Beta and Gamma Peripapillary Atrophy in Myopic Eyes With and Without Glaucoma

Abstract

PURPOSE. To determine whether beta and gamma peripapillary atrophy (PPA) areas measured with optical coherence tomography (OCT) enhances glaucoma diagnosis in myopic subjects.METHODS. We included 55 myopic glaucoma patients and 74 myopic nonglaucomatous controls. Beta-PPA comprised the area external to the clinical disc margin, with absence of retinal pigment epithelium and presence of Bruch's membrane. Gamma-PPA comprised the area external to the disc margin, with absence of both RPE and Bruch's membrane. OCT scans colocalized to fundus photographs were used to measure PPA, choroidal thickness, border tissue of Elschnig configuration, optic disc area, and optic disc ovality. 2 , respectively). However, the distributions of both beta-and gamma-PPA in the two groups overlapped widely. The areas under the receiver operating characteristic curve of beta-and gamma-PPA areas were 0.60 and 0.59, respectively. Larger beta-PPA area was associated with larger disc area, thinner choroidal thickness, longer axial length, less oblique border tissue configuration, older age, and greater disc ovality. Larger gamma-PPA area was associated with greater disc ovality, more oblique border tissue configuration, and longer axial length. RESULTS.CONCLUSIONS. Subclassifying PPA with OCT into beta and gamma zones reveals association with different covariates, but does not enhance the diagnostic performance for glaucoma in a population of predominantly Caucasians myopic subjects.

Measurements of the parapapillary atrophy zones in en face optical coherence tomography images

“…This is in line with the results of the study by Kim et al,[15] but conflicts with those of Dai et al and Vinna et al[14,18] It is quite challenging to evaluate the impact of age on the PPA zones separately from those of myopia and glaucoma, because of very strong correlation of age with both glaucoma and myopia. It is well known that older age is associated with increased risk of glaucoma.…”

“…[14,15] Recent research questioned the relevance of OCT-based PPA classification in myopic eyes, defined by the authors’ own cut-off value (-2 diopters). [18] However, the cut-off value of -8 diopters of refractive error or 26.5 mm of an axial length has been proposed for defining high myopia based on hospital-based and population based studies. [19,20] Therefore, we conducted the current research in a population without high myopia, defined by this evidence-based criteria.…”

“…For example, a recent study showed that neither the OCT-defined beta nor the gamma zone significantly correlated with glaucoma in eyes with myopia. [18] Furthermore, the association between the OCT-defined PPA zones and age remains controversial; one study showed that age positively associated with the gamma zone area,[14] whereas another study reported the association between age and the presence of the beta zone. [15]…”

“…In previous studies, areas and widths of the PPA zones were measured on the near-infrared (IR) or color fundus images. [14,15,18] The borders of the PPA zones were first identified in the B-scans, and subsequently mapped onto the corresponding near-infrared (IR) or color fundus images using simultaneous visualization. Then the areas and the lengths of the zones were measured on the corresponding fundus images.…”

Ganglion Cell-Inner Plexiform Layer, Peripapillary Retinal Nerve Fiber Layer, and Macular Thickness in Eyes with Myopicβ-Zone Parapapillary Atrophy

“…They divided the β -PPA into newly defined β -PPA, an area with intact Bruch's membrane, and γ -PPA, an area devoid of Bruch's membrane. They suggested an association of γ -PPA and myopia [30, 51]. But until now, most studies have used classic definition of the β -PPA and this study also did not classify the β -PPA [19, 23, 24, 28].…”