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Purpose of review A process is ongoing to produce a definition of glaucomatous optic neuropathy (GON) using quantitative, objective data from structural and functional tests. At present, a common practice is to define GON by subjective features said to be 'characteristic' as judged by those experienced in glaucoma care. Recent findings An objective definition would standardize the comparison of clinical research results across studies, without precluding simultaneous use of idiosyncratic definitions in the same reports. To achieve this goal, expert opinion was solicited to reach optimal agreement on one or more consensus, GON definitions. An interactive period of online discussion by 176 international experts led to 110 responses in an online survey that narrowed possible definitional structures into testable criteria. Summary Two approaches to validation of one or more sets of criteria for definite and possible GON are ongoing. The general principles include definition for each eye individually, inclusion of a borderline category, no intraocular pressure criterion, and both structural and functional defects in appropriate physical locations. Each validation approach uses clinician diagnosis as a standard against which objective criteria are compared, with the initial approach using a three-level categorical scale, and the second approach using 0--100 scaling.

To determine interocular differences in Bruch's membrane opening minimum rim width (BMO-MRW) and retinal nerve fiber layer thickness (RNFLT) in healthy Brazilian individuals.Both eyes of 220 healthy individuals were included in this observational, cross-sectional study. All individuals had normal clinical examination and visual fields. Global and sectorial interocular BMO-MRW and RNFLT differences, acquired and regionalized relative to the fovea to BMO center (FoBMO) axis, were calculated. The effect of age, axial length, and BMO area asymmetry on the parameters' asymmetry was evaluated.The 95th limits for interocular BMO-MRW and RNFLT global differences were 49 and 9 μm, respectively. BMO-MRW asymmetry was negatively correlated (β=-33.87 μm/mm, R=0.06, P0.001), whereas RNFLT asymmetry was positively correlated (β= 6.13 μm/mm, R=0.09, P0.001) with BMO area asymmetry. Neither BMO-MRW nor RNFLT asymmetries were correlated with axial length asymmetry (β=-16.90 μm/mm, R=0.00, P=0.15; β=-1.18 μm/mm, R=0.00, P=0.52, respectively). Similarly, BMO-MRW and RNFLT asymmetries were not correlated with age (β=0.17 μm/y, R=0.01, P=0.22; β=0.0 μm/y, R=0.00, P=0.19, respectively).Our results suggest that global BMO-MRW and RNFLT interocular differences exceeding 49 and 9 μm, respectively, may indicate statistically abnormal asymmetry, which may suggest early structural damage. Asymmetry in BMO area should be accounted for when considering interocular asymmetry in BMO-MRW and RNFLT.

PURPOSE To compare the visibility of deep optic nerve head (ONH) structures and the visible area of the anterior surface of the lamina cribrosa (ASLC) with spectral-domain optical coherence tomography (SD-OCT) and swept-source OCT (SS-OCT). MATERIALS AND METHODS In total, 33 glaucoma patients were imaged with SD-OCT (Spectralis, 24 radial B-scans centered on the ONH) and SS-OCT (Atlantis, 12 radial and a horizontal and vertical raster scan pattern containing 5 lines each, centered on the ONH). One of the SS-OCT horizontal and vertical scans that was best matching with the horizontal and vertical scan lines with those of SD-OCT was selected. All B-scans were then exported and deidentified. An independent observer determined whether the posterior choroid, border tissue, anterior scleral canal opening, and LC insertion into the sclera were detectable in the matched scan lines. Bruch membrane opening (BMO) and ASLC were segmented manually in radial scans. The segmented points were combined into a single plane and a linear interpolation was used to define BMO and ASLC areas. RESULTS The posterior choroid, border tissue, and anterior scleral canal opening were detectable in most patients (94% to 100%, 88% to 100%, and 76% to 100%, respectively) and were not different between SD-OCT and SS-OCT. The LC insertion detection rate was nonstatistically higher for SS-OCT compared with SD-OCT (58% to 85% vs. 42% to 73%; P>0.10). The mean (SD) ASLC visible area (percentage of the respective BMO area) was 124 (30%) with SD-OCT and 135 (32%) with SS-OCT (P