Changes in Astigmatism in Children With Congenital Nasolacrimal Duct Obstruction Undergoing Probing and Irrigation

Background Congenital nasolacrimal duct obstruction (CNLDO) is a frequent condition during infancy. While it is often self-limited, persistent cases may require probing and irrigation (P&I). Because this disorder affects the critical period of visual development, concerns have been raised about its potential role in amblyopia through induced refractive changes, particularly astigmatism. Methods A Retrospective, single-center cohort study. Medical records of children with CNLDO treated at Sheba Medical Center (2009–2024) were reviewed. Inclusion required P&I and paired cycloplegic refractions before surgery and 6–36 months postoperatively. Pre- and postoperative spherical equivalent (SE) and cylinder were compared using paired t-tests, stratified by age at last procedure (< 24 vs ≥ 24 months). Proportions with any measurable cylinder were tested with McNemar’s test. Results Of the 401 children screened, 25 met the inclusion criteria. Fourteen were treated before 24 months of age, and 11 at or after 24 months. SE showed a nonsignificant myopic shift (Δ = -0.43D, p = 0.065). In contrast, cylinder values increased from − 0.39 ± 0.70D to -0.87 ± 0.98D (p = 0.040). The proportion of measurable cylinder rose from 32% to 68% (p = 0.012). Later treated children had a greater mean increase (to -1.20 ± 1.14D), and among those with baseline cylinder, the mean reached − 1.47D, which is a borderline amblyogenic value. Conclusion CNLDO is associated with increased cylinder and astigmatism, with children treated later in life showing an even higher risk of progression toward amblyogenic levels. These findings support structured postoperative refractive follow-up and early surgical intervention whenever possible.