Transitioning from stratus OCT to cirrus OCT: a comparison and a proposed equation to convert central subfield macular thickness measurements in healthy subjects
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The purpose of this paper is to study the differences between central subfield macular thickness (CSMT) measurements obtained by time-domain Stratus optical coherence tomography (OCT) and Cirrus spectral domain OCT (Carl Zeiss Meditec, Dublin, CA) and to formulate an equation to convert CSMT values from one to the other.
CSMT were measured by both Stratus Macula OCT and Cirrus Macula OCT in 46 healthy subjects. Agreement between measurements was calculated using Lin’s concordance coefficient.
The average age of our group was 30 with the logMAR visual acuity of −0.015. The Stratus CSMT measurement (mean ± standard deviation) 193.91 ± 21.7 was statistically significant from the Cirrus CSMT measurement 252.82 ± 28.4 (p < 0.001). The transformation equation 0.76×−0.51 from Cirrus to Stratus resulted in values that best agreed with the observed Stratus OCT values.
We identified a significant difference of CSMT measurements between Stratus and Cirrus. The Cirrus typically gave a higher value of CSMT. We derived a linear equation to convert the measurements from Cirrus to Stratus which resulted in transformed values that concord with the observed Stratus OCT values.
KeywordsCentral subfield macular thickness (CSMT) Time domain stratus OCT Spectral domain cirrus OCT Refractive error Linear transformation Lin’s concordance coefficient
The authors would like to thank Mr. Mark Houston for providing the OCT imaging.
None of the authors have any financial interests to disclose.
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