title: Quantification of Ellipsoid Zone Changes in Retinitis Pigmentosa Using en Face Spectral Domain-Optical Coherence Tomography.
abstract: OBJECTIVE
  New methods are needed to quantify the change in the outer retinal structures in retinitis pigmentosa (RP).
  
  
  OBJECTIVE
  To implement an alternate method for tracking ellipsoid zone (EZ) changes in RP by quantifying the EZ area on en face spectral domain-optical coherence tomographic (SD-OCT) images.
  
  
  METHODS
  Data for this observational case study were collected at the Department of Ophthalmology, University of California, Los Angeles, from May 1 to July 30, 2015, and included SD-OCT images of a subset of patients from the Trial of Oral Valproic Acid for Retinitis Pigmentosa. To be eligible for the en face OCT subanalysis, the preserved EZ area was required to be limited to the SD-OCT scanning field. Cases in which the EZ band extended to the margins of any B-scan or the most superior or inferior B-scan were excluded. The SD-OCT images of all included cases were imported into the manufacturer's software to generate en face images at the level of the EZ. Two certified SD-OCT graders independently delineated the boundaries of the preserved EZ on the en face images.
  
  
  METHODS
  Comparison of the 2 masked gradings of the generated en face images of patients with RP for agreement between the graders and the validity of the method.
  
  
  RESULTS
  Of the 43 available patients with volume SD-OCT data, 45 eyes of 24 patients met the eligibility criteria and were included in this subanalysis. Every patient had 2 visits that were 1 year apart, which included a total of 90 en face OCT images that were graded. The mean (SD) absolute difference and percentage difference between the 2 independent graders for each visit were 0.08 (0.10) mm2 and 4.5% (5.9%), respectively. The EZ area determined by the 2 graders showed excellent agreement with an intraclass correlation coefficient of 0.996 (95% CI, 0.995-0.997; P < .001).
  
  
  CONCLUSIONS
  Quantification of the preserved EZ area on en face SD-OCT images of patients with RP is a valid and reproducible method. En face SD-OCT quantification may be a useful tool for monitoring the EZ changes of patients with advanced RP and a useful outcome measurement variable in therapeutic trials.
authors.affiliation: Doheny Eye Institute, Los Angeles, California2Department of Ophthalmology, David Geffen School of Medicine, University of California, Los Angeles.
authors.forename: Amir H
authors.initials: AH
authors.lastname: Hariri
authors.affiliation: Doheny Eye Institute, Los Angeles, California2Department of Ophthalmology, David Geffen School of Medicine, University of California, Los Angeles.
authors.forename: Hong Yang
authors.initials: HY
authors.lastname: Zhang
authors.affiliation: Doheny Eye Institute, Los Angeles, California.
authors.forename: Alexander
authors.initials: A
authors.lastname: Ho
authors.affiliation: Pacific Ophthalmology Consulting, Portland, Oregon.
authors.forename: Peter
authors.initials: P
authors.lastname: Francis
authors.affiliation: Casey Eye Institute, Oregon Health & Science University, Portland.
authors.forename: Richard G
authors.initials: RG
authors.lastname: Weleber
authors.affiliation: Retina Foundation of the Southwest, Dallas, Texas.
authors.forename: David G
authors.initials: DG
authors.lastname: Birch
authors.affiliation: Division of Epidemiology and Clinical Applications, National Eye Institute, National Institutes of Health, Bethesda, Maryland.
authors.forename: Frederick L
authors.initials: FL
authors.lastname: Ferris
authors.affiliation: Doheny Eye Institute, Los Angeles, California2Department of Ophthalmology, David Geffen School of Medicine, University of California, Los Angeles.
authors.forename: SriniVas R
authors.initials: SR
authors.lastname: Sadda
mesh_terms: D000368:Aged; D004596:Electroretinography; D005260:Female; D018682:GABA Agents / Q000627:therapeutic use; D006801:Humans; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D015203:Reproducibility of Results; D012160:Retina / Q000473:pathology*; D012174:Retinitis Pigmentosa / Q000175:diagnosis* / Q000188:drug therapy; D041623:Tomography, Optical Coherence; D014635:Valproic Acid / Q000627:therapeutic use; D014792:Visual Acuity; D058609:Visual Field Tests
chemical_list: D018682:GABA Agents; D014635:Valproic Acid