Backgrounds/aims To evaluate the agreement of parapapillary retinal nerve fibre layer (RNFL) thickness among three spectral-domain optical coherence tomography (OCT) instruments.
Methods Two hundred and three glaucomatous eyes and 88 normal eyes were imaged by Cirrus, RTVue and 3D OCT. The average and the four quadrant RNFL thicknesses were evaluated. Agreement among RNFL measurements was evaluated using Bland–Altman analysis and linear regression analysis. The percentage of each quadrant in the average RNFL thickness value was compared among the three instruments.
Results Cirrus showed significantly smaller thickness values than RTVue (difference=8.8 μm, p<0.0001) and 3D OCT (difference=8.1 μm, p<0.0001). Although RNFL measurements among the instruments were highly correlated, the Bland–Altman analysis revealed proportional biases for most of the pair-wise agreements. Additionally, 3D OCT showed strong proportional biases with RTVue and 3D OCT. RTVue had a smaller occupied proportion of nasal quadrants (30.2%) and a larger proportion of inferior quadrants (32.4%) compared with Cirrus and 3D OCT.
Conclusions RNFL measurements among the instruments were well correlated but had different values for thickness. The measurement circle of RTVue might be more superior-temporally located compared with the other instruments. Differences in the measurement protocols might be affected by the disagreements. These instruments should not be used interchangeably.
- Spectral-domain optical coherence tomography
- retinal nerve fibre layer thickness
- Bland–Altman analysis
- experimental and animal models
- intraocular pressure
- diagnostic tests/investigation
- experimental and laboratory
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Funding Supported by Grant-in-Aid 22390324 (AN, YY, MN), 20592043 (AK, MN, AN) and 23791983 (AK) for scientific research by the Ministry of Education, Culture, Sports, and Science and Technology of the Japanese government, and Suda Memorial Foundation (AK).
Competing interests None.
Patient consent Obtained.
Ethics approval The study protocol was approved by the Institutional Review Board of Kobe University and adhered to the tenets of the Declaration of Helsinki.
Provenance and peer review Not commissioned; externally peer reviewed.