Evaluation of Changes in the Ganglionic Cell Inner Plexiform Layer and Macular Retinal Nerve Fibre Layer in Patients Receiving Hydroxychloroquine

Abstract

Backgrounds: To evaluate changes in the thickness of ganglionic cell-inner plexiform layer and macular retinal nerve fiber layer using ocular coherence tomographyin patients exposed to hydroxychloroquine .Methods: This was a retrospective, cross-sectional study of patients on hydroxychloroquine therapy. Ocular coherence tomography images showing of ganglionic cell-inner plexiform cell layer and macular retinal nerve fiber layer thickness were obtained and compared to those of the control groups. The relationship between the thickness of of ganglionic cell-inner plexiform and macular retinal nerve fibre layer and the duration and cumulative dose of hydroxychloroquine was evaluated.Results: In all, 219 patients were included in this study; the mean age was 43.38 (±17.39) years. The study group comprised 100 (20 male and 80 female) patients, with a mean age of 45.28 (± 12.24) years; the control group had 119 patients (44 males and 75 females), with a mean age of 41.79 (± 20.67) years, with no significant difference in age between the groups (p = 0.123). There was a significant difference in mean of ganglionic cell-inner plexiform thickness between the study and control groups (85.6+/- 8 μm ) vs. (88.6+/-6 μm ) (p = 0.006), with a mean difference of 0.31 (95% confidence interval). The average RNFL thickness was similar in the study and control groups, 28.8±2.5 μm (range: 23 – 38) and 29.2±2.8 μm (range: 22 – 35) respectively, (p = 0.389). There was no significant correlation between of ganglionic cell-inner plexiform and macular retinal nerve fibre layer with daily dose (p = 0.229) or cumulative dose of hydroxychloroquine (p = 0.678). Conclusion : The average thickness of ganglionic cell -inner plexiform cell layer was significantly lower in those taking hydroxychloroquine than in controls. Thinning of this layer could be an early indicator of retinal toxicity before the appearance of clinical retinopathy. However, thickness of the macular retinal nerve fibre laye showed no decrease in hydroxychloroquine users and did not correlate with the duration or cumulative doses of hydroxychloroquine. Therefore, macular retinal nerve fibre layer thickness is not a useful biomarker for the early detection of hydroxychloroquine retinal toxicity.