To assess the distinction ability for differentiating glaucoma patients based on optic disc, retinal nerve fiber layer (RNFL) and ganglion cell-inner plexiform layer (GCIPL) measured using spectral domain optical coherence tomography (SD-OCT). Additionally, the diagnostic ability of these parameters was evaluated by comparing preperimetic glaucoma patients who frequently visited the clinic and normal patients with and without a large physiologic cup/disc (C/D) ratio.

Using SD-OCT, the optic disc, RNFL and GCIPL of preperimetic glaucoma patients were compared with normal people with and without a large C/D ratio from March, 2011 to December, 2014 at Department of Ophthalmology, Inha University Hospital. Preperimetic glaucoma was defined using the normal standard automated perimetry for glaucomatous optic nerve changes such as asymmetry of vertical C/D ratio, rim thinning, notching, excavation and RNFL defect.

When comparing preperimetic glaucoma patients to normal people without large disc cupping, the most reliable parameter for optic disc parameters, vertical C/D ratio (0.89), showed more reliable diagnostic ability than the most reliable parameter for retinal nerve fiber, inferior RNFL thickness (0.79) and superonasal and inferonasal GCIPL thickness were the most reliable GCIPL parameters (p = 0.005 and 0.002, respectively). When comparing preperimetic glaucoma patients to normal people having a large physiologic disc cupping, average C/D ratio among optic nerve parameters, inferior RNFL thickness among RNFL thickness parameters and inferior GCIPL thickness among GCIPL parameters showed highly reliable diagnostic abilities. These 3 parameters were not statistically different (all p > 0.05) and had lower distinction ability than reported in previous studies.

Diagnostic abilities of SD-OCT for distinguishing preperimetric glaucoma from normal people having large physiologic disc cupping were similar for optic disc, RNFL and GCIPL and showed low diagnostic ability than compared to normal people without large disc cupping.