Congenital nasolacrimal duct obstruction in the second year of life: a multicentre trial of management. 
We studied spontaneous resolution of congenital nasolacrimal duct obstruction in the second year of life and compared this with the cure rate after probings undertaken between the ages of 11 and 15 months.  Of the 111 eyes of 95 patients studied, 26 eyes were included in a randomised prospective comparison of probing with spontaneous resolution.  A further 63 eyes followed a similar management plan to the randomised group and are reported as an observational study.  Thirty of the 50 eyes followed up without treatment resolved spontaneously before the age of 2 years, of which 24 resolved before 18 months.  The overall cure rate for probing was 74% compared with 60% for spontaneous resolution.  At 15 months of age the randomised study confirmed that probing at 12-14 months is an effective intervention compared with spontaneous resolution (p = 0.04).  At 24 months of age probing was superior in both randomised and non-randomised studies, but with increased numbers in the spontaneous resolution groups the difference was no longer statistically significant.  Up to 18 months of age the frequency of spontaneous resolution makes delay in probing a viable management option to be discussed with the parents.  It will also lead to an overestimate of the cure rate in any study of interventional treatment unless controls are included.