2M.D. Professor, Pamukkale University Faculty of Medicine, Department of Ophthalmology, Denizli/TURKEY Purpose: To evaluate retinal nerve fiber layer (RNFL) and optic nerve head characteristics of eyes with early visual field (VF) damage using spectral domain optical coherence tomography (SD-OCT) in primary open angle glaucoma (POAG).
Materials and Methods: Forty-five eyes with early glaucoma based on Hodapp-Parrish-Anderson classification (early glaucoma group) and 42 healthy eyes with normal SD-OCT and VF tests (control group) were retrospectively reviewed. The SD-OCT parameter values (average, superior, inferior, nasal and temporal RNFL thicknesses, RNFL symmetry, rim area, disc area, average cup/disc ratio [C/D], vertical C/D ratio and cup volume) were compared between the early glaucoma and control groups. Moreover, a receiver operating characteristic (ROC) analysis was performed and the area under the ROC curve (AUC) was calculated for the each OCT parameter to determine diagnostic cut points for early glaucoma.
Results: The average, superior, inferior, nasal and temporal RNFL thicknesses, RNFL symmetry and rim area values were decreased, and average C/D, vertical C/D and cup volume were increased in the early glaucoma group compared to those of the control group (P<0.05). Average, superior, and inferior RNFL thicknesses and rim area showed good diagnostic performance based on AUC values (AUCs>0.80). Values of 84, 110, 113 microns and 1.24 mm2 (respectively) were found as the cut points for early glaucomatous VF defect.
Conclusions: The SD-OCT parameters appear to be diminished in eyes with early glaucomatous VF damage. Moreover, cut points regarding average, superior, inferior RNFL thicknesses and rim area might assist in discriminating early glaucoma from normal in clinical practice.
Keywords : Cut point; early glaucoma; optical coherence tomography; receiver operating characteristic; visual field