title: Selective thinning of the perifoveal inner retina as an early sign of hydroxychloroquine retinal toxicity.
abstract: OBJECTIVE
  To evaluate macular thickness profiles using spectral-domain optical coherence tomography (SDOCT) and image segmentation in patients with chronic exposure to hydroxychloroquine.
  
  
  METHODS
  This study included eight patients with chronic exposure to hydroxychloroquine (group 1) and eight controls (group 2). Group 1 patients had no clinically evident retinal toxicity. All subjects underwent SDOCT imaging of the macula. An image segmentation technique was used to measure thickness of six retinal layers at 200 microm intervals. A mixed-effects model was used for multivariate analysis.
  
  
  RESULTS
  By measuring total retinal thickness either at the central macular (2800 microm in diameter), the perifoveal region 1200-microm-width ring surrounding the central macula), or the overall macular area (5200 microm in diameter), there were no significant differences in the thickness between groups 1 and 2. On an image segmentation analysis, selective thinning of the inner plexiform+ganglion cell layers (P=0.021) was observed only in the perifoveal area of the patients in group 1 compared with that of group 2 by using the mixed-effects model analysis.
  
  
  CONCLUSIONS
  Our study results suggest that chronic exposure to hydroxychloroquine is associated with thinning of the perifoveal inner retinal layers, especially in the ganglion cell and inner plexiform layers, even in the absence of functional or structural clinical changes involving the photoreceptor or retinal pigment epithelial cell layers. This may be a contributing factor as the reason most patients who have early detectable signs of drug toxicity present with paracentral or pericentral scotomas.
authors.affiliation: Department of Ophthalmology and Visual Sciences, Eye and Ear Infirmary, University of Illinois at Chicago, Chicago, IL 60612, USA.
authors.forename: S
authors.initials: S
authors.lastname: Pasadhika
authors.forename: G A
authors.initials: GA
authors.lastname: Fishman
authors.forename: D
authors.initials: D
authors.lastname: Choi
authors.forename: M
authors.initials: M
authors.lastname: Shahidi
mesh_terms: D000328:Adult; D000368:Aged; D000962:Antimalarials / Q000009:adverse effects*; D018501:Antirheumatic Agents / Q000009:adverse effects*; D002908:Chronic Disease; D005260:Female; D006801:Humans; D006886:Hydroxychloroquine / Q000009:adverse effects*; D008266:Macula Lutea / Q000187:drug effects / Q000473:pathology; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D012160:Retina / Q000187:drug effects* / Q000473:pathology; D012164:Retinal Diseases / Q000139:chemically induced* / Q000473:pathology; D012165:Retinal Ganglion Cells / Q000187:drug effects / Q000473:pathology; D041623:Tomography, Optical Coherence / Q000379:methods
chemical_list: D000962:Antimalarials; D018501:Antirheumatic Agents; D006886:Hydroxychloroquine
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