title: Correlation between SD-OCT, immunocytochemistry and functional findings in an animal model of retinal degeneration.
abstract: OBJECTIVE
  The P23H rhodopsin mutation is an autosomal dominant cause of retinitis pigmentosa (RP). The degeneration can be tracked using different anatomical and functional methods. In our case, we evaluated the anatomical changes using Spectral-Domain Optical Coherence Tomography (SD-OCT) and correlated the findings with retinal thickness values determined by immunocytochemistry.
  
  
  METHODS
  Pigmented rats heterozygous for the P23H mutation, with ages between P18 and P180 were studied. Function was assessed by means of optomotor testing and ERGs. Retinal thicknesses measurements, autofluorescence and fluorescein angiography were performed using Spectralis OCT. Retinas were studied by means of immunohistochemistry.
  
  
  RESULTS
  Between P30 and P180, visual acuity decreased from 0.500 to 0.182 cycles per degree (cyc/deg) and contrast sensitivity decreased from 54.56 to 2.98 for a spatial frequency of 0.089 cyc/deg. Only cone-driven b-wave responses reached developmental maturity. Flicker fusions were also comparable at P29 (42 Hz). Double flash-isolated rod-driven responses were already affected at P29. Photopic responses revealed deterioration after P29.A reduction in retinal thicknesses and morphological modifications were seen in OCT sections. Statistically significant differences were found in all evaluated thicknesses. Autofluorescence was seen in P23H rats as sparse dots. Immunocytochemistry showed a progressive decrease in the outer nuclear layer (ONL), and morphological changes. Although anatomical thickness measures were significantly lower than OCT values, there was a very strong correlation between the values measured by both techniques.
  
  
  CONCLUSIONS
  In pigmented P23H rats, a progressive deterioration occurs in both retinal function and anatomy. Anatomical changes can be effectively evaluated using SD-OCT and immunocytochemistry, with a good correlation between their values, thus making SD-OCT an important tool for research in retinal degeneration.
authors.affiliation: Department of Physiology, Genetics and Microbiology, University of Alicante Alicante, Spain.
authors.forename: Nicolás
authors.initials: N
authors.lastname: Cuenca
authors.affiliation: Department of Physiology, Genetics and Microbiology, University of Alicante Alicante, Spain.
authors.forename: Laura
authors.initials: L
authors.lastname: Fernández-Sánchez
authors.affiliation: Departments of Ophthalmology and Physiology, University of Alberta Edmonton, AB, Canada.
authors.forename: Yves
authors.initials: Y
authors.lastname: Sauvé
authors.affiliation: Aragon Health Science Institute, IIS Aragon Zaragoza, Aragon, Spain ; Department of Surgery, School of Medicine, University of Zaragoza Zaragoza, Aragon, Spain.
authors.forename: Francisco J
authors.initials: FJ
authors.lastname: Segura
authors.affiliation: Bioengineering Institute, Miguel Hernandez University, Elche Alicante, Spain.
authors.forename: Gema
authors.initials: G
authors.lastname: Martínez-Navarrete
authors.affiliation: Bloss Group Company, Spain and Heidelberg Engineering Gmbh Heidelberg, Germany.
authors.forename: José Manuel
authors.initials: JM
authors.lastname: Tamarit
authors.affiliation: Aragon Health Science Institute, IIS Aragon Zaragoza, Aragon, Spain ; Department of Physiology, University of Zaragoza Zaragoza, Aragon, Spain.
authors.forename: Lorena
authors.initials: L
authors.lastname: Fuentes-Broto
authors.affiliation: Aragon Health Science Institute, IIS Aragon Zaragoza, Aragon, Spain ; Department of Applied Physics, University of Zaragoza Zaragoza, Aragon, Spain.
authors.forename: Ana
authors.initials: A
authors.lastname: Sanchez-Cano
authors.affiliation: Aragon Health Science Institute, IIS Aragon Zaragoza, Aragon, Spain ; Department of Surgery, School of Medicine, University of Zaragoza Zaragoza, Aragon, Spain ; Department of Ophthalmology, Lozano Blesa University Hospital Zaragoza, Aragon, Spain.
authors.forename: Isabel
authors.initials: I
authors.lastname: Pinilla
keywords: P23H rat; autofluorescence; electroretinogram; immunohistochemistry; optical coherence tomography; retinal degeneration; retinitis pigmentosa; visual acuity