The SCORE Study is one of the largest multicenter studies in RVO since the Central Vein Occlusion Study and Branch Vein Occlusion Study6
and provides an excellent opportunity to evaluate in detail the fundus and fluorescein angiography features in RVO. This article describes the procedures and reproducibility of evaluating stereoscopic color fundus photographs and fluorescein angiograms developed for the assessment of RVO features in the SCORE Study. The features graded on color fundus photographs and fluorescein angiograms are important outcome measures in the SCORE Study.
The temporal reproducibility exercises evaluate the reproducibility of a reserved sample of images throughout the course of a study (similar to a laboratory calibration). These exercises help identify fluctuations in the grading methodology over the years of a clinical trial owing to changes in grading personnel, changes in technology, and experience gained over the course of the study. On the other hand, contemporaneous reproducibility gives immediate feedback regarding grader performance.
Agreement on the type of RVO at baseline by trained nonphysician graders using the definitions developed for the SCORE Study shows excellent temporal reproducibility (93%–96%) during 3 years. In addition, the graders are in good agreement (92%) with ophthalmologists’ classification of RVO.7
The temporal reproducibility is also excellent for the detection of presence of retinal thickening (96%–98%) and is moderate (>0.4 to <0.75) for determining the area of retinal thickening (ICC, 0.39–0.64). As shown in and , the area of thickening in the yearly regrades showed a larger area in all 3 annual regrades compared with the original grade. However, the means () are within the grading margin of error. The SCORE graders were all experienced in evaluating diabetic macular edema, which tends to have focal areas of retinal thickening, whereas areas of thickening among RVO eyes are typically larger and more diffuse. We speculate that the SCORE Study graders may have initially been conservative in grading the area of retinal thickening in all eyes. Experience over the course of the study changed the approach to grading RVO to include larger areas of edema, especially for the acute phase of RVO.
Assessment of retinal thickening using color fundus photographs requires good stereoscopic images, since thickening is identified by retinal elevation with or without partial loss of transparency.4
Use of an integrated approach in which color fundus photographs are graded concurrently with optical coherence tomographic images may improve reproducibility for evaluation of retinal thickening.8
This procedure was not used in the SCORE Study in which fundus photographs and optical coherence tomographic images were evaluated separately.
In the SCORE Study, agreement on area of retinal hemorrhages on color fundus photographs showed excellent reproducibility (0.87–0.96). Although easy to detect in acute cases of RVO, resolving hemorrhages are often difficult to distinguish from the background choroidal pattern in less acute cases. Image quality, especially red saturation, can interfere with detection of hemorrhages. In the digital environment, adjusting the color and tonal balance (optimization) of images removes some of the image quality–related issues and may improve the reproducibility further.9
Most eyes in the temporal drift sample did not have capillary nonperfusion on fluorescein angiography. Temporal reproducibility was excellent in the few eyes that had minimal capillary nonperfusion. Reproducibility of fluorescein leakage is moderate with area of leakage consistently larger on all annual regrades. Detection of fluorescein leakage can be difficult owing to the indistinct borders of the area of leakage and the strong influence of photograph quality.
The SCORE Study grading system for RVO provides clear definitions and evaluation methodology for color fundus photographs and fluorescein angiograms. The SCORE Study grading system provides morphologic characterization of the disease in terms of the type of RVO and the area of retinal thickening, retinal hemorrhage, fluorescein leakage, and capillary nonperfusion. A systematic temporal drift occurred in evaluating area of retinal thickening as the reading center gained experience in grading RVO studies. Overall, the reproducibility and quality-control exercises performed in the SCORE Study grading system demonstrate the reliability of assessment of RVO with color fundus photographs and fluorescein angiography. The SCORE Study grading system is reproducible and can be used for future multicenter longitudinal studies of RVO.