Anterior Laminar Cribrosa Surface Depth as a Diagnostic Parameter for Glaucoma

Abstract

 

Purpose

 

To investigate the diagnostic capability of the anterior lamina cribrosa surface depth (ALCSD) for glaucoma.

 

Methods

 

Normal subjects and glaucoma patients at various disease stages were recruited. Each participant had a complete ophthalmologic examination including standard automated perimetry (SAP) and circumpapillary retinal nerve fiber layer (RNFL) imaging using spectral-domain optical coherence tomography (OCT). Serial horizontal enhanced depth imaging (EDI) OCT B-scans of the optic nerve head were obtained from each participant (interval between scans, ~30 μm). After delineating the anterior lamina cribrosa surface, ALCSD (reference plane, Bruch’s membrane edges) under the Bruch’s membrane opening (Fig 1A) was measured in 11 equally spaced horizontal B-scans and averaged to generate mean ALCSD for one eye of each participant. Receiver operating characteristic (ROC) curves were obtained for mean ALCSD and average RNFL thickness (RNFLT). Areas under the ROC curve (AUCs) and sensitivities at a fixed specificity (90%) were compared between mean ALCSD and average RNFLT.

 

Results

 

86 normal eyes (mean age, 56±14 years) and 162 glaucoma eyes (47 with pre-perimetric glaucoma, 55 with SAP mean deviation [MD] ≥-12 dB and 60 with SAP MD <-12 dB; mean age = 60±16, 59±16 and 59±17 years, respectively) were included. ALCSD showed a Gaussian distribution in normal eyes (p=0.08) and a skewed distribution in glaucoma eyes (p<0.001) (Fig 1B and 1C). Mean ALCSD was significantly greater in glaucoma than in normal eyes (429±98 µm vs. 355±66 µm, p<0.001). The AUC of ALCSD was 0.729 for all glaucoma eyes, 0.672 for pre-perimetric eyes, 0.792 for glaucoma eyes with MD ≥-12 dB, and 0.717 for eyes with MD <-12 dB (all p<0.001; Fig 2). For pre-perimetric glaucoma eyes, the AUC of ALCSD was comparable to that of RNFLT (p=0.17, Fig 2B); the sensitivities of ALCSD and RNFLT at a specificity of 90% were 34.0% and 38.3%, respectively. However, the AUC of ALCSD was significantly smaller than that of RNFLT for glaucoma eyes with SAP MD either ≥ or <-12 dB (both p<0.001, Fig 2C and 2D); the sensitivities of ALCSD and RNFLT at a specificity of 90% were 50.9% and 84.8% for eyes with MD ≥-12 dB and 46.7% and 100% for eyes with MD <-12 dB, respectively.

 

Conclusions

 

Diagnostic capability of ALCSD was comparable to that of RNFLT in pre-perimetric glaucoma. In glaucoma eyes with SAP visual field loss, RNFLT had better diagnostic value than ALCSD.

 

 

 

Keywords: 577 lamina cribrosa • 495 depth • 550 imaging/image analysis: clinical