title: Importance of Normal Aging in Estimating the Rate of Glaucomatous Neuroretinal Rim and Retinal Nerve Fiber Layer Loss.
abstract: OBJECTIVE
  To describe longitudinal rates of change of neuroretinal parameters in patients with glaucoma and healthy controls, and to evaluate the influence of covariates.
  
  
  METHODS
  Prospective longitudinal study.
  
  
  METHODS
  Treated patients with glaucoma (n = 192) and healthy controls (n = 37).
  
  
  METHODS
  Global disc margin-based neuroretinal rim area (DMRA) was measured with confocal scanning laser tomography, while Bruch's membrane opening-minimum rim width (BMO-MRW), BMO area (BMOA), and peripapillary retinal nerve fiber layer thickness (RNFLT) were measured with optical coherence tomography at 6-month intervals. Individual rates of change were estimated with ordinary least-squares regression, and linear mixed effects modeling was used to estimate the average rate of change and differences between the groups, and to evaluate the effects of baseline measurement and baseline age on rates of change.
  
  
  METHODS
  Rates of change for each parameter.
  
  
  RESULTS
  Subjects were followed for a median (range) of 4 (2-6) years. The proportion of controls who had significant reduction of neuroretinal parameters was 35% for BMO-MRW, 31% for RNFLT, and 11% for DMRA. The corresponding figures for patients with glaucoma were not statistically different (42%, P = 0.45; 31%, P = 0.99; 14%, P = 0.99, respectively). Controls had a significant reduction of BMO-MRW (mean: -1.92 μm/year, P < 0.01) and RNFLT (mean: -0.44 μm/year, P = 0.01), but not DMRA (mean: -0.22×10(-2) mm(2)/year, P = 0.41). After adjusting for covariates, patients with glaucoma had faster, but not statistically different, rates of deterioration compared with controls, by -1.26 μm/year (P = 0.07) for BMO-MRW, -0.40 μm/year (P = 0.11) for RNFLT, and -0.38×10(-2) mm(2)/year (P = 0.23) for DMRA. Baseline BMO-MRW and RNFLT significantly influenced the respective rates of change, with higher baseline values relating to faster reductions. Older age at baseline was associated with a slower reduction in rates of BMO-MRW. Reductions in intraocular pressure were related to increases in BMO-MRW and DMRA. There was a tendency for BMOA to decrease over time (-0.38×10(-2) mm(2)/year; P = 0.04).
  
  
  CONCLUSIONS
  Age-related loss of neuroretinal parameters may explain a large proportion of the deterioration observed in treated patients with glaucoma and should be carefully considered in estimating rates of change.
authors.affiliation: Department of Ophthalmology and Visual Sciences, Dalhousie University, Halifax, Nova Scotia, Canada.
authors.forename: Jayme R
authors.initials: JR
authors.lastname: Vianna
authors.affiliation: Department of Ophthalmology and Visual Sciences, Dalhousie University, Halifax, Nova Scotia, Canada.
authors.forename: Vishva M
authors.initials: VM
authors.lastname: Danthurebandara
authors.affiliation: Department of Ophthalmology and Visual Sciences, Dalhousie University, Halifax, Nova Scotia, Canada.
authors.forename: Glen P
authors.initials: GP
authors.lastname: Sharpe
authors.affiliation: Department of Ophthalmology and Visual Sciences, Dalhousie University, Halifax, Nova Scotia, Canada.
authors.forename: Donna M
authors.initials: DM
authors.lastname: Hutchison
authors.affiliation: Department of Ophthalmology and Visual Sciences, Dalhousie University, Halifax, Nova Scotia, Canada.
authors.forename: Anne C
authors.initials: AC
authors.lastname: Belliveau
authors.affiliation: Department of Ophthalmology and Visual Sciences, Dalhousie University, Halifax, Nova Scotia, Canada.
authors.forename: Lesya M
authors.initials: LM
authors.lastname: Shuba
authors.affiliation: Department of Ophthalmology and Visual Sciences, Dalhousie University, Halifax, Nova Scotia, Canada.
authors.forename: Marcelo T
authors.initials: MT
authors.lastname: Nicolela
authors.affiliation: Department of Ophthalmology and Visual Sciences, Dalhousie University, Halifax, Nova Scotia, Canada. Electronic address: bal@dal.ca.
authors.forename: Balwantray C
authors.initials: BC
authors.lastname: Chauhan
mesh_terms: D000368:Aged; D000375:Aging / Q000502:physiology*; D005260:Female; D005500:Follow-Up Studies; D005902:Glaucoma, Open-Angle / Q000503:physiopathology* / Q000601:surgery; D064368:Healthy Volunteers; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology; D008297:Male; D018613:Microscopy, Confocal; D008875:Middle Aged; D009412:Nerve Fibers / Q000473:pathology*; D009898:Optic Disk / Q000473:pathology*; D009901:Optic Nerve Diseases / Q000503:physiopathology* / Q000601:surgery; D011446:Prospective Studies; D012165:Retinal Ganglion Cells / Q000473:pathology*; D041623:Tomography, Optical Coherence; D058609:Visual Field Tests