title: Rod and cone a-waves in three cases of Bietti crystalline chorioretinal dystrophy.
abstract: OBJECTIVE
  To estimate retinal function in Bietti crystalline chorioretinal dystrophy using the electroretinogram.
  
  
  METHODS
  In this observational case series, the scotopic and photopic electroretinograms in three Japanese female patients (case 1, 55 years old; case 2, 56 years old; case 3, 47 years old) who showed bilateral crystalline retinal deposits but no corneal deposits were recorded. The rod and cone a-waves were analyzed by using the method described by Hood and Birch (1995, 1997). The parameters Rm(p3) (maximum a-wave amplitude) and S (sensitivity) were calculated.
  
  
  RESULTS
  In case 1, the rod Rm(p3) was decreased in both eyes. The rod S in the right eye was within the normal range, but that in the left eye was significantly reduced. Although the cone Rm(p3) was decreased, the cone S was within the normal range. In case 2, the rod and cone Rm(p3) was reduced, but the rod and cone S was within the normal range in both eyes. In case 3, the rod and cone Rm(p3) and S were within the normal range.
  
  
  CONCLUSIONS
  Electroretinograms illustrated different disease stages, however, no eye with normal Rm(p3) and decreased S was found in rods and cones. In the early stages of this disease, decreased numbers of photoreceptors and/or outer segment shortening may be present while phototransduction remains normal. As the damage to the retina progresses, phototransduction becomes severely affected. Because reduced cone S was not observed in our cases, cones may be less involved than rods in this disease.
authors.affiliation: Department of Ophthalmology, Niigata University School of Medicine, 1-757 Asahimachi, Niigata 951-8510, Japan. usuit@med.niigata-u.ac.jp
authors.forename: T
authors.initials: T
authors.lastname: Usui
authors.forename: N
authors.initials: N
authors.lastname: Tanimoto
authors.forename: M
authors.initials: M
authors.lastname: Takagi
authors.forename: S
authors.initials: S
authors.lastname: Hasegawa
authors.forename: H
authors.initials: H
authors.lastname: Abe
mesh_terms: D003460:Crystallization; D003623:Dark Adaptation; D004596:Electroretinography; D005260:Female; D005654:Fundus Oculi; D006801:Humans; D008875:Middle Aged; D010775:Photic Stimulation; D017949:Retinal Cone Photoreceptor Cells / Q000503:physiopathology*; D012162:Retinal Degeneration / Q000503:physiopathology*; D017948:Retinal Rod Photoreceptor Cells / Q000503:physiopathology*; D014785:Vision, Ocular; D014792:Visual Acuity