title: Refractive state in children with unilateral congenital nasolacrimal duct obstruction.
abstract: OBJECTIVE
  To evaluate refractive state in children with unilateral congenital nasolacrimal duct obstruction (NLDO).
  
  
  METHODS
  This descriptive cross-sectional study includes consecutive children with unilateral congenital NLDO. Examination under anesthesia was performed to perform cycloplegic refraction and was followed by appropriate intervention in each patient. Refractive errors of the involved and sound fellow eyes were compared.
  
  
  RESULTS
  Ninety-four children with mean age of 25.4±20.4 months (range, 6 months to 10 years) were enrolled from May 2007 to January 2010. Based on spherical equivalent refractive error, hyperopia was more common in the affected eyes, however this difference failed to reach statistical significance (P=0.5). Anisometropia more and less than 0.5 diopters (D) was present in 25% and 43% of patients respectively. Interocular difference was significant in terms of spherical refractive error and spherical equivalent (P=0.003) but not cylindrical refractive error. When the comparison was limited to hyperopic eyes, the interocular difference became more significant in terms of spherical refractive error and spherical equivalent (P<0.001). Each month of increase in age was associated with an interocular difference of 0.007D in spherical refractive error (r=0.242, P=0.02). Older age at the time of intervention was associated with more procedures (r=0.297, P=0.004).
  
  
  CONCLUSIONS
  Unilateral congenital NLDO is associated with anisometropia especially anisohyperopia which may predispose affected children to amblyopia. With increasing age, the degree of anisometropia and the number of required procedures increase. It is prudent to perform refraction and initiate proper intervention at a younger age.
authors.affiliation: Ophthalmic Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors.forename: Abbas
authors.initials: A
authors.lastname: Bagheri
authors.forename: Sharareh
authors.initials: S
authors.lastname: Safapoor
authors.forename: Shahin
authors.initials: S
authors.lastname: Yazdani
authors.forename: Mehdi
authors.initials: M
authors.lastname: Yaseri
keywords: Amblyopia; Anisometropia; Nasolacrimal Duct Obstruction; Refraction