A technique of irrigation and bubble with saline and air through the upper lacrimal passages into the lacrimal sac is described for localizing and identifying the internal common punctum. The method requires no special equipment. It helps the surgeon avoid operative trauma to the punctum, and enables its placement in the center of the bony window during the dacryocystorhinostomy so that failure will be less likely to occur.
Hecht SD. Internal Common Punctum During DacryocystorhinostomyAccurate Localization by the Irrigation and Bubble Technique. Arch Ophthalmol. 1973;89(2):124. doi:10.1001/archopht.1973.01000040126015