title: ABCA4-associated retinal degenerations spare structure and function of the human parapapillary retina.
abstract: OBJECTIVE
  To study the parapapillary retinal region in patients with ABCA4-associated retinal degenerations.
  
  
  METHODS
  Patients with Stargardt disease or cone-rod dystrophy and disease-causing variants in the ABCA4 gene were included. Fixation location was determined under fundus visualization, and central cone-mediated vision was measured. Intensity and texture abnormalities of autofluorescence (AF) images were quantified. Parapapillary retina of an eye donor with ungenotyped Stargardt disease was examined microscopically.
  
  
  RESULTS
  AF images ranged from normal, to spatially homogenous abnormal increase of intensity, to a spatially heterogenous speckled pattern, to variably sized patches of low intensity. A parapapillary ring of normal-appearing AF was visible at all disease stages. Quantitative analysis of the intensity and texture properties of AF images showed the preserved region to be an annulus, at least 0.6 mm wide, surrounding the optic nerve head. A similar region of relatively preserved photoreceptor nuclei was apparent in the donor retina. In patients with foveal fixation, there was better cone sensitivity at a parapapillary locus in the nasal retina than at the same eccentricity in the temporal retina. In patients with eccentric fixation, approximately 30% had a preferred retinal locus in the parapapillary retina.
  
  
  CONCLUSIONS
  Human retinal degenerations caused by ABCA4 mutations spare the structure of retina and RPE in a circular parapapillary region that commonly serves as the preferred fixation locus when central vision is lost. The retina between fovea and optic nerve head could serve as a convenient, accessible, and informative region for structural and functional studies to determine natural history or outcome of therapy in ABCA4-associated disease.
authors.affiliation: Scheie Eye Institute, Department of Ophthalmology, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA. cideciya@mail.med.upenn.edu
authors.forename: Artur V
authors.initials: AV
authors.lastname: Cideciyan
authors.forename: Malgorzata
authors.initials: M
authors.lastname: Swider
authors.forename: Tomas S
authors.initials: TS
authors.lastname: Aleman
authors.forename: Alexander
authors.initials: A
authors.lastname: Sumaroka
authors.forename: Sharon B
authors.initials: SB
authors.lastname: Schwartz
authors.forename: Marisa I
authors.initials: MI
authors.lastname: Roman
authors.forename: Ann H
authors.initials: AH
authors.lastname: Milam
authors.forename: Jean
authors.initials: J
authors.lastname: Bennett
authors.forename: Edwin M
authors.initials: EM
authors.lastname: Stone
authors.forename: Samuel G
authors.initials: SG
authors.lastname: Jacobson
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000235:genetics*; D005260:Female; D006801:Humans; D007834:Lasers; D008875:Middle Aged; D009154:Mutation; D009887:Ophthalmoscopy / Q000379:methods; D009898:Optic Disk / Q000473:pathology*; D012160:Retina / Q000473:pathology*; D012162:Retinal Degeneration / Q000175:diagnosis* / Q000235:genetics*; D014792:Visual Acuity
chemical_list: C056475:ABCA4 protein, human; D018528:ATP-Binding Cassette Transporters