The invention relates to the use of photodynamic therapy to treat macular edemas, including DME, CRVO and BRVO. A device for making color measurements comprising an image-capture device, a processor or logic device, and a memory location for accumulating color data, and the processor or logic device is programmed to perform color measurements by accumulating the data for pixels located in the target area in memory, and determining a representative color value. The output includes first output corresponding to defects on the wafer and second output that does not correspond to the defects.