Spectral domain optical coherence tomography for early detection of retinal alterations in patients using hydroxychloroquine

OBJECTIVE: To determine whether early toxic effects from hydroxychloroquine (HCQ) could be detected by spectral-domain optical coherence tomography (SD-OCT) before symtomatic visual loss occured. MATERIALS AND METHODS: Fifteen subjects with a history of the chronic use of hydroxychloroquine monotherapy for less than five years without fundus changes (group 1) and 15 visually normal healthy subjects (group 2) were enrolled in this study. All participants underwent systemic and ocular examination, visual field testing, and macular scan imaging using SD-OCT. RESULTS: There were no significant differences in sex and ages between the groups (P > 0.05). Mean duration of HCQ usage in group 1 was 2.5 ± 1.34 (range:1-5) years. Visual field testing with central 10-2 threshold program was normal in all subjects. Inner retinal thickness in parafoveal and perifoveal area were found to be significantly lower in group 1 compared to group 2 (P < 0.01 for perifoveal, P < 0.05 for parafoveal retinal measurements). However, significant thinning was demonstrated only in full retinal thickness of perifoveal area in group 1 compared to group 2 (P: 0.013). Parafoveal and perifoveal inner retinal thickness measurements of inferior quadrants were significantly reduced in group 1 compared to group 2 (P < 0.01). CONCLUSION: Significant thinning of inner retinal layer especially in parafoveal and perifoveal areas in the absence of clinical fundus changes was observed in our study. We consider that SD-OCT may determine when inner retinal thinning starts in these patients and may contribute a quantitative approach to the early diagnosis and progression of retinal changes.