title: Symmetry between the right and left eyes of the normal retinal nerve fiber layer measured with optical coherence tomography (an AOS thesis).
abstract: OBJECTIVE
  To determine the limits of the normal amount of interocular symmetry in retinal nerve fiber layer (RNFL) thickness measurements obtained with third-generation time domain optical coherence tomography (OCT3).
  
  
  METHODS
  Both eyes of normal volunteers were scanned using the peripapillary standard and fast RNFL algorithms of OCT3.
  
  
  RESULTS
  A total of 108 volunteers were included in the analysis. The mean +/- standard deviation (SD) of age of the volunteers was 46.0 +/- 15.0 years (range 20-82). Forty-two participants (39%) were male and 66 (61%) were female. Mean RNFL thickness correlated extremely well, with intraclass correlation coefficients of 0.89 for both algorithms (95% confidence interval [CI], 0.84-0.93). The mean RNFL thickness of the right eye measured 1.3 mum thicker than the left on the standard scan (SD 4.7, 95% CI 0.4-2.2, P = .004) and 1.2 mum on the fast scan (SD 5.2, 95% CI 0.1-2.2, P = .026). The 95% tolerance limits on the difference between the mean RNFL thicknesses of right minus left eye was -10.8 and +8.9 mum with the standard scan algorithm and -10.6 and +11.7 mum with the fast scan algorithm.
  
  
  CONCLUSIONS
  Mean RNFL thickness between the 2 eyes of normal individuals should not differ by more than approximately 9 to 12 mum, depending on which scanning algorithm of OCT3 is used and which eye measures thicker. Differences beyond this level suggest statistically abnormal asymmetry, which may represent early glaucomatous optic neuropathy.
authors.affiliation: Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami Florida, USA.
authors.forename: Donald L
authors.initials: DL
authors.lastname: Budenz
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D001369:Axons / Q000473:pathology*; D005260:Female; D007839:Functional Laterality; D005901:Glaucoma / Q000175:diagnosis*; D006801:Humans; D007429:Intraocular Pressure; D008297:Male; D008875:Middle Aged; D009901:Optic Nerve Diseases / Q000175:diagnosis*; D012165:Retinal Ganglion Cells / Q000473:pathology*; D041623:Tomography, Optical Coherence / Q000379:methods*; D014794:Visual Fields