Early effect of hydroxychloroquine therapy: relationship between cumulative dose and retinal thickness

Electrophysiological and SD-OCT findings in patients receiving chloroquine therapy in relation to cumulative dosage and duration of treatment

PURPOSE

Assessment of multifocal ERG (mfERG) changes in patients treated with chloroquine and their correlation with morphological abnormalities, detected by spectral-domain optical coherence tomography in relation to cumulative dosage.

METHODS

Data from 37 eyes of 20 patients were retrospectively collected, and one randomly selected eye per patient was considered for statistical analysis. Eyes were divided into three groups according to mfERG and visual acuity findings: normal, early and advanced maculopathy. Functional measures of the first three mfERG rings were compared with retinal thickness measures of the corresponding OCT ETDRS circles. Data on cumulative dose and duration of therapy were also evaluated.

RESULTS

The mean mfERG values progressively decreased according to the stage of the disease. In particular in the early maculopathy group, amplitudes were significantly reduced in all the three central rings. The mean ring ratio R1/R2 was abnormal only in the early maculopathy group. OCT thickness measures were significantly lower in all the three ETDRS circles in the advanced maculopathy group, and in the paracentral circle in the early maculopathy group. Considering all the eyes, there was a statistically significant correlation between functional and morphological values (p < 0.001). High chloroquine cumulative dosages were always associated with retinal toxic effects, whereas lower cumulative dosages generated different levels of toxicity.

CONCLUSIONS

This study shows a strong association between mfERG ring values and the corresponding OCT thickness measures; however, mfERG may enhance early detection of functional changes in patients treated with chloroquine, especially in ambiguous cases. At low chloroquine cumulative dosages, different subjects might have different susceptibilities to the drug.

Structural and Functional Characterization of the Retinal Effects of Hydroxychloroquine Treatment in Healthy Eyes

PURPOSE

To evaluate the influence of hydroxychloroquine in visual field and retinal layer thickness.

METHODS

This is a retrospective cross-sectional study. Patients taking hydroxychloroquine without signs of hydroxychloroquine retinopathy were included. Optical coherence tomography segmentation was used to obtain the ETDRS map thickness of each retinal layer. Groups were divided into short-term (< 5 years) and long-term (≥5 years) drug use.

RESULTS

We included 93 eyes of 93 patients (short-term: 25 eyes; long-term: 68 eyes). The inner nuclear layer (INL) was thinner in the long-term group (32.86 ± 2.12 vs. 34.14 ± 2.37 μm; p = 0.014). Considering long-term cases, the parafoveal ganglion cell layer (GCL) showed an inverse correlation with cumulative dose (r = -0.37; p < 0.001). After adjusting for confounders, parafoveal ganglion cell complex thickness was associated with cumulative dose (β = -0.239; p = 0.011). The parafoveal outer retina and visual field indices were similar between groups and did not correlate with cumulative dose.

CONCLUSION

Hydroxychloroquine leads to progressive thinning of the parafoveal inner retina, particularly the INL and GCL. Visual field indices do not reflect the long-term effects of the drug.