title: Axial length estimation in strabismic patients.
abstract: BACKGROUND
  Previous studies have indicated that axial length determination is important in strabismic patients for defining the limit for a safe maximum recession of the medial rectus. Also, the response to strabismus surgery may be, in part, a function of axial length. We previously published a formula for predicting axial length based on age and refractive error; however, its accuracy has not been tested in a patient population that is different from the one used to generate the formula. The purpose of this study is to test a formula for estimating axial length, given age and refractive error, in a population that is different from that from which it was generated.
  
  
  METHODS
  We measured axial length using A-scan ultrasonography in 163 consecutive patients undergoing strabismus surgery. Twenty-nine patients were younger than 18 months of age; 134 patients were between 18 months and 10 years of age. We compared the measured axial length determination with the axial length value estimated by a formula generated from our previous published series.
  
  
  RESULTS
  For patients younger than 18 months of age, the equation estimated axial length within 0.5 mm in 41.4% of patients, within 1.0 mm in 79.3% of patients, and within 1.5 mm in 93.1% of patients. For patients between 18 months and 18 years of age, the formula estimated axial length within 0.5 mm in 37.3% of patients, within 1.0 mm in 73.1% of patients, and within 1.5 mm in 87.3% of patients.
  
  
  CONCLUSIONS
  The formula may be useful for the strabismus surgeon in estimating axial length when A-scan ultrasonography is not available in an operating room setting, particularly in congenital esotropes who require larger recessions in small eyes. If, however, A-scan ultrasonography is available, it is preferable to using the formula. The formula is not sufficiently accurate for use for calculating intraocular lens power.
authors.affiliation: Department of Ophthalmology & Visual Sciences, University of Wisconsin, Madison, USA.
authors.forename: B J
authors.initials: BJ
authors.lastname: Kushner
authors.forename: C O
authors.initials: CO
authors.lastname: Qui
authors.forename: N J
authors.initials: NJ
authors.lastname: Lucchese
authors.forename: M R
authors.initials: MR
authors.lastname: Fisher
mesh_terms: D002648:Child; D002675:Child, Preschool; D005123:Eye / Q000000981:diagnostic imaging / Q000473:pathology*; D006801:Humans; D007223:Infant; D012030:Refractive Errors / Q000473:pathology; D013285:Strabismus / Q000000981:diagnostic imaging / Q000473:pathology* / Q000601:surgery; D014463:Ultrasonography