title: Factors related to strabismus decompensation after a period of prolonged postoperative stability.
abstract: OBJECTIVE
  To identify factors associated with late decompensation of horizontal strabismus after a period of prolonged (>12 months) postoperative stability.
  
  
  METHODS
  Charts from all pediatric horizontal strabismus surgical cases from 1999 to 2009 were reviewed. Patients with a distance or near alignment of <10(Δ) at the first visit >12 months following surgery were included. The primary outcome was time from surgery to strabismus decompensation. Multiple variables were analyzed using the Cox proportional hazards model.
  
  
  RESULTS
  A total of 185 cases were included. Mean age at surgery was 5.1 years and mean follow-up was 62.2 months. Late decompensation rate was 31%; of these, 54% underwent reoperation. Using two different models, a higher risk of decompensation was associated with both the presence of preoperative oblique dysfunction (P = 0.023/0.002) and larger distance/near deviations at the first >12 months postoperative visit (P = 0.033/0.012).
  
  
  CONCLUSIONS
  Worsening of alignment >12 months after horizontal strabismus surgery occurs in almost one-third of patients. Preoperative oblique dysfunction is associated with long-term instability, possibly because it is a surrogate for sensory torsion and poor fusion. Additionally, larger distance and near deviations at >12 months after surgery were each associated with late decompensation. The rate of decompensation for patients with deviations of 0(Δ) to <4(Δ) was less than those with deviations of 4(Δ) to <8(Δ) and >8(Δ), suggesting that the biologic behavior of all deviations within the monofixation range (0(Δ) to 8(Δ)) is not uniform.
authors.affiliation: Department of Ophthalmology, University of Oklahoma/Dean McGee Eye Institute, Oklahoma City, Oklahoma.
authors.forename: Eldad
authors.initials: E
authors.lastname: Adler
authors.affiliation: Department of Biostatistics and Epidemiology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma.
authors.forename: Kai
authors.initials: K
authors.lastname: Ding
authors.affiliation: Department of Ophthalmology, University of Oklahoma/Dean McGee Eye Institute, Oklahoma City, Oklahoma. Electronic address: rmichael-siatkowski@dmei.org.
authors.forename: R Michael
authors.initials: RM
authors.lastname: Siatkowski
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007223:Infant; D008297:Male; D009801:Oculomotor Muscles / Q000473:pathology / Q000601:surgery*; D013508:Ophthalmologic Surgical Procedures; D011183:Postoperative Complications; D016016:Proportional Hazards Models; D012008:Recurrence; D012307:Risk Factors; D013285:Strabismus / Q000209:etiology* / Q000601:surgery*; D013997:Time Factors