title: Correlation of structural retinal nerve fibre layer parameters and functional measures using Heidelberg Retinal Tomography and Spectralis spectral domain optical coherence tomography at different levels of glaucoma severity.
abstract: BACKGROUND
  To compare the structure/function relationship in glaucoma cases at different levels of severity, and with different disc sizes, between the Heidelberg Retinal Tomography and Spectralis spectral domain optical coherence tomography.
  
  
  METHODS
  Retrospective study of glaucoma patients attending a Sydney-based private practice.
  
  
  METHODS
  169 eyes of 169 patients with a clinical diagnosis of glaucoma.
  
  
  METHODS
  Patients were divided on visual field criteria into early (mean deviation > -4 dB), moderate (-4 dB < mean deviation < -10 dB) and severe (mean deviation < -10 dB) disease. Bivariate correlation (Spearman's rho) between mean threshold scores for each area and the corresponding mean retinal nerve fibre layer thickness sectoral measurement were calculated.
  
  
  METHODS
  Correlation, as measured by Spearman's rho, between retinal nerve fibre layer measurements and mean threshold scores. Comparison of correlation strengths between the two scanning modalities with analysis of the effect of disease severity and disc size.
  
  
  RESULTS
  Both imaging techniques showed only moderate correlations at best. Spectral domain optical coherence tomography (global retinal nerve fibre layer Spearman's rho = 0.670, P < 0.01) had higher correlation coefficients compared with Heidelberg Retinal Tomography rim area (Spearman's rho = 0.449, P < 0.01) and retinal nerve fibre layer (Spearman's rho = 0.421, P < 0.01). Disc size did not have a significant influence on the structure/function relationship.
  
  
  CONCLUSIONS
  Spectral domain optical coherence tomography retinal nerve fibre layer measurements demonstrated closer correlations to visual field threshold reductions using a structure/function model in varying stages of glaucoma.
authors.affiliation: Australian School of Advanced Medicine, Department of Ophthalmology and Visual Science, Macquarie University, Sydney, New South Wales, Australia. john.leaney@students.mq.edu.au
authors.forename: John
authors.initials: J
authors.lastname: Leaney
authors.forename: Paul R
authors.initials: PR
authors.lastname: Healey
authors.forename: Martin
authors.initials: M
authors.lastname: Lee
authors.forename: Stuart L
authors.initials: SL
authors.lastname: Graham
mesh_terms: D000368:Aged; D003941:Diagnostic Techniques, Ophthalmological; D018450:Disease Progression; D005902:Glaucoma, Open-Angle / Q000175:diagnosis* / Q000503:physiopathology; D006801:Humans; D007429:Intraocular Pressure; D007834:Lasers; D009412:Nerve Fibers / Q000473:pathology*; D009887:Ophthalmoscopy; D009898:Optic Disk / Q000473:pathology*; D009901:Optic Nerve Diseases / Q000175:diagnosis* / Q000503:physiopathology; D012165:Retinal Ganglion Cells / Q000473:pathology*; D012189:Retrospective Studies; D012684:Sensory Thresholds / Q000502:physiology; D012720:Severity of Illness Index; D041623:Tomography, Optical Coherence; D014065:Tonometry, Ocular; D014794:Visual Fields / Q000502:physiology*