Use of microperimetry to evaluate hydroxychloroquine and chloroquine retinal toxicity

To check the ability of microperimetry to detect early retinal damage in patients with rheumatism taking hydroxychloroquine (HCQ), chloroquine (CQ), or both, and to describe the microperimetric alterations attributable to these drugs and their correlation with some clinical variables.

Controlled cross-sectional study.

Patient group was 209 patients taking HCQ or CQ. Control group was 204 individuals not taking antimalarials. Exclusion criterion was other diseases that could alter microperimetry.

An ophthalmic examination and a microperimetry were performed on all individuals. Outcomes measured were average threshold, fixation stability, and macular integrity. Information about patient weight, height, main diagnosis, daily and cumulative dose, and creatinine, bilirubin, and transaminases levels were collected. Analysis of variance, t tests, and a regression analysis were carried out to detect differences between groups.

Significant differences in microperimetry indexes were detected between cases and control subjects, between patients of different age groups, and between patients taking CQ and HCQ. Significant differences were also detected in retinal sensitivity between patients overdosed for CQ, but not for those overdosed for HCQ. Daily overdosing per ideal weight alone cannot explain retinal toxicity, although the effect of cumulative dose in macular sensibility is significant to explain both average threshold and macular integrity.

Microperimetry is an accurate tool for detecting early macular hyposensibility caused by CQ and HCQ. Microperimetry indexes of retinal sensibility are worse in elderly patients taking these drugs and in short-stature patients taking CQ. A high cumulative dose is an important factor in explaining retinal hyposensibility on microperimetry.