Evaluation of optical coherence tomography angiography parameters in patients treated with Hydroxychloroquine

Abstract

Background One of the major side effects of Hydroxychloroquine (HCQ) is retinopathy. The aim of this study was to evaluate the Optical coherence tomography angiography (OCTA) parameters in a group of patients who have Hydroxychloroquine-induced retinopathy based on Multifocal electroretinography (mfERG) with a group who do not have retinopathy. Method This is a Cross-Sectional Study. In this study, patients with Rheumatoid arthritis (RA) or Systemic lupus erythematosus (SLE) who had been taking Hydroxychloroquine for at least 7 years were included. MfERG and OCTA imaging were performed for all patients. Patients were divided into Normal mfERG and Abnormal mfERG groups based on mfERG results. OCTA parameters were studied in these two groups. Result Sixty-one patients (61 eyes) were included. Forty-one patients had SLE and 20 patients had RA. Forty patients (66.7%) had Abnormal mfERG. The mean vascular density (VD) in Superficial capillary plexus (SCP) layer was not significantly different between Normal mfERG and Abnormal mfERG groups (P-Value> 0.05). Mean VD in SCP layer was not significantly different between Normal mfERG and Abnormal mfERG groups (P-Value> 0.05). In RA subgroup, mean VD in SCP layer in PeriFovea region in Abnormal mfERG group was significantly lower than normal group (P-Value < 0.05). Mean VD in deep capillary plexus (DCP) layer in Whole Image, Superior Hemi, Inferior Hemi, PeriFovea area in Abnormal mfERG group was significantly lower than normal group (P-Value < 0.05). This discrepancy was also observed in the RA subgroup but not in the SLE subgroup. The mean of none of the parameters of foveal avascular zone (FAZ) (mm2), Flow Area of Outer Retina (mm2) and Flow Area of Choriocapillaris (mm2) were not statistically significant between the groups Abnormal mfERG and Normal mfERG. (p-value> 0.05). Conclusion VD in the DCP layer decreased in abnormal mfERG patients compared to patients with normal mfERG. But it seems that VD in SCP layer, FAZ Area and Flow Area are similar in both groups. OCTA may be used as a non-invasive tool in the diagnosis of early stages of HCQ-induced retinopathy, especially in RA patients, but further studies are needed.

New insights in pathogenic mechanism of hydroxychloroquine retinal toxicity through optical coherence tomography angiography analysis

“…3,4,6,22 The majority of the authors conclude that VD decreased in SCP, DCP and CC in patients taking HCQ for more than 5 years. 1,3,4,6,11,13,18,22,23 In our investigation, we observed that VD in the temporal quadrant of SCP, and total VD and superior VD in MCP were increased in the low-risk group compared to control patients. Moreover, VD in the nasal area of SCP, parafoveal and nasal VD in MCP, and parafoveal and inferior VD of TCP were increased in the highrisk group compared to control group.…”

“…These results agree with previous research. 1,3,4,6,11,13,18,22,23 It is known that tall RPE cells with increased melanin contribute to the formation of FAZ. We suggest that the binding of HCQ to melanin of RPE cells may enlarge the FAZ area.…”

“…Nonetheless, retinal toxicity is a major and potentially irreversible side effect of this drug, occurring in approximately 6% of patients receiving HCQ therapy for more than 5 years. [1][2][3][4][5] The mechanism of retinal toxicity is not well understood. HCQ is likely to bind to melanin within retinal pigment epithelium (RPE) and choroid, which are melaninrich ocular tissues.…”

“…Risk factors associated with the development of HCQ retinopathy include daily dose greater than 5 mg/kg, cumulative dose greater than 1000 g, duration of use over 5 years, elderly age, kidney or liver dysfunction, preexisting maculopathy or concomitant use of tamoxifen. 1,[6][7][8] Early detection of HCQ retinal toxicity is crucial in order to avoid catastrophic and irreversible visual loss, since the toxicity may progress despite discontinuation of treatment because a continued reservoir is present and clearance from the body can take several months. It has been reported that central vision can be preserved if the damage is detected before RPE alterations occur.…”

Novel imaging techniques for hydroxychloroquine retinopathy

“…Accordingly, Bulut et al ( 27 ) suggested that OCTA evaluation has the potential to detect hydroxychloroquine-induced retinal toxicity at an early stage. A recent study showed that the mean vascular density in the deep capillary plexus layer decreased in those showing abnormal mfERG recordings, indicating a potential role of OCTA in the early detection of retinopathy ( 28 ). Moreover, another recent report showed a large number of signal void zones in the choriocapillaris of patients with hydroxychloroquine retinopathy, which were more remarkable in those with severe disease ( 15 ).…”