Thomas Callan

Comparing retinal thickness measurements from cirrus spectral domain- and stratus time domain-optical coherence tomography

Purpose: The purpose of this study was to compare retinal measurements obtained using spectral domain-optical coherence tomography with measurements obtained using time domain-optical coherence tomography. Methods: Three hundred and seventy subjects were recruited at three university-based and one community-based retina practice for a cross-sectional observational study. For each subject, one eye was enrolled as the study eye. A Stratus Fast Macular scan was performed, and a Cirrus 200 × 200 Macular Cube scan was performed. Both instruments segment the acquired images to generate retinal thickness values and report averages measured in nine subfields defined by the Early Treatment Diabetic Retinopathy Study. These average values were compared with each other quantitatively using linear regression and Bland-Altman plots. Results: Of the recruited subjects, 283 had acceptable images taken on the same day with both the Cirrus and Stratus devices. Mean differences between the instruments were noted in all subfields for all disease categories and ranged from 29 &mgr;m (outer superior subfield) to 54 &mgr;m (central subfield). Conclusion: Differences between time domain and spectral domain measurements of retinal thickness depend on pathology and location. Comparisons across instruments should be made with caution.

A new SITA perimetric threshold testing algorithm; construction and a multi-center clinical study

PURPOSE To describe a new time-saving threshold visual field-testing strategy-Swedish Interactive Thresholding Algorithm (SITA) Faster, which is intended to replace SITA Fast-and to report on a clinical evaluation of this new strategy. DESIGN Description and validity analysis for modifications applied to SITA Fast. METHODS Five centers tested 1 eye of each of 126 glaucoma and glaucoma suspect patients with SITA Faster, SITA Fast, and SITA Standard at each of 2 visits. Outcomes included test time, mean deviation, and the visual field index (VFI), significant test points in probability maps, and intertest threshold variability. RESULTS Mean (standard deviation) test times were 171.9 (45.3) seconds for SITA Faster, 247.0 (56.7) for SITA Fast, and 369.5 (64.5) for SITA Standard (P < .001). SITA Faster test times averaged 30.4 % shorter than SITA Fast and 53.5 % shorter than SITA Standard. Mean deviation was similar among all 3 tests.VFI did not differ between SITA Fast and SITA Faster tests, mean difference 0%, but VFI values were 1.2% lower with SITA Standard compared to both SITA Fast (P = .007) and SITA Faster (P = .002). A similar trend was seen with a slightly higher number of significant test points with SITA Standard than with SITA Fast and SITA Faster. All 3 tests had similar test-retest variability over the entire range of threshold values. CONCLUSIONS SITA Faster saved considerable test time. SITA Faster and SITA Fast gave almost identical results. There were small differences between SITA Faster and SITA Standard, of the same character as previously shown for SITA Fast vs SITA Standard.