title: ON and OFF electroretinography and contrast sensitivity in Duchenne muscular dystrophy.
abstract: OBJECTIVE
  The study investigated possible asymmetric dysfunction of the ON and OFF visual mechanisms in DMD (Duchenne muscular dystrophy) patients associated with specific genetic alterations.
  
  
  METHODS
  nineteen DMD patients and 7 heterozygous dmd carriers were tested, as well as 19 age-matched controls.Full-field ergs were recorded using mesopic (1 cd/m(2)) and photopic (250 cd/m(2)) sawtooth luminance modulations as stimuli: rapid increase and ramping decrease (to isolate ON responses) or rapid decrease and ramping increase (for OFF responses). In addition, a psychophysical study comprised contrast sensitivity tests using two checkerboard stimuli at either higher (ON) or lower (OFF) luminance relative to the background: 0.3 cycles per degree (cpd) presented for 33 ms (low spatial frequency, short duration) and 2 cpd presented for 1500 ms (high spatial frequency, long duration).
  
  
  RESULTS
  A significant ERG amplitude reduction, relative to controls, was detected in the DMD patients in the mesopic positive peaks for both ON and OFF stimuli, as well as for the photopic ON stimulus (P < 0.05). Contrast sensitivity was significantly lower in the DMD patients (P < 0.05) relative to controls for the ON stimuli. Neither the ERG nor the contrast sensitivities were altered in the carriers.
  
  
  CONCLUSIONS
  This study suggests that there are ON and OFF ERG alterations when both rods and cones contribute to the ERG responses in DMD patients. When only cones are activated there is an asymmetrical ERG alteration, also revealed by the contrast sensitivity measurements.
authors.affiliation: Núcleo de Neurociências e Comportamento, Universidade de São Paulo, São Paulo, Brazil. mirellabarboni@usp.br
authors.forename: Mirella Telles Salgueiro
authors.initials: MT
authors.lastname: Barboni
authors.forename: Balázs Vince
authors.initials: BV
authors.lastname: Nagy
authors.forename: Ana Laura
authors.initials: AL
authors.lastname: de Araújo Moura
authors.forename: Francisco Max
authors.initials: FM
authors.lastname: Damico
authors.forename: Marcelo Fernandes
authors.initials: MF
authors.lastname: da Costa
authors.forename: Jan
authors.initials: J
authors.lastname: Kremers
authors.forename: Dora Fix
authors.initials: DF
authors.lastname: Ventura
mesh_terms: D000293:Adolescent; D000328:Adult; D055253:Color Vision / Q000502:physiology; D015350:Contrast Sensitivity / Q000502:physiology*; D016189:Dystrophin / Q000235:genetics; D004596:Electroretinography; D005260:Female; D006801:Humans; D008297:Male; D055255:Mesopic Vision / Q000502:physiology; D020388:Muscular Dystrophy, Duchenne / Q000235:genetics / Q000503:physiopathology*; D010775:Photic Stimulation; D020419:Photoreceptor Cells, Vertebrate / Q000502:physiology*
chemical_list: D016189:Dystrophin
keywords: ON OFF pathways; contrast sensitivity; dystrophin; electroretinogram; retina