Effects of chronic exposure to hydroxychloroquine or chloroquine on inner retinal structures

To evaluate peripapillary retinal nerve fibre layer (RNFL) thickness and macular inner and outer retinal thickness using spectral domain optical coherence tomography (Sd-OCT) in patients with chronic exposure to hydroxychloroquine or chloroquine.

Subjects were divided into three groups: Group I, four patients with hydroxychloroquine or chloroquine toxicity with abnormal fundus; Group II, eight patients with chronic exposure without fundus changes; and Group III, eight visually normal controls. Peripapillary RNFL thinning for an individual quadrant was based on measurements of less than the 5th percentile from at least two out of four segments in the quadrant. Macular scans on Groups I and II were carried out to compare the thickness of the inner, outer, and full-thickness retina to that of Group III.

The mean ages in Groups I, II, and III were 57.6+/-8.0, 54.9+/-11.0 and 53.7+/-10.5 years, respectively (P=0.83). Median (range) duration of exposure was 7.5 (5-12) years in Group I, and was 10 (6-35) years in Group II. Seven (88%) of eight eyes in Group I showed peripapillary RNFL thinning in at least one quadrant, whereas none of Groups II and III did so. Using macular scans, Group I showed significant thinning of the inner, outer, and full-thickness retina compared to Group III (P<0.001). Group II had significant thinning only of the inner retina compared to Group III (P<0.001).

OCT is useful to detect peripapillary RNFL thinning in clinically evident retinopathy, and selective thinning of the macular inner retina can be detected in the absence of clinically apparent fundus changes.