title: Microstructure of β-zone parapapillary atrophy and rate of retinal nerve fiber layer thinning in primary open-angle glaucoma.
abstract: OBJECTIVE
  To investigate whether the rate of retinal nerve fiber layer (RNFL) thinning differs according to the microstructure of β-zone parapapillary atrophy (PPA) as evaluated by spectral-domain (SD) optical coherence tomography (OCT) in primary open-angle glaucoma (POAG).
  
  
  METHODS
  Prospective, observational, comparative study.
  
  
  METHODS
  A total of 195 eyes with POAG that had been evaluated by serial SD-OCT RNFL thickness measurements for ≥ 2 years.
  
  
  METHODS
  On the basis of the extent of Bruch's membrane (BM) within the β-zone PPA (area without retinal pigment epithelium [RPE]), as shown in the infrared fundus images, PPA was divided into PPA+BM (PPA with intact BM) and PPA-BM (PPA devoid of BM). Eyes were categorized into group A (having PPA+BM only, n=64), group B (having both PPA+BM and PPA-BM, n=58), group C (having PPA-BM only, n=32), and group D (without β-zone PPA, n=41). The rate of progressive OCT RNFL thinning was determined by linear regression and compared between groups. Factors influencing the rate of RNFL thinning were evaluated, including age, sex, follow-up duration, history of filtering surgery, baseline RNFL thickness, baseline intraocular pressure (IOP), mean IOP and IOP fluctuation during follow-up, PPA types, baseline PPA width, PPA width increase, axial length (AXL), central corneal thickness, and visual field mean deviation (MD).
  
  
  METHODS
  Rate of thinning of OCT RNFL thicknesses over time.
  
  
  RESULTS
  Patients in groups B and C were significantly younger and more myopic, and had a greater AXL, than those in groups A and D (all P<0.001). The rate of global RNFL thinning was significantly faster in group A (-1.66 ± 2.94 μm/year) than in the other groups (group B, -0.87 ± 1.28 μm/year; group C, 0.20 ± 1.86 μm/year; group D, -0.28 ± 1.74 μm/year; P = 0.001). Multivariate regression showed a significant association of shorter follow-up period (P = 0.016), greater baseline global RNFL thickness (P = 0.035), type of β-zone PPA (group A, P = 0.023), and greater baseline PPA+BM width (P = 0.034) with a faster rate of RNFL thinning.
  
  
  CONCLUSIONS
  The rate of RNFL thinning differed according to the microstructure of β-zone PPA. It was faster for eyes with β-zone PPA with intact BM than for eyes without β-zone PPA or with β-zone PPA devoid of BM.
authors.affiliation: Department of Ophthalmology, Seoul National University College of Medicine, Seoul National University Hospital, Seoul, Korea.
authors.forename: Yong Woo
authors.initials: YW
authors.lastname: Kim
authors.affiliation: Department of Ophthalmology, Seoul National University College of Medicine, Seoul National University Bundang Hospital, Seongnam, Korea. Electronic address: opticdisc@gmail.com.
authors.forename: Eun Ji
authors.initials: EJ
authors.lastname: Lee
authors.affiliation: Department of Ophthalmology, Seoul National University College of Medicine, Seoul National University Bundang Hospital, Seongnam, Korea.
authors.forename: Tae-Woo
authors.initials: TW
authors.lastname: Kim
authors.affiliation: Department of Ophthalmology, Seoul National University College of Medicine, Seoul National University Bundang Hospital, Seongnam, Korea.
authors.forename: Mijin
authors.initials: M
authors.lastname: Kim
authors.affiliation: Department of Applied Statistics, Yonsei University, Seoul, Korea.
authors.forename: Hyunjoong
authors.initials: H
authors.lastname: Kim
mesh_terms: D000328:Adult; D018450:Disease Progression; D005260:Female; D005902:Glaucoma, Open-Angle / Q000175:diagnosis*; D006801:Humans; D007429:Intraocular Pressure; D008297:Male; D008875:Middle Aged; D009412:Nerve Fibers / Q000473:pathology*; D009896:Optic Atrophy / Q000175:diagnosis*; D009898:Optic Disk / Q000473:pathology*; D011446:Prospective Studies; D012165:Retinal Ganglion Cells / Q000473:pathology*; D041623:Tomography, Optical Coherence; D014065:Tonometry, Ocular