title: Evaluation of retinal nerve fiber layer progression in glaucoma: a comparison between the fast and the regular retinal nerve fiber layer scans.
abstract: OBJECTIVE
  To compare the performance of the fast (256 A-scans in each scan circle) and the regular (512 A-scans in each scan circle) retinal nerve fiber layer (RNFL) scan protocols for detection of glaucoma progression using the Stratus optical coherence tomography (OCT) device (Carl Zeiss Meditec, Dublin, CA).
  
  
  METHODS
  Retrospective, longitudinal study.
  
  
  METHODS
  One hundred twenty-nine eyes from 72 glaucoma patients.
  
  
  METHODS
  All patients had been followed up for 2.9 to 6.1 years with a median follow-up of 4 months. All eyes had at least 4 serial RNFL measurements obtained with both the fast and the regular RNFL scans. Visual field (VF) assessment was performed on the same day as RNFL imaging. Retinal nerve fiber layer thickness and VF progression were evaluated with linear regression analysis against age. The mean rate of average RNFL thickness reduction was estimated with linear mixed modeling.
  
  
  METHODS
  The agreement of progression detection and the rate of change of RNFL thicknesses.
  
  
  RESULTS
  A total of 1373 fast and 1373 regular RNFL scans and 1236 VF tests were analyzed. With reference to the average RNFL thickness, the fast RNFL scan detected more eyes with progression (21 eyes from 19 patients vs. 15 eyes from 13 patients) than the regular scan at a comparable level of specificity (96.9% vs. 96.1%). More eyes were found to have increasing RNFL thickness with age at individual clock hours (except for 3, 5, 6, and 11 o'clock) when the measurements were obtained with the regular scan. The agreement between the fast and the regular scan for detection of RNFL progression was fair to moderate, with κ values ranging between 0.14 and 0.49. The rate of average RNFL thickness progression was -1.01 μm per year for the fast RNFL scan and -0.77 μm per year for the regular scan.
  
  
  CONCLUSIONS
  The choice of scan protocols in the Stratus OCT has a significant impact in the evaluation of RNFL progression. The fast RNFL scan seems to be preferable to follow RNFL damage in glaucoma.
authors.affiliation: Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, Hong Kong, People's Republic of China. tlims00@hotmail.com
authors.forename: Christopher Kai-Shun
authors.initials: CK
authors.lastname: Leung
authors.forename: Carol Yim-Lui
authors.initials: CY
authors.lastname: Cheung
authors.forename: Robert Neal
authors.initials: RN
authors.lastname: Weinreb
authors.forename: Shu
authors.initials: S
authors.lastname: Liu
authors.forename: Cong
authors.initials: C
authors.lastname: Ye
authors.forename: Gilda
authors.initials: G
authors.lastname: Lai
authors.forename: Nancy
authors.initials: N
authors.lastname: Liu
authors.forename: Chi Pui
authors.initials: CP
authors.lastname: Pang
authors.forename: Kwok Kay
authors.initials: KK
authors.lastname: Tse
authors.forename: Dennis Shun Chiu
authors.initials: DS
authors.lastname: Lam
mesh_terms: D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D005901:Glaucoma / Q000175:diagnosis*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009412:Nerve Fibers / Q000473:pathology*; D009898:Optic Disk / Q000473:pathology*; D009901:Optic Nerve Diseases / Q000175:diagnosis*; D012029:Refraction, Ocular / Q000502:physiology; D015203:Reproducibility of Results; D012165:Retinal Ganglion Cells / Q000473:pathology*; D012189:Retrospective Studies; D041623:Tomography, Optical Coherence / Q000295:instrumentation / Q000379:methods*; D014792:Visual Acuity / Q000502:physiology; D014794:Visual Fields / Q000502:physiology