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 x 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 microm (outer superior subfield) to 54 microm (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.

Validation of the UNC OCT Index for the Diagnosis of Early Glaucoma.

PURPOSE: To independently validate the performance of the University of North Carolina Optical Coherence Tomography (UNC OCT) Index in diagnosing and predicting early glaucoma. METHODS: Data of 118 normal subjects (118 eyes) and 96 subjects (96 eyes) with early glaucoma defined as visual field mean deviation (MD) greater than -4 decibels (dB), aged 40 to 80 years, and who were enrolled in the Full-Threshold Testing Size III, V, VI comparison study were used in this study. CIRRUS OCT average and quadrants' retinal nerve fiber layer (RNFL); optic disc vertical cup-to-disc ratio (VCDR), cup-to-disc area ratio, and rim area; and average, minimum, and six sectoral ganglion cell-inner plexiform layer (GCIPL) measurements were run through the UNC OCT Index algorithm. Area under the receiver operating characteristic curve (AUC) and sensitivities at 95% and 99% specificity were calculated and compared between single parameters and the UNC OCT Index. RESULTS: Mean age was 60.1 ± 11.0 years for normal subjects and 66.5 ± 8.1 years for glaucoma patients (P < 0.001). MD was 0.29 ± 1.04 dB and -1.30 ± 1.35 dB in normal and glaucomatous eyes (P < 0.001), respectively. The AUC of the UNC OCT Index was 0.96. The best single metrics when compared to the UNC OCT Index were VCDR (0.93, P = 0.054), average RNFL (0.92, P = 0.014), and minimum GCIPL (0.91, P = 0.009). The sensitivities at 95% and 99% specificity were 85.4% and 76.0% (UNC OCT Index), 71.9% and 62.5% (VCDR, all P < 0.001), 64.6% and 53.1% (average RNFL, all P < 0.001), and 66.7% and 58.3% (minimum GCIPL, all P < 0.001), respectively. CONCLUSIONS: The findings confirm that the UNC OCT Index may provide improved diagnostic perforce over that of single OCT parameters and may be a good tool for detection of early glaucoma. TRANSLATIONAL RELEVANCE: The UNC OCT Index algorithm may be incorporated easily into routine clinical practice and be useful for detecting early glaucoma.