Laminar thickness measurement was more reliable than peripapillary retinal nerve fiber layer thickness measurement in diagnosing normal tension glaucoma, according to a study.
The study included 68 patients with primary open-angle glaucoma and 76 patients with normal-tension glaucoma. A control group comprised 65 healthy patients. The Spectralis optical coherence tomography system (Heidelberg Engineering) was used to image the peripapillary retinal nerve fiber layer (RNFL) and optic nerve head.
Investigators established a receiver operating characteristic (ROC) curve and calculated areas under the ROC curve (AUCs) to gauge the diagnostic ability of RNFL thickness and lamellar thickness measurements.
Mean laminar thickness was 215.41 µm in the glaucoma groups and 349.08 µm in the control group; the difference was statistically significant (P < .001).
Mean laminar thickness was 235.15 µm in the primary open-angle glaucoma group and 174.36 µm in the normal tension glaucoma group; the difference was statistically significant (P < .001). Average RNFL thickness, vertical cup-to-disc ratio and visual fields were similar in the glaucoma groups.
AUCs were 0.989 for mean laminar thickness and 0.947 for inferior RNFL thickness in the normal tension glaucoma group; the difference in diagnostic reliability for the two parameters was statistically significant (P = .047).