Comparison of retinal thickness measurements obtained by Retinal Thickness Analyzer (RTA II) and Optical Coherence Tomography (Stratus OCT) in healthy subjects.

Nunes S., Baptista P., Bernardes R., Cunha-Vaz J.

In order to compare retinal thickness using the Retinal Thickness Analyzer (RTA II) and the Optical Coherence Tomography (Stratus OCT), 34 eyes from 20 volunteers, aged from 40 to 60 years, were examined in the same session. To allow for a
direct comparison, a new retinal thickness map based on the RTA raw data was developed to produce OCT-like maps. For each area of both maps, the mean, SD and 95% CI of the mean retinal thickness were computed. Statistical significant differences, in the mean retinal thickness obtained by both techniques, were found with the Stratus OCT presenting higher retinal thickness values in all areas. The reliability of the two techniques, assed by the Intra-Class Correlation coefficient (to assess for consistency in retinal thickness measurements) and by the Cohen’s Kappa statistics (to asses for agreement between techniques), is moderate to good. For the agreement analysis we considered absolute agreement when both techniques showed the same behavior (increase or decrease over the 95% CI of the mean retinal thickness or both on the normal range), absolute disagreement when both techniques showed opposite behavior (increase/decrease or decrease/increase over the 95% CI of the mean retinal thickness), and disagreement otherwise. Best ICC consistency of data and agreement between techniques were found on the central 1 mm disc area (ICC = 0.734 and k = 0.686), where the Stratus OCT has higher density of retinal thickness measurements.

Exp. Ophthalmol. 2006, 32 (1): 13-19.

2006