title: Cone and rod dysfunction in fundus albipunctatus with RDH5 mutation: an electrophysiological study.
abstract: OBJECTIVE
  A prior study showed that some patients with fundus albipunctatus (FA) have severely reduced full-field cone ERGs. The purpose of this study was to investigate the frequency of cone dysfunction and to determine the cause of the reduced full-field cone ERGs in patients with FA and whether the rod system is affected in patients with FA.
  
  
  METHODS
  Sixteen consecutive patients with FA (from 1993 to 2003; eight males, eight females; mean age, 25.4 years) with an RDH5 gene mutation were studied. The amplitudes and implicit times of the standard cone ERGs in the patients with FA were compared to those obtained from normal subjects (n = 55). The a-waves of cone ERGs were also elicited by a bright flash and were fitted to a mathematical model of the a-wave. Rod ERG responses were elicited by dim blue flashes after 3 hours of dark adaptation.
  
  
  RESULTS
  The amplitude of the b-wave of the cone ERG in the FA group varied considerably from within the normal limits to markedly decreased. Six of 16 patients with FA had b-wave amplitudes that were smaller than the lowest limit of the control subjects. The degree of cone dysfunction tended to be more severe in older patients. The analysis of the cone a-wave demonstrated that R(m) (maximal response amplitude) in the patients with FA with reduced standard cone ERGs was significantly smaller than that in control subjects. Rod ERGs were also reduced in the patients with FA who had reduced cone ERGs.
  
  
  CONCLUSIONS
  In patients with FA, 38% had extensive cone dysfunction. The reduced full-field cone ERGs were mainly due to the loss of cone photoreceptors, and the rod system was also affected in some patients.
authors.affiliation: Department of Ophthalmology, Nagoya University School of Medicine, Nagoya, Japan.
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Niwa
authors.forename: Mineo
authors.initials: M
authors.lastname: Kondo
authors.forename: Shinji
authors.initials: S
authors.lastname: Ueno
authors.forename: Makoto
authors.initials: M
authors.lastname: Nakamura
authors.forename: Hiroko
authors.initials: H
authors.lastname: Terasaki
authors.forename: Yozo
authors.initials: Y
authors.lastname: Miyake
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000429:Alcohol Oxidoreductases / Q000235:genetics*; D002648:Child; D003623:Dark Adaptation; D004596:Electroretinography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009154:Mutation; D009755:Night Blindness / Q000235:genetics* / Q000503:physiopathology*; D010775:Photic Stimulation; D010857:Pigment Epithelium of Eye / Q000473:pathology; D017949:Retinal Cone Photoreceptor Cells / Q000503:physiopathology*; D017948:Retinal Rod Photoreceptor Cells / Q000503:physiopathology*
chemical_list: D000429:Alcohol Oxidoreductases; C105846:retinol dehydrogenase 5