Título

MEASUREMENT OF THE OPTIC NERVE HEAD DESCENDING FIBERS AT BRUCH’S MEMBRANE OPENING LEVEL WITH SD-OCT IN NORMAL AND GLAUCOMA EYES

Objetivo

This study aims to evaluate the mean descending fibers width at the Bruch’s membrane opening level (DF-BMO) and its association with structural and functional parameters in normal and glaucoma patients.

Método

Subjects with glaucoma presenting typical optic nerve head (ONH) findings, high intraocular pressure with or without visual field (VF) damage and normal controls were included. Patients underwent 24-2 perimetry and SD-OCT. A vertical B-scan of the ONH with the largest cup extension was obtained for the measurements. The mean width between the BMO and the innermost portion of the descending fibers at the inferior and superior portions of the cup constituted the DF-BMO (Figure 1). OCT measurements were analyzed and plotted using the average of the sectors from the ETDRS grid. Statistical analysis was performed using generalized estimating equations to allow for clustered observations. Age, gender, glaucoma and disc area were accounted in the model. The area under the receiver operating characteristics curve (AUROC) to discriminate between glaucoma and control was calculated.

Resultado

109 eyes (67 subjects) qualified for the study. The mean age was 66±12. The number of eyes was 95 in the glaucoma and 14 in the control group. The DF-BMO was 260±106µm and 476±125µm (P<0.001), respectively. DF-BMO was significantly associated with the VF parameters, circumpapillary RNFL (cRNFL) and the inner and outer circles of the ganglion cell/inner plexiform layer (GCIPL). The superior portion of the DF-BMO was associated with the superior cRNFL, as well as their inferior counterparts (Table). The AUROC was 0.896, P<0.001 (Figure 2). At the cutoff value of 365µm, the positive predictive value was 96.3%.

Conclusão

The DF-BMO was significantly associated with structural and functional glaucoma parameters, and differentiated well between normal and glaucoma patients. This parameter may constitute an additional OCT biomarker for the diagnosis and monitoring of glaucoma.