Br J Ophthalmol 93:775-781 doi:10.1136/bjo.2008.150698
  • Clinical science
    • Original Article

Agreement between spectral-domain and time-domain OCT for measuring RNFL thickness

  1. G Vizzeri,
  2. R N Weinreb,
  3. A O Gonzalez-Garcia,
  4. C Bowd,
  5. F A Medeiros,
  6. P A Sample,
  7. L M Zangwill
  1. Hamilton Glaucoma Center, Department of Ophthalmology, University of California San Diego, La Jolla, California, USA
  1. Dr L M Zangwill, Hamilton Glaucoma Center, Department of Ophthalmology, University of California San Diego, La Jolla, CA, USA, 9500 Gilman Drive #0946, La Jolla, CA 92093-0946, USA; zangwill{at}
  • Accepted 28 December 2008
  • Published Online First 19 March 2009


Background/aims: To evaluate spectral-domain (SD) optical coherence tomography (OCT) reproducibility and assess the agreement between SD-OCT and Time-Domain (TD) OCT retinal nerve fibre layer (RNFL) measurements.

Methods: Three Cirrus-SD-OCT scans and one Stratus-TD-OCT scan were obtained from Diagnostic Innovations in Glaucoma Study (DIGS) healthy participants and glaucoma patients on the same day. Repeatability was evaluated using Sw (within-subject standard deviation), CV (coefficient of variation) and ICC (intraclass correlation coefficient). Agreement was assessed using correlation and Bland–Altman plots.

Results: 16 healthy participants (32 eyes) and 39 patients (78 eyes) were included. SD-OCT reproducibility was excellent in both groups. The CV and ICC for Average RNFL thickness were 1.5% and 0.96, respectively, in healthy eyes and 1.6% and 0.98, respectively, in patient eyes. Correlations between RNFL parameters were strong, particularly for average RNFL thickness (R2 = 0.92 in patient eyes). Bland–Altman plots showed good agreement between instruments, with better agreement for average RNFL thickness than for sectoral RNFL parameters (for example, at 90 µm average RNFL thickness, 95% limits of agreement were −13.1 to 0.9 for healthy eyes and −16.2 to −0.3 µm for patient eyes).

Conclusions: SD-OCT measurements were highly repeatable in healthy and patient eyes. Although the agreement between instruments was good, TD-OCT provided thicker RNFL measurements than SD-OCT. Measurements with these instruments should not be considered interchangeable.


  • Competing interests: Carl Zeiss Meditec: FAM (F, R), PAS (F), RNW (F,C), LMZ (F). Haag-Streit: PAS (F). Heidelberg Engineering: FAM (F), RNW (F), LMZ (F). Lace Elettronica: CB (F). Optovue: LMZ (F). Pfizer: CB (F). Reichert Instruments: FAM (R). Welch-Allyn: PAS (F).

  • Funding: NIH EY011008, NIH EY008208 and participant incentive grants in the form of glaucoma medication at no cost from Alcon Laboratories, Allergan, Pfizer and SANTEN.

  • Ethics approval: Ethics approval was provided by University of California San Diego Institutional Review Board.

  • Patient consent: Obtained.

Relevant Article

Register for free content

Free sample
This recent issue is free to all users to allow everyone the opportunity to see the full scope and typical content of BJO.
View free sample issue >>

Don't forget to sign up for content alerts so you keep up to date with all the articles as they are published.

Navigate This Article