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Subnormal visual acuity (SVAS) and albinism in Mexican 12-13-year-old children.

Författare och institution:
Anders Sjöström (Institutionen för klinisk neurovetenskap, Sektionen för oftalmologi); Maria Kraemer (Institutionen för klinisk neurovetenskap, Sektionen för oftalmologi); Josefin Ohlsson (Institutionen för klinisk neurovetenskap, Sektionen för oftalmologi); Graciella Garay-Cerro (-); Maths Abrahamsson (Institutionen för klinisk neurovetenskap, Sektionen för oftalmologi); Gerardo Villarreal (Institutionen för klinisk neurovetenskap)
Publicerad i:
Documenta ophthalmologica. Advances in ophthalmology, 108 ( 1 ) s. 9-15
Artikel, refereegranskad vetenskaplig
Sammanfattning (abstract):
BACKGROUND: In a previous study the vision of 1046 12-13-year-olds in Sweden was examined. Of those 67 had some kind of visual disturbances and in 20 no obvious cause was found. In this group, defined as children with subnormal visual acuity syndromes (SVAS), albinism was shown to be a major cause to the visual dysfunction giving a prevalence of about 1%. This is about 100 times higher than previous figures. Albinism can therefore be the cause in many cases of unexplained low visual acuity, at least in Sweden. Subnormal visual acuity is usually found in 2-4% in a pediatric population and is often called 'amblyopia'. The Swedish study showed that in many cases 'amblyopia' should be replaced by 'SVAS' and further investigation. The present Mexican study was designed identically to the Swedish study. The objective was to describe the distribution of visual acuity and the prevalence of ocular disorders, including incidence of subnormal visual acuity (SVAS) and the occurrence of albinism in a Mexican population of 12-13-year-olds. SUBJECTS AND METHODS: Altogether 1035 children, 12-13 years of age, were examined. A total number of 344 children were referred to the university pediatric eye clinic for further examination. 272 of these had simple refractive errors, 59 were diagnosed with an ophthalmological disorder and 13 children could not be pathologically classified. These were referred to a second ophthalmological examination, including VEP (Visual Evoked Potential) recordings. VEP reveals an asymmetric (right vs. left) cortical response after monocular stimulation in albinism. RESULTS: No child showed iris translucency or any other typical albinoic sign. VEP was recorded from 11 children. Three children showed an asymmetric VEP and were classified as albinos. The VEP response was normal in 8 of the children. CONCLUSIONS: The results indicate that albinism is common in Mexico, although not as common as in a similar Swedish population. A prevalence of albinism of approximately 0.3% was found in the Mexican population, compared to approximately 1% in the Swedish study group. The number of albinos was much higher in both study groups than to be expected from previous estimates. The difference between the Swedish and the Mexican figures may be explained by the general difference in pigmentation between Sweden and Mexico and thus probably by the subsequent lower number of commonly occurring albino foci in the Mexican heritage. It is emphasised that in investigations of children with SVAS, also in countries with a generally high pigmentation level, electro-physiological examinations are important, to be able to reveal albinism, but also to exclude or verify other conditions in the SVAS group, for example neurometabolic conditions.
Ämne (baseras på Högskoleverkets indelning av forskningsämnen):
Klinisk medicin ->
Adolescent, Albinism, Ocular, diagnosis, epidemiology, Child, Evoked Potentials, Visual, Humans, Mexico, epidemiology, Prevalence, Vision Disorders, diagnosis, epidemiology, Visual Acuity
Postens nummer:
Posten skapad:
2007-11-21 16:11
Posten ändrad:
2011-01-20 09:58

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