DCR is indicated in the treatment of tearing due to nasolacrimal duct obstruction. Blockage of this duct can be due to trauma, prior surgery, tumor, or inflammatory medical conditions, but most commonly occurs without an identifiable cause. To determine if this is truly the problem area in a patient with tearing, a number of tests may be performed. A physical examination is performed by the physician, and is often followed by probing and irrigation of the canalicular system (Figure 2). Placement of dye in the tears may be observed and timed for clearance. This evaluation is easily done and well-tolerated in the office setting.