A team of researchers from Minnesota found that the rate of spontaneous resolution of congenital nasolacrimal duct obstruction (CNLDO) plateaus after a child turns nine months old, and the success rate of initial probing declines after the child turns 15 months, suggesting that surgical intervention is necessary during this timeframe.

This retrospective study reviewed the medical records of 1,998 infants with CNLDO. Of the total cases, the researchers note that 1,669 (83.5%) spontaneously resolved, 289 (14.5%) underwent treatment and the remaining 40 (2.0%) were lost to follow-up. They add that of the 1,958 cases that followed up, 925 (47.3%) spontaneously resolved by the time the child turned three months, 1,300 (66.4%) by six months, 1,472 (75.7%) by nine months and 1,516 (78.4%) by 12 months.

The team found that the rate of resolution was 35% faster in children younger than one month compared with three months, 43% faster in children three months old compared with six months old, 39% faster in children six months old compared with nine months old and 1% slower in children nine months old compared with 12 months old.

They add that probing children at least 15 months old had decreased odds of resolution compared with probing children between 12 and 14 months old.