title: Visual impairment in Finnish Usher syndrome type III.
abstract: OBJECTIVE
  To evaluate visual impairment in Finnish Usher syndrome type 3 (USH3) and compare this with visual impairment in Usher syndrome types 1b (USH1b) and 2a (USH2a).
  
  
  METHODS
  We carried out a retrospective study of 28 Finnish USH3 patients, 24 Dutch USH2a patients and 17 Dutch USH1b patients. Cross-sectional regression analyses of the functional acuity score (FAS), functional field score (FFS*) and functional vision score (FVS*) related to age were performed for all patients. The FFS* and FVS* were calculated using the isoptre V-4 test target instead of the usual III-4 target. Statistical tests relating to regression lines and Student's t-test were used to compare between USH3 patients and the other genetic subtypes of Usher syndrome.
  
  
  RESULTS
  Cross-sectional analyses revealed significant deterioration in the FAS (1.3% per year), FFS* (1.4% per year) and FVS* (1.8% per year) with advancing age in the USH3 patient group. At a given age the USH3 patients showed significantly poorer visual field function than the USH2a patients.
  
  
  CONCLUSIONS
  The rate of deterioration in visual function in Finnish USH3 patients was fairly similar to that in Dutch USH1b or USH2a patients. At a given age, visual field impairment in USH3 patients was similar to that in USH1b patients but poorer than in USH2a patients.
authors.affiliation: Department of Ophthalmology, Radboud University Nijmegen Medical Centre, Nijmegen, the Netherlands.
authors.forename: Rutger F
authors.initials: RF
authors.lastname: Plantinga
authors.forename: Ronald J E
authors.initials: RJ
authors.lastname: Pennings
authors.forename: Patrick L M
authors.initials: PL
authors.lastname: Huygen
authors.forename: Eeva-Marja
authors.initials: EM
authors.lastname: Sankila
authors.forename: Kaija
authors.initials: K
authors.lastname: Tuppurainen
authors.forename: Leenamaija
authors.initials: L
authors.lastname: Kleemola
authors.forename: Cor W R J
authors.initials: CW
authors.lastname: Cremers
authors.forename: August F
authors.initials: AF
authors.lastname: Deutman
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D003430:Cross-Sectional Studies; D005387:Finland; D005838:Genotype; D006801:Humans; D008875:Middle Aged; D010641:Phenotype; D012189:Retrospective Studies; D052245:Usher Syndromes / Q000235:genetics / Q000503:physiopathology*; D014786:Vision Disorders / Q000503:physiopathology*; D014792:Visual Acuity / Q000502:physiology*; D058609:Visual Field Tests; D014794:Visual Fields / Q000502:physiology*