Method of Quantifying Size of Retinal Hemorrhages in Eyes with Branch Retinal Vein Occlusion Using 14-Square Grid: Interrater and Intrarater Reliability

Figure 1

Method of determining the area occupied by a retinal hemorrhage in a fundus photograph using a grid with 14 squares. First, a grid with 14 squares (a) is created by the PowerPoint (PPT) software (a). Each square is numbered starting at the top left (b). Next, a fundus photograph of BRVO was downloaded into a PPT file, and the grid with 14 squares was laid over the fundus photograph. The grid was enlarged or reduced so that one side of a square grid (the length of the line BA) would match the horizontal diameter of the optic disc (c). Then, the point A on the grid was placed at the temporal edge of the optic disc (d). Then, retina specialists (raters) visually estimated what percent of the area of each of the 14 squares was occupied by the retinal hemorrhage. This relative size ranged from 0 to 100% in increments of 5% (e). The total was averaged to yield the size of the hemorrhage as a percent of the entire grid. To determine the effectiveness of using the grid, an empty box of the same size as the grid was created (f), and this box was laid over a fundus photograph in the same way.

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