Alteration of rod and cone function in children with Usher syndrome

Purpose. To evaluate the retinal function, with emphasis on phenotype and rate of progression, in infants and children with different genotypes of Usher syndrome. Methods. Fourteen children (2-10 years of age) with retinitis pigmentosaand hearing impairment were examined with full-field electroretinography( ERG) during general anesthesia, ophthalmologic examination, and genetic analysis. Five children were repeatedly examined (follow-up 5-10 years) with full-field ERGunder local anesthesia and in 2 children multifocal ERGand optical coherence tomography (OCT) were performed. These results were compared to full-field ERGdata from 58 children without retinal eye disorder. Results. Six children were genotyped as Usher 1B, 2A, and 3A. Full-field ERGdemonstrated early alterations corresponding to a rod- cone dystrophyin all children. A remaining rod function could be verified in the majority of the children up to 4 years of age. After 4 years of age, there was a further deterioration of the rod function; the progress was severe in Usher types 1 and 2 and moderate in Usher type 3. In all children, the cone function was moderately reduced, in a few cases almost normal. The results from the 58 children without retinal disorder confirm that full-field ERGduring general anesthesia is reliable. Multifocal ERGconfirmed a preserved central cone function and in OCT there were discrete structural alterations. Conclusions. Full-field ERGduring general anesthesia in children with Usher syndromedemonstrates variable phenotypes and different degrees in rate of progression during childhood. (Less)