Selective thinning of the perifoveal inner retina as an early sign of hydroxychloroquine retinal toxicity.

PURPOSE: To evaluate macular thickness profiles using spectral-domain optical coherence tomography (SDOCT) and image segmentation in patients with chronic exposure to hydroxychloroquine. METHODS: This study included eight patients with chronic exposure to hydroxychloroquine (group 1) and eight controls (group 2). Group 1 patients had no clinically evident retinal toxicity. All subjects underwent SDOCT imaging of the macula. An image segmentation technique was used to measure thickness of six retinal layers at 200 microm intervals. A mixed-effects model was used for multivariate analysis. RESULTS: By measuring total retinal thickness either at the central macular (2800 microm in diameter), the perifoveal region 1200-microm-width ring surrounding the central macula), or the overall macular area (5200 microm in diameter), there were no significant differences in the thickness between groups 1 and 2. On an image segmentation analysis, selective thinning of the inner plexiform+ganglion cell layers (P=0.021) was observed only in the perifoveal area of the patients in group 1 compared with that of group 2 by using the mixed-effects model analysis. CONCLUSION: Our study results suggest that chronic exposure to hydroxychloroquine is associated with thinning of the perifoveal inner retinal layers, especially in the ganglion cell and inner plexiform layers, even in the absence of functional or structural clinical changes involving the photoreceptor or retinal pigment epithelial cell layers. This may be a contributing factor as the reason most patients who have early detectable signs of drug toxicity present with paracentral or pericentral scotomas.

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

PURPOSE: 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. METHODS: 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. RESULTS: 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). CONCLUSIONS: 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.

Retinal nerve fibre layer thickness analysis in X-linked retinoschisis using Fourier-domain OCT.

PURPOSE: To evaluate the presence of retinal nerve fibre layer (RNFL) defects in patients with X-linked retinoschisis (XLRS) using high-speed, high-resolution, Fourier domain OCT (FD-OCT). METHODS: Twenty-four patients with XLRS seen by the authors were enrolled in the study. All patients underwent a complete eye examination. FD-OCT was performed using Optovue technology. A quadrant of the RNFL was considered to be thinned if at least two of the four segments in the quadrant were reduced in thickness. RESULTS: The average age of the 24 patients in the study was 28.8+/-14.7 years. Thinning of the RNFL in one quadrant was seen in 10 patients (41.7%), and thinning in two or more quadrants was seen in 8 patients (33.3%). Thinning in the inferior quadrant was most commonly seen and was observed in 12 patients (50%), followed by the temporal quadrant in 8 patients (33.3%), nasal quadrant in 4 patients (16.7%), and the superior quadrant in 4 patients (16.7%). CONCLUSIONS: Among our 24 patients with XLRS, 15 patients (62.5%) showed a thinning of the RNFL in one or more quadrants in at least one eye and 9 patients (37.5%) in both eyes. High-speed, high-resolution FD-OCT may be useful to determine the presence of possible changes in RNFL thickness in patients with XLRS. Reductions in RNFL thickness in such patients could be relevant in their selection for future therapeutic trials.