Subthreshold infrared footprinting with indocyanine green for localizing low-intensity infrared photocoagulation.

A novel technique for localizing subthreshold infrared (810 nm) laser treatment and its use in three patients is described. Two patients were treated for choroidal neovascularization with transpupillary thermotherapy or focal subthreshold photocoagulation, and the third patient was treated with grid laser photocoagulation for diabetic macular edema using the 810-nm laser after undergoing indocyanine green angiography for diagnostic purposes. Postoperative indocyanine green images, obtained without reinjection of indocyanine green, revealed areas of hypofluorescence that corresponded to the laser treatment spots. This technique, named subthreshold infrared footprinting, can precisely localize subthreshold infrared laser photocoagulation sites and is potentially useful for evaluating treatment postoperatively and planning additional therapy if necessary.