Quality of the threshold algorithm in age-related macular degeneration: Stratus versus Cirrus OCT

Automatically generated measurements of the retinal volume or the central retinal thickness are based on correctly set threshold lines on the retinal surface and the retinal pigment epithelium. The purpose of this study was to compare the accuracy of threshold algorithm lines of Stratus optical coherence tomography (OCT) with those of Cirrus OCT.

A consecutive series of patients at least 50 years of age with exudative age-related macular degeneration was included. Stratus OCT (retinal thickness program) and Cirrus OCT (macular cube 512 x 128) were performed by the same examiner, the sequence of the examinations was randomized. Two independent examiners evaluated the positioning of the threshold algorithm lines and performed a grading of the failures. Logistic regression analysis was applied for evaluation of the failure rate.

One hundred four patients were included. For the entire OCT examination (6 scans Stratus OCT, 128 scans Cirrus OCT) algorithm line failures were detected in 69.2% of the Stratus OCT and in 25% of the Cirrus OCT examinations, with the difference reaching statistical significance (P < 0.001). The median failure grade was 1 (0-6) for Stratus and 0 (0-5.15) for Cirrus OCT. Age, measurement sequence, and investigator did not influence the error rates.

With Cirrus OCT automatically performed and therefore objective measurements of central retinal thickness and retinal volume were provided correctly in 69.2% of the scans. Furthermore, this latest software version offers the possibility of manual correction of false positioned algorithm lines (ClinicalTrials.gov number, NCT00568191).