Longitudinal study of spherical refractive error in infantilenystagmus syndrome

Purpose: To explore the onset and progression of spherical refractive error in a population with infantile nystagmus syndrome.Methods: Retrospective refractive error data were obtained from 147 medical records of children with infantile nystagmus syndrome (albinism n=98; idiopathic infantile nystagmus n=49), attending a low vision clinic in Northern Ireland, over a 24 year period (1986-2010). Data were categorised by age to allow for comparisons with published studies. A prospective group of participants with INS (n=22 [albinism n=18, idiopathic infantile nystagmus n=4]) (aged 0-4 years) were also recruited. Cycloplegic streak retinoscopy was performed biannually, over a three year period. Spherical equivalent refractive error and most ametropic meridian were analysed.Results: The mean spherical equivalent refractive errors for albinism and idiopathic infantile nystagmus groups (across all age categories) were hypermetropic, with highest levels demonstrated by the participants with albinism aged 1≤4 years (Mann-Whitney U test, p=0.013). Mean most ametropic meridian was highest in the albinism group aged 1≤12 years (Mann-Whitney U test, p