The frequency of entry into an ethmoidal sinus when performing a dacryocystorhinostomy.

Ethmoidal sinuses intervening between the lacrimal sac and the nose can cause confusion when performing a dacryocystorhinostomy (DCR). This study aimed to assess the frequency of entry into ethmoidal sinuses when performing a DCR and to identify any helpful distinguishing features, at surgery, between the ethmoidal and nasal spaces. Ethmoidal sinuses were initially entered in 23 of 50 standard DCRs (46%) in which the ostium was performed via the standard lacrimal fissure. Nasal mucosa was found to be 2 to 3 times thicker than ethmoidal sinus mucosa and less friable. Being aware of the risk of entering an ethmoidal sinus and of the anatomical differences between ethmoidal and nasal tissue greatly aids location during surgery and allows edge-to-edge suturing of sac mucosa to nasal mucosa in all cases.