SS-OCT Discriminates Glaucomatous From Non Glaucomatous Optic Neuropathy

Swept-source optical coherence tomography (SS-OCT) can discriminate glaucomatous optic neuropathy (GON) from non glaucomatous optic neuropathy (NGON), with vertical cup-to-disc ratio (CDR), cup volume, and superior ganglion cell layer (GCL) thickness showing the highest predictive value, according to research published in Journal Français d’Ophtalmologie.

Researchers enrolled 189 participants in the retrospective, cross-sectional study, including individuals with GON (n=133; mean age, 71.75 years; 77 men) and patients with NGON (n=56; mean age, 57.30 years; 27 men). Individuals with ischemic optic neuropathy, previous optic neuritis, and compressive, toxic-nutritional, and traumatic optic neuropathy comprised the NGON cohort. Study participants underwent SS-OCT and the research team obtained peripapillary retinal nerve fiber layer (pRNFL) thickness measurements, GCL thickness measurements, and optic nerve head parameters. The team performed bivariate and multivariable logistic regression analyses using these values and calculated area under the receiver operating characteristic curve (AUROC) to discriminate GON from NGON.

The overall and inferior quadrant pRNFL thicknesses were thinner among individuals with GON compared with study participants with NGON (P =.044, P <.01, respectively), the report shows. Patients with NGON, however, had thinner temporal quadrants (P =.044).

Significant differences between the GON and NGON groups were noted for most optic nerve head parameters obtained by SS-OCT. Patients with NGON had thinner superior GCL compared with those with NGON(P =.015), but no significant differences were noted between overall GCL and inferior thickness between the 2 cohorts. Vertical CDR, cup volume, and superior GCL thickness demonstrated independent predictive values for differentiating GON from NGON, which along with age and disc area achieved an AUROC of 0.944 (95% CI, 0.898-0.991).

“Although glaucoma is the main cause of optic disc cupping and is the most prevalent optic neuropathy, non-glaucomatous optic neuropathies can mimic glaucoma, especially when [intraocular pressure] is in the normal range,” the study authors explain. “Because of this, discriminating GON from NGON can be challenging in certain cases, even for experienced observers, and avoiding misdiagnosis is important since it may have serious implications, such as a late diagnosis of a brain tumor.”

Study limitations include possible confounding due to the exclusion of patients with NTG in the GON cohort, the inclusion of individuals with advanced stages of optic neuropathy in both groups, and a single center design.