title: Macular function in macular degenerations: repeatability of microperimetry as a potential outcome measure for ABCA4-associated retinopathy trials.
abstract: OBJECTIVE
  To measure macular visual function in patients with unstable fixation, to define the photoreceptor source of this function, and to estimate its test-retest repeatability as a prerequisite to clinical trials.
  
  
  METHODS
  Patients (n = 38) with ABCA4-associated retinal degeneration (RD) or with retinitis pigmentosa (RP) were studied with retina-tracking microperimetry along the foveo-papillary profile between the fovea and the optic nerve head, and point-by-point test-retest repeatability was estimated. A subset with foveal fixation was also studied with dark-adapted projection perimetry using monochromatic blue and red stimuli along the horizontal meridian.
  
  
  RESULTS
  Macular function in ABCA4-RD patients transitioned from lower sensitivity at the parafovea to higher sensitivity in the perifovea. RP patients had the inverse pattern. Red-on-red microperimetric sensitivities successfully avoided ceiling effects and were highly correlated with absolute sensitivities. Point-by-point test-retest limits (95% confidence intervals) were ±4.2 dB; repeatability was not related to mean sensitivity, eccentricity from the fovea, age, fixation location, or instability. Repeatability was also not related to the local slope of sensitivity and was unchanged in the parapapillary retina.
  
  
  CONCLUSIONS
  Microperimetry allows reliable testing of macular function in RD patients without foveal fixation in longitudinal studies evaluating natural disease progression or efficacy of therapeutic trials. A single estimate of test-retest repeatability can be used to determine significant changes in visual function at individual retinal loci within diseased regions that are homogeneous and those that are heterogeneous and also in transition zones at high risk for disease progression.
authors.affiliation: Scheie Eye Institute, Department of Ophthalmology, Perelman School of Medicine, 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: Willam J
authors.initials: WJ
authors.lastname: Feuer
authors.forename: Sharon B
authors.initials: SB
authors.lastname: Schwartz
authors.forename: Robert C
authors.initials: RC
authors.lastname: Russell
authors.forename: Janet D
authors.initials: JD
authors.lastname: Steinberg
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* / Q000378:metabolism; D000293:Adolescent; D000328:Adult; D002648:Child; D002986:Clinical Trials as Topic; D004247:DNA / Q000235:genetics*; D003623:Dark Adaptation; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008268:Macular Degeneration / Q000175:diagnosis* / Q000235:genetics / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D009154:Mutation; D012162:Retinal Degeneration / Q000175:diagnosis* / Q000235:genetics / Q000503:physiopathology; D041623:Tomography, Optical Coherence; D014792:Visual Acuity; D058609:Visual Field Tests; D014794:Visual Fields / Q000502:physiology*; D055815:Young Adult
chemical_list: C056475:ABCA4 protein, human; D018528:ATP-Binding Cassette Transporters; D004247:DNA