Management of strabismus associated with infantile nystagmus syndrome: A novel classification to assist in surgical planning

Purpose There is no consensus on surgical management of head position associated with infantile nystagmus syndrome (INS) when strabismus coexists, and very little outcomes data have been published. We propose classifying strabismus into concordant or discordant based on the relationship between head positioning and strabismus, and modifying surgery accordingly. Our objective is to describe this system and to review surgical outcomes. Design Retrospective observational case series Methods 28 INS patients with coexisting horizontal strabismus underwent surgery for horizontal head positioning had ≥2 months follow-up from 1995-2018 at Vanderbilt Eye Institute. Outcome variables included head positioning (minimal: ≤10°, Mild: 11-30°, Moderate: 31-44°, Severe: ≥45°), strabismus (Range: 0-70 prism diopters (PD), minimal: ≤10PD), and reoperation rates. Nonparametric Wilcoxon Signed-rank, Fischer Exact, and Mann Whitney U tests were used for statistical analysis. Results 21 cases were concordant, and 7 were discordant; the mean follow-up was 4.1 years. Head positioning: 96% had moderate to severe head positioning at baseline. Correction rates (to minimal) were 100% at 2-5 months postoperatively and 86% at last follow-up (p Conclusions Our classification system in patients with INS allows a systematic way to surgically improve head positioning and strabismus in cases of moderate to severe baseline head positioning