BACKGROUND. The infraorbital recess of the maxillary sinus can reach in front of the nasolacrimal duct to become prelacrimal recess. During a routine Cone Beam CT (CBCT) study of a male patient of 72 years old, there were bilaterally found infraorbital maxillary air cells (IMACs) resulted after the almost complete closure of infraorbital recesses of the maxillary sinuses. Only that on the left side was reaching in front of the nasolacrimal canal. The closure of each infraorbital recess leaded to a narrow draining passage opened in the terminal end of the maxillary infundibulum, thus proximal to the maxillary sinus ostium. On the left side, a small cell of the lacrimal bone was interposed between the IMAC drainage pathway and the nasolacrimal canal. On the right side, the nasolacrimal canal was communicating with the ethmoidal infundibulum. Such an anatomic variation in the infraorbital angle of the maxillary sinus can impede the endoscopic procedures which use the anterior lacrimal pathway.
