title: Detection using the multifocal electroretinogram of mosaic retinal dysfunction in carriers of X-linked retinitis pigmentosa.
abstract: OBJECTIVE
  To examine whether a mosaic pattern of retinal dysfunction in obligate carriers of X-linked retinitis pigmentosa (XLRP) could be observed in local electroretinographic responses obtained with the multifocal electroretinogram (mfERG).
  
  
  METHODS
  Prospective observational case series.
  
  
  METHODS
  Five obligate carriers of XLRP (mean age, 53.2 years) were recruited into the study.
  
  
  METHODS
  Examination of each subject included a complete ocular examination, Humphrey visual field, standard full-field electroretinogram (ERG), and mfERG testing. For the mfERG, we used a 103-scaled hexagonal stimulus array that subtended a retinal area of approximately 40 in diameter. The amplitudes and implicit times in each location for the mfERG was compared with the corresponding value determined for a group of normally sighted, age-corrected control subjects.
  
  
  METHODS
  Mapping of 103 local electroretinographic response amplitudes and implicit times within the central 40 with the multifocal electroretinogram.
  
  
  RESULTS
  Localized regions of reduced mfERG amplitudes and/or delayed implicit times were found in four of five carriers. In one of these four carriers, a mosaic pattern of mfERG dysfunction was present even in the absence of any clinically apparent retinal changes, retinal sensitivity losses on Humphrey field testing, or abnormal full-field cone ERG responses. However, one carrier with a typical tapetal-like reflex demonstrated no deficit on any functional tests.
  
  
  CONCLUSIONS
  The mfERG demonstrated patchy areas of retinal dysfunction in some carriers of XLRP. This mosaic pattern of dysfunction may be observed in some patients with a normal-appearing fundus, normal psychophysical thresholds, and normal amplitude and implicit time full-field ERG cone responses.
authors.affiliation: Department of Ophthalmology and Visual Science, University of Illinois at Chicago, 1855 West Taylor Street, Chicago, IL 60612, USA.
authors.forename: Thasarat S
authors.initials: TS
authors.lastname: Vajaranant
authors.forename: William
authors.initials: W
authors.lastname: Seiple
authors.forename: Janet P
authors.initials: JP
authors.lastname: Szlyk
authors.forename: Gerald A
authors.initials: GA
authors.lastname: Fishman
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D004596:Electroretinography / Q000379:methods*; D008040:Genetic Linkage; D006579:Heterozygote; D006801:Humans; D008875:Middle Aged; D012160:Retina / Q000503:physiopathology*; D012174:Retinitis Pigmentosa / Q000235:genetics* / Q000503:physiopathology*; D014794:Visual Fields; D014960:X Chromosome