Glaucoma diagnostic ability of the new circumpapillary retinal nerve fiber layer thickness analysis based on bruch’s membrane opening

PURPOSE. To compare the diagnostic ability of the new spectral-domain optical coherence tomography (SD-OCT) algorithm for measuring circumpapillary retinal nerve fiber layer (RNFL) thickness centered on Bruch’s membrane opening (BMO), with the conventional circumpapillary RNFL thickness measurement centered on the optic disc. METHODS. In 75 eyes with primary open-angle glaucoma (POAG) and 71 healthy control eyes, circumpapillary RNFL thickness was measured with SD-OCT, first by centering the scan circle on the optic disc (RNFL_Di), and then on the BMO (RNFL_BMO). Difference between the topographic profiles of RNFL_Di and RNFLBMO was compared and factors influencing any discrepancies between methods were investigated. Glaucoma diagnostic abilities of each method were assessed using the areas under receiver operating characteristic curve (AUCs). RESULTS. Axial length did not differ between POAG and healthy eyes. A longer axial length and larger width of externally oblique border tissue (BT) associated with tilted optic disc were thetwo major factors influencing discrepancies between RNFL_BMO and RNFL_Di (both P < 0.001). Compared with RNFL_BMO, RNFL_Di tended to result in a thinner nasal RNFL in eyes with externally oblique BT, while RNFL_BMO and RNFL_Di were comparable in eyes without externally oblique BT. The glaucoma diagnostic capabilities were generally comparable, but RNFL_BMO was superior to RNFL_Di in eyes having a larger width (>250 µm) of externally oblique BT (AUC ¼ 0.933 vs. 0.843, respectively, P ¼ 0.027). CONCLUSIONS. The new circumpapillary RNFL scanning algorithm centered on BMO may provide a more reliable RNFL profile in eyes with tilted optic discs, with a largely comparable glaucoma diagnostic ability to the conventional algorithm.