title: Localization of damage in progressive hydroxychloroquine retinopathy on and off the drug: inner versus outer retina, parafovea versus peripheral fovea.
abstract: OBJECTIVE
  To evaluate the relative involvement of inner and outer retina in hydroxychloroquine (HCQ) retinopathy while on the drug, and after drug cessation, using data from spectral-domain optical coherence tomography (SD-OCT).
  
  
  METHODS
  A total of 102 SD-OCT scans were obtained from 11 patients (classified as having early, moderate, or severe stages of toxicity) over a period of 4 years after cessation of HCQ. The inner and outer retina boundaries were identified automatically to measure thickness and characterize progression topographically.
  
  
  RESULTS
  The segmentation of retinal layers was verified in SD-OCT cross-sections for all eyes and scans included in this study (a total of 102 scans). Topographic analysis showed that inner retina was not involved in HCQ toxicity to any meaningful degree, either between stages of retinopathy or after the drug is stopped. The characteristic bull's eye pattern of outer macula thinning appears when comparing moderate retinopathy (before any RPE damage) to the early stage. Later damage, as toxicity evolved to a severe stage, was diffuse across most of the macula. If the drug was stopped at an early or moderate stage, progression was limited to the first year and occurred diffusely without parafoveal localization.
  
  
  CONCLUSIONS
  Hydroxychloroquine retinopathy primarily involves outer retina (photoreceptors). Outer retinal thinning while using HCQ initially involves the parafovea, but becomes diffuse across the macula as damage progresses or after drug cessation. When HCQ is stopped at an early or moderate stage (before RPE damage), progression seems to be limited to the first year.
authors.affiliation: Department of Radiology Stanford University, Stanford, California, United States.
authors.forename: Luis
authors.initials: L
authors.lastname: de Sisternes
authors.affiliation: Department of Ophthalmology, Byers Eye Institute at Stanford, Stanford University School of Medicine, Palo Alto, California, United States.
authors.forename: Julia
authors.initials: J
authors.lastname: Hu
authors.affiliation: Department of Radiology Stanford University, Stanford, California, United States 3Department of Medicine (Biomedical Informatics), Stanford University, Stanford, California, United States.
authors.forename: Daniel L
authors.initials: DL
authors.lastname: Rubin
authors.affiliation: Department of Ophthalmology, Byers Eye Institute at Stanford, Stanford University School of Medicine, Palo Alto, California, United States.
authors.forename: Michael F
authors.initials: MF
authors.lastname: Marmor
mesh_terms: D000328:Adult; D000368:Aged; D000962:Antimalarials / Q000009:adverse effects*; D018501:Antirheumatic Agents / Q000009:adverse effects*; D005260:Female; D005584:Fovea Centralis / Q000473:pathology*; D006801:Humans; D006886:Hydroxychloroquine / Q000009:adverse effects*; D008297:Male; D008875:Middle Aged; D012164:Retinal Diseases / Q000139:chemically induced* / Q000473:pathology*; D041623:Tomography, Optical Coherence
chemical_list: D000962:Antimalarials; D018501:Antirheumatic Agents; D006886:Hydroxychloroquine