results of nasolacrimal duct probing in children between 9-48 months.

congenital nasolacrimal duct obstruction (cnldo) is a common disease in children. the classic treatment of cnldo is probing that was done around one year old. however, controversy exists regarding the outcome of probing in children older than one year. this study aimed to find the cure rate of initial probing for cnldo and identify factors producing the failure rate in old age. in this retrospective interventional case series study, 100 eyes of 92 patients aged 9-48 months with cnldo underwent probing with general anesthesia. according to the intraoperative results of probing, cnldo were categorized in two groups of membranous obstruction at the end of nasolacrimal duct obstruction (nld) and complex obstruction at canaliculus, lacrimal sac and n ld. patients were categorized in three groups according to the age of probing into under 12, 12 to 24 and over 24 months. success rate was defined as successful irrigation of nld intraoperatively and absence of lacrimation and discharge at 1 week, one, three and six months postoperatively. the average age of patients and probing were 47.35±25.59 and 17.32±7.85 months respectively. membranous obstruction accounted for 72% of patients and remainder had complex type. an overall cure rate of 91%, 89% and 60% was found in patients aged 9-12, 12-24 and 24-48 months respectively. surgery success rate after six months was 91% in membranous group and 52% in complex group. there was a significant relation between the type of obstruction and opening of nld (p<0.o01). this study showed that the probing failure of probing after one year was related to the complexity of obstruction rather than the age of the patient. it is recommended that probing could safely be done in under 4 years old.