Longitudinal study of spherical refractive error in infantile nystagmus syndrome.
OBJECTIVE
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 Infantile nystagmus syndrome (INS) [n = 22 (albinism n = 18, idiopathic infantile nystagmus n = 4)] (aged 0-4) were also recruited. Cycloplegic streak retinoscopy was performed biannually, over a 3 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 < 0.05). Individual data demonstrated relatively static spherical equivalent refractive errors over time. Prospective participants were hypermetropic at all visits and those with albinism had, on average, higher refractive errors than those with idiopathic infantile nystagmus (IIN). No significant correlations were noted between visual acuity and spherical equivalent refractive errors or most ametropic meridian.


CONCLUSIONS
Hypermetropia is the most prevalent spherical refractive error in the INS population, irrespective of level of visual acuity. Individuals with infantile nystagmus syndrome fail to demonstrate typical patterns of emmetropisation, particularly in the presence of albinism.
University of Ulster, Coleraine, UK; The Royal Group of Hospitals, Belfast, UK; Altnagelvin Area Hospital, Altnagelvin, UK.
Natasha
N
Healey
Julie F
JF
McClelland
Kathryn J
KJ
Saunders
A Jonathan
AJ
Jackson
D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D008137:Longitudinal Studies; D008297:Male; D009660:Northern Ireland / Q000453:epidemiology; D020417:Nystagmus, Congenital / Q000150:complications*; D015995:Prevalence; D012030:Refractive Errors / Q000453:epidemiology*; D012189:Retrospective Studies
albinism; emmetropisation; infantile nystagmus syndrome; nystagmus; refractive error