title: Long-term decline of central cone function in retinitis pigmentosa evaluated by focal electroretinogram.
abstract: OBJECTIVE
  We evaluated long-term changes of central cone-mediated function in retinitis pigmentosa (RP) patients by recording focal electroretinograms (fERG).
  
  
  METHODS
  A cohort of 43 RP patients was followed from 4 to 16 years (average follow-up 9.3 years, average 10 examinations/patient) by recording the fERG response to a flickering uniform red field overlaying the central 18° of visual field (VF). Statistical censoring led to a reduced dataset of 32 patients (autosomal dominant 9, recessive 5, sporadic 5, x-linked 1, Usher II 12), from which long-term decay rates were estimated by global fitting of individual fERG amplitude time-curves.
  
  
  RESULTS
  Long-term follow-up of central cone FERG amplitude showed two main features: short-term variability and long-term decline. fERG short-term variability range was 0.14 to 0.2 log units. Mean yearly decay rate of central fERG was 5.6% (95% confidence interval [CI] 4%-7%). Yearly decline depended on inheritance pattern, being significantly greater in autosomal recessive and sporadic compared to autosomal dominant RP. The degree of central cone fERG decline was unrelated to the size of the residual VF.
  
  
  CONCLUSIONS
  The decline of central cone function is significantly slower than global cone function decline in RP. Central cone fERG loss is independent of residual VF.
authors.affiliation: Institute of Ophthalmology, Policlinico Gemelli, Catholic University, Rome, Italy. bfalsini@rm.unicatt.it
authors.forename: Benedetto
authors.initials: B
authors.lastname: Falsini
authors.forename: Lucia
authors.initials: L
authors.lastname: Galli-Resta
authors.forename: Antonello
authors.initials: A
authors.lastname: Fadda
authors.forename: Lucia
authors.initials: L
authors.lastname: Ziccardi
authors.forename: Marco
authors.initials: M
authors.lastname: Piccardi
authors.forename: Giancarlo
authors.initials: G
authors.lastname: Iarossi
authors.forename: Giovanni
authors.initials: G
authors.lastname: Resta
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D018450:Disease Progression; D004596:Electroretinography / Q000379:methods*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D017949:Retinal Cone Photoreceptor Cells / Q000502:physiology*; D012174:Retinitis Pigmentosa / Q000503:physiopathology*; D013997:Time Factors; D014792:Visual Acuity; D014794:Visual Fields