title: Photoreceptor and postreceptor responses in congenital stationary night blindness.
abstract: OBJECTIVE
  To investigate photoreceptor and postreceptor retinal function in patients with congenital stationary night blindness (CSNB).
  
  
  METHODS
  Forty-one patients with CSNB (ages 0.19-32 years) were studied. ERG responses to a series of full-field stimuli were obtained under scotopic and photopic conditions and were used to categorize the CSNB patients as complete (cCSNB) or incomplete (iCSNB). Rod and cone photoreceptor (R(ROD), S(ROD), R(CONE), S(CONE)) and rod-driven postreceptor (V(MAX), log σ) response parameters were calculated from the a- and b-waves. Cone-driven responses to 30 Hz flicker and ON and OFF responses to a long duration (150 ms) flash were also obtained. Dark-adapted thresholds were measured. Analysis of variance was used to compare data from patients with cCSNB, patients with iCSNB, and controls.
  
  
  RESULTS
  We found significant reduction in saturated photoreceptor amplitude (R(ROD), R(CONE)) but normal photoreceptor sensitivity (S(ROD), S(CONE)) in both CSNB groups. Rod-driven postreceptor response amplitude (V(MAX)) and sensitivity (log σ) were significantly reduced in CSNB. Log σ was significantly worse in cCSNB than in iCSNB; this was the only scotopic parameter that differed between the two CSNB groups. Photopic b-wave amplitude increased monotonically with stimulus strength in CSNB patients rather than showing a normal photopic hill. The amplitude of the 30-Hz flicker response was reduced compared with controls, more so in iCSNB than in cCSNB. The mean dark-adapted threshold was significantly elevated in CSNB, more so in cCSNB than in iCSNB.
  
  
  CONCLUSIONS
  These results are evidence of normal photoreceptor function (despite the low saturated photoresponse amplitude) and anomalous postreceptor retinal circuitry.
authors.affiliation: Department of Ophthalmology, Boston Children's Hospital, Boston, Massachusetts 02215, USA. Aparna.Raghuram@childrens.harvard.edu
authors.forename: Aparna
authors.initials: A
authors.lastname: Raghuram
authors.forename: Ronald M
authors.initials: RM
authors.lastname: Hansen
authors.forename: Anne
authors.initials: A
authors.lastname: Moskowitz
authors.forename: Anne B
authors.initials: AB
authors.lastname: Fulton
mesh_terms: D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D002648:Child; D002675:Child, Preschool; D003623:Dark Adaptation / Q000502:physiology*; D004596:Electroretinography; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D009755:Night Blindness / Q000151:congenital / Q000503:physiopathology*; D017949:Retinal Cone Photoreceptor Cells / Q000502:physiology*; D017948:Retinal Rod Photoreceptor Cells / Q000502:physiology*; D012684:Sensory Thresholds / Q000502:physiology; D055815:Young Adult
keywords: congenital stationary night blindness; dark-adapted threshold; electroretinogram; photoreceptor; postreceptor