Automated macular segmentation in compressive optic neuropathy and glaucomatous optic neuropathy

Abstract

PurposeCompressive optic neuropathy (CON) can sometimes mimic glaucomatous optic neuropathy (GON), leading to inadequate management. Our purpose was to compare the macular area of patients with CON and GON to healthy controls (HC) and to determine if the macula area was able to distinguish between CON and GON.MethodsRetrospective, observational, cross‐sectional study, enrolling 70 patients (22 patients with CON, 25 with GON and 23 HC). Subjects were matched by age (median of 61 [±11.6]), and one eye was randomly selected. Spectral‐domain optical coherence tomography (SD‐OCT) images were generated using the Spectralis® OCT device (Heidelberg, Germany). An automated algorithm was used to segment the macular retina into nine layers and evaluate the thickness of each layer in the foveal, inner, and outer Early Treatment Diabetic Retinopathy Study (ETDRS) subfield rings. Data were compared across all study groups using Kruskal‐Wallis test, followed by pairwise comparisons for each duo. The resulting p‐values were adjusted using the Bonferroni correction and significance level was set at 0.05.ResultsHC had thicker inner retinal layer (IRL) compared with GON and CON (p < 0.05). Global retinal thickness was significantly thinner in the inner superior (IS) and inner nasal (IN) subfields in CON compared with GON (p < 0.05). The IRL is thinner in CON, specifically in the inner and outer nasal subfields, compared to GON. The IN subfield was thinner in the retinal nerve fibre, ganglion cell and inner plexiform layers (IPL) in CON compared with GON (p < 0.05). No differences were found on the inner nuclear, outer plexiform, outer nuclear and outer retinal layers between groups.ConclusionsOur findings suggest that IRL is thinner in both CON and GON, and the IN subfield is specially affected in CON compared with GON. Despite not being our primary outcome, our results suggest that, compared to HC, layer neurodegeneration in both CON and GON affects mainly the inner layers and that does not extend to layers external to IPL. In conclusion, evaluation of the macular segmented layers damage, by SD‐OCT, may be a useful add‐on tool in the differential diagnosis between these two entities, when their manifestations overlap.