title: Docosahexaenoic Acid Slows Visual Field Progression in X-Linked Retinitis Pigmentosa: Ancillary Outcomes of the DHAX Trial.
abstract: OBJECTIVE
  Docosahexaenoic acid (DHA) was supplemented in a single-site, placebo-controlled, randomized clinical trial designed to slow vision loss associated with X-linked retinitis pigmentosa (XLRP); the DHAX Trial. We previously reported no significant differences between supplemented and placebo groups in intent-to-treat analysis of primary ERG outcomes. Assessed herein are hypothesis-generating measures of ancillary visual function outcomes in participants fully adhering to trial protocol.
  
  
  METHODS
  Male participants with XLRP (range, 7-31 years) received 30 mg DHA/kg/d (n = 29) or placebo (n = 22) for 4 years. Visual outcomes were measured annually and red blood cell (RBC) DHA determined every 6 months.
  
  
  RESULTS
  Oral DHA supplementation increased mean RBC-DHA levels by 4-fold (P < 0.0001) over placebo. No group differences in progression were found for visual acuity (P = 0.11), shape discrimination (P = 0.18), or fundus appearance (P = 0.70). Optical coherence tomography (OCT) became available during year 2 of the trial; no group differences were seen in ellipsoid zone constriction (P = 0.87) over 2 years. Yearly rates of progression were reduced for dark-adapted thresholds (P = 0.06) and visual field sensitivity for foveal, macular, peripheral, total, and ellipsoid zone regions by DHA supplementation (P = 0.039, P = 0.031, P < 0.0001, P < 0.0001, and P = 0.033). Rates of visual field sensitivity decline were dependent on RBC-DHA (P = 0.046 to <0.0001).
  
  
  CONCLUSIONS
  Supplementation of DHA significantly elevated blood DHA levels and reduced the rate of progression in final dark-adapted thresholds and visual field sensitivity. From the relationship between RBC-DHA and the rate of field sensitivity loss, we can extrapolate that an RBC-DHA level of 17% could minimize the decline in field sensitivity. (ClinicalTrials.gov number, NCT00100230.)
authors.affiliation: Retina Foundation of the Southwest, Dallas, Texas, United States 2Department of Ophthalmology, University of Texas Southwestern Medical Center, Dallas, Texas, United States.
authors.forename: Dennis R
authors.initials: DR
authors.lastname: Hoffman
authors.affiliation: Retina Foundation of the Southwest, Dallas, Texas, United States 2Department of Ophthalmology, University of Texas Southwestern Medical Center, Dallas, Texas, United States.
authors.forename: Dianna K
authors.initials: DK
authors.lastname: Hughbanks-Wheaton
authors.affiliation: Texas Retina Associates, Dallas, Texas, United States.
authors.forename: Rand
authors.initials: R
authors.lastname: Spencer
authors.affiliation: Texas Retina Associates, Dallas, Texas, United States.
authors.forename: Gary E
authors.initials: GE
authors.lastname: Fish
authors.affiliation: Center for Teaching Excellence, Southern Methodist University, Dallas, Texas, United States.
authors.forename: N Shirlene
authors.initials: NS
authors.lastname: Pearson
authors.affiliation: Retina Foundation of the Southwest, Dallas, Texas, United States 2Department of Ophthalmology, University of Texas Southwestern Medical Center, Dallas, Texas, United States.
authors.forename: Yi-Zhong
authors.initials: YZ
authors.lastname: Wang
authors.affiliation: Retina Foundation of the Southwest, Dallas, Texas, United States.
authors.forename: Martin
authors.initials: M
authors.lastname: Klein
authors.affiliation: Retina Foundation of the Southwest, Dallas, Texas, United States.
authors.forename: Alison
authors.initials: A
authors.lastname: Takacs
authors.affiliation: Retina Foundation of the Southwest, Dallas, Texas, United States.
authors.forename: Kirsten G
authors.initials: KG
authors.lastname: Locke
authors.affiliation: Retina Foundation of the Southwest, Dallas, Texas, United States 2Department of Ophthalmology, University of Texas Southwestern Medical Center, Dallas, Texas, United States.
authors.forename: David G
authors.initials: DG
authors.lastname: Birch
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D018450:Disease Progression; D004281:Docosahexaenoic Acids / Q000627:therapeutic use*; D005556:Form Perception / Q000187:drug effects; D005654:Fundus Oculi; D040181:Genetic Diseases, X-Linked / Q000188:drug therapy*; D006801:Humans; D008297:Male; D012174:Retinitis Pigmentosa / Q000188:drug therapy* / Q000235:genetics; D014794:Visual Fields / Q000187:drug effects; D055815:Young Adult
chemical_list: D004281:Docosahexaenoic Acids