Conversion of Stratus optical coherence tomography (OCT) retinal thickness to Cirrus OCT values in age-related macular degeneration
- Ilse Krebs1,2,
- Stefan Hagen1,2,
- Eva Smretschnig1,
- Irene Womastek3,
- Werner Brannath3,
- Susanne Binder1,2
- 1The Ludwig Boltzmann Institute for Retinology and Biomicroscopic Laser Surgery, Vienna, Austria
- 2Department of Ophthalmology, Rudolph Foundation Clinic, Vienna, Austria
- 3Core Unit for Medical Statistics and Informatics, Medical University, Vienna, Austria
- Correspondence to Ilse Krebs, Department of Ophthalmology, Rudolf Foundation Clinic, Juchgasse 25, 1030 Vienna, Austria;
- Accepted 26 December 2010
- Published Online First 24 February 2011
Aim Spectral domain optical coherence tomography (SD OCT) is of increasing importance and is gradually replacing time domain OCT (TD OCT). Our aim was to determine a formula to convert Stratus OCT (TD OCT) to Cirrus OCT (SD OCT) retinal thickness.
Methods Central retinal thickness (CRT) and retinal volume (RV) were obtained by the macular thickness program of Stratus OCT and the cube 512×128 program of Cirrus OCT in patients with exudative age-related macular degeneration (AMD). Algorithm line failures were corrected. A linear model with Stratus OCT CRT as fixed factor and Cirrus OCT CRT as dependent variable was applied to calculate the conversion formula.
Results OCT examinations of 104 eyes of 104 patients were reviewed and corrected when necessary. Stratus and Cirrus OCT CRT were significantly correlated (p<0.0001). For CRT the formula Cirrus CRT=58.63+0.94× Stratus CRT was calculated. The correlation was significantly influenced by the height of the CRT values (p<0.0001), but not by whether correction was necessary. For RV the formula Cirrus OCT RV=3.098+0.98× Stratus OCT RV was calculated.
Conclusion Stratus OCT and Cirrus OCT use a different posterior reference line within the hyper-reflective band of the outer retina. Therefore a conversion formula is necessary to compare Stratus and Cirrus OCT CRT values, and this has been determined in our study.
- Age-related macular degeneration
- retinal thickness
- optical coherence tomography
- spectral domain OCT
- choroidal neovascularisation, retina
Competing interests None declared.
Patient consent Obtained.
Ethics approval This study was conducted with the approval of the Ethics Committee of the City of Vienna.