the LC. Blue dot = midpoint between the 2 Bruch’s membrane edges. Red dot = midpoint between the 2 anterior LC insertion points. (D) Mean LC depth profiles. (E) Scatterplot of mean LC depth vs. VF MD.

 

Keywords: 577 lamina cribrosa • 552 imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • 550 imaging/image analysis: clinical