Correlations between the optic nerve head morphology and ocular biometrics in highly myopic eyes

AIM: To analyze peripapillary atrophy β/γ zone (PPA-β/γ) and the optic disc ovality index, and to assess their associations with the axial length (AL), refractive error, best corrected visual acuity (BCVA), choroidal thickness (CT), and age in highly myopic eyes. METHODS: This was a retrospective observational case series. The study included 667 patients consecutively examined for highly myopic eyes [spherical equivalent ≤-6.0 diopters (D) and AL≥26 mm] with or without myopic retinopathy. Each patient went through a comprehensive ophthalmological examination that included spectral domain optical coherence tomography (SD-OCT) of the macula, A-mode ultrasonography, and a cycloplegic refraction test. The ovality index and PPA-β/γ area were measured from optic disc photographs. RESULTS: A significant association was seen between PPA-β/γ area and the ovality index (P=0.000, r=-0.232). The PPA-β/γ area increased significantly with a longer AL, older age, worse BCVA, higher refractive error, and thinner choroid (P<0.01). The oval disc was significantly correlated with a longer AL, older age, worse BCVA, higher refractive error, larger PPA-β/γ area, and thinner choroid (P<0.01). CONCLUSION: The PPA-β/γ zone and ovality index in highly myopic eyes show distinct associations with the AL, refractive error, BCVA, age, and CT.