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Koichiro Hayashi, Kojiro Imai, Kazuhiko Mori, Yoko Ikeda, Morio Ueno, Yuko Maruyama, Yuji Yamamoto, Shigeru Kinoshita; Ocular structural differences between eyes with parapapillary atrophy β and γ in non-glaucoma subjects. Invest. Ophthalmol. Vis. Sci. 2016;57(12):874.
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© ARVO (1962-2015); The Authors (2016-present)
Glaucoma is a multifactorial disease comprising factors such as intraocular pressure (IOP) and the other factors, such as parapapillary atrophy (PPA). The parapapillary zone in which the Bruch’s membrane and retinal pigment epithelium are both deleted is known as gamma (γ)-zone PPA (γPPA), and that in which the deletion of retinal pigment epithelium is isolated is known as beta (β)-zone PPA (βPPA). According to previous reports, βPPA is associated with glaucoma, whereas γPPA is associated with myopia. Elucidating the ocular structural parameters of eyes with βPPA at the non-glaucoma stage provides clues as to the underlying cause of glaucoma. The purpose of this study was to examine the ocular structural parameters of βPPA eyes compared to γPPA eyes.
This observational study involved 51 non-glaucoma subjects (12 males and 39 females; mean age: 65.0±6.2 years) without visual field defects examined at the Kyoto Prefectural University of Medicine Hospital, Kyoto, Japan. PPA was distinguished by means of a horizontal B-scan passed through the center of the optic disc using spectral domain optical coherence tomography (OCT). Only eyes with βPPA or γPPA were included. Structural parameters such as anterior chamber depth, axial length, corneal thickness, spherical equivalent, angle, IOP, disc area, cup area, 8 areas of the retinal nerve fiber layer (RNFL), average RNFL, and Bruch’s membrane opening-minimum rim width (BMO-MRW) at temporal region were collected using an IOL-master®, HRT2®, anterior segment OCT, Scheimpflug camera, and spectral domain OCT. Subjects with missing data or faint images were excluded from the study. Parameters of βPPA group and γPPA group were then compared using the non-paired t test.
The βPPA group involved 35 eyes of 29 subjects, and the γPPA group involved 26 eyes of 22 subjects. Nasal upper part of RNFL was significantly thinner in the βPPA group than in the γPPA group (72.8μm and 79.3μm, respectively) (p<0.05). BMO-MRW was thinner in the βPPA group than in the γPPA group (176.9μm and 207.0μm, respectively) (p<0.01).
NU and BMO-MRW were thin in βPPA eyes, thus possibly suggesting that βPPA is a sign of optic disc fragility even in non-glaucoma eyes.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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