This document defines 10 common abbreviations used in ophthalmology and otolaryngology: 1. PE Tube - Pressure Equalizing Tube, a small tube placed in a child's eardrum to drain fluid and equalize pressure. 2. EENT - Eyes, ears, nose, and throat. An ENT specialist focuses on these areas while an otolaryngologist adds the head. 3. BC - Bone conduction, the conduction of sound through the bones of the skull.