We studied spontaneous resolution of congenital nasolacrimal duct obst
ruction in the second year of life and compared this with the cure rat
e after probings undertaken between the ages of 11 and 15 months, Of t
he 111 eyes of 95 patients studied, 26 eyes were included in a randomi
sed prospective comparison of probing with spontaneous resolution, A f
urther 63 eyes followed a similar management plan to the randomised gr
oup 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 resoluti
on (p = 0.04). At 24 months of age probing was superior in both random
ised and non-randomised studies, but with increased numbers in the spo
ntaneous resolution groups the difference was no longer statistically
significant, Up to 18 months of age the frequency of spontaneous resol
ution makes delay in probing a viable management option to be discusse
d with the parents, It will also lead to an overestimate of the cure r
ate in any study of interventional treatment unless controls are inclu
ded.