Abstract
Purpose :
To assess optic nerve head (ONH) pre-laminar neural tissue thickness (PLNTt) as a structural parameter in glaucoma, and to correlate it with conventional parameters in glaucomatous patients and healthy eyes.
Methods :
We conducted an observational case-control study, in which glaucomatous patients with a wide range of disease stage and healthy individuals were prospectively enrolled. A complete ophthalmological examination was performed and patients with significant media opacity or any ocular disease (besides glaucoma) were excluded. Serial vertical enhanced depth imaging spectral-domain optical coherence tomography (EDI-OCT) B-scans were used to determine PLNTt values for each patient (examiner masked to patients clinical data). Only good quality images were considered, and whenever both eyes were eligible, one was randomly selected. Average PLNTt values were compared between glaucomatous patients and controls. In addition, we investigated its discrimination ability and correlations with conventional peripapillary retinal nerve fiber layer (pRNFL) thickness and with disease stage (based on visual field index [VFI]).
Results :
A total 58 eyes of 58 patients were included (29 glaucomatous eyes and 29 controls). Mean VFI of glaucomatous eyes was 73±23.8%. Glaucomatous eyes had a significant thinner PLNTt compared to controls (96±44µm vs 277±212µm; p<0.01). There was a significant correlation between PLNTt and pRNFL thickness values (r=0.49; p<0.01). Although not statistically significant, there was a trend for a positive non-linear correlation between PLNTt and VFI (p=0.09). Comparison of areas under the receiver operating characteristic curves (AUCs) between the two structural parameters revealed a significant larger AUC for pRNFL (0.98) compared to PLNTt (0.77; p<0.01).
Conclusions :
Although in vivo assessment of ONH PLNTt revealed significant differences between glaucomatous and healthy eyes, its diagnostic performance was worse when compared to conventional pRNFL analysis. We believe that some limitations of this current method of PLNTt measurement (such as manual measurement, influence of disc size and image resolution) should be overcome in order to improve its usefulness as a potential parameter in glaucoma.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.