Abstract
Purpose: :
To evaluate the retinal function in children with genetically different forms of Usher syndrome, with emphasis on phenotype and rate of progression of the retinal degeneration.
Methods: :
14 children (average 5.9 years old) with retinitis pigmentosa and hearing impairment were examined with full-field electroretinography (ERG), during general anaesthesia, for evaluation of the retinal dysfunction. In addition to ophthalmological examination, they were all investigated regarding mutations in known genes for Usher syndrome. 5 of the children were further examined with repeated full-field ERG in local anaesthesia during a period of 5 - 10 years. These results were compared to full-field ERG data from 58 children without retinal eye disorder, examined during the same conditions. The central retinal function was evaluated with multifocal ERG and optical coherence tomography (OCT) in 2 of the children at follow up.
Results: :
The three different forms of Usher (type 1, 2 and 3) were identified among these children. Full-field ERG demonstrated early alterations in both cone and rod function, but a remaining rod function could be verified in the majority of the children under the age of 4 years. In all children the cone function was moderately reduced, compared to full-field ERG from the 58 children without any eye disorder. Multifocal ERG confirmed a preserved central cone function in early teens, further confirmed with only discrete structural alterations in OCT.
Conclusions: :
Retinal function in children with Usher syndrome demonstrates variable phenotypes and different degrees in rate of progression during childhood. Full-field ERG during general anaesthesia in combination with DNA screening of known mutations are two reliable and crucial methods for achieving an early diagnosis of Usher syndrome in children and infants.
Keywords: retinal degenerations: hereditary • electrophysiology: clinical