We have developed a technique of detecting and recording iris transillumination defects using an infrared sensitive video camera. This method is useful for assessing the loss of posterior iris pigment in patients with the pigmentary dispersion syndrome and pigmentary glaucoma. Some patients with no transillumination defects on slit-lamp examination were noted to have discrete defects on infrared videography. This technique is a rapid, convenient, and reproducible method of permanently recording posterior iris pigment changes. These high-quality video images can then be followed to determine the natural course and the results of therapy in these patients.