eye disorders
Dacryostenosis
Introduction
Dacryostenosis is obstruction or stenosis of the nasolacrimal duct, causing excess tearing. Nasolacrimal obstruction may be congenital or acquired. One cause of congenital obstruction is inadequate development of any part of the nasolacrimal ducts. Typically, a membrane at the distal end of the nasolacrimal duct persists (valve of Hasner). There is tearing and purulent discharge; the condition may manifest as chronic conjunctivitis, usually beginning after the age of 2 weeks (most often at age 3 to 12 weeks). There are many causes of acquired nasolacrimal duct obstruction. The cause is most often age-related stenosis of the nasolacrimal duct. Other causes include past nasal or facial bone fractures and sinus surgery, which disrupt the nasolacrimal duct; inflammatory diseases (eg, Sarcoidosis , Causes of punctal or canalicular stenosis include chronic conjunctivitis (especially herpes simplex), certain types of chemotherapy, adverse reactions to eye drops (especially topicalechothiophateiodide), and radiation. 