Scotoma analysis of 10–2 visual field testing with a red target in screening for hydroxychloroquine retinopathy

OBJECTIVE: To quantify the variability of scotomas detected by 10–2 visual field (VF) testing with a red target in patients taking hydroxychloroquine without and with retinopathy. DESIGN: Retrospective review of clinical charts and VFs. METHODS: Twenty-four patients taking hydroxychloroquine without retinopathy, and eight patients taking hydroxychloroquine with retinopathy were tested in this study. Retinopathy was defined by annular scotomas on 10–2 VF testing with corroborative spectral domain optical coherence tomographic outer retinal changes and multifocal electroretinographic changes leading to cessation of hydroxychloroquine or chloroquine. Location and depth of scotoma points on 10–2 VF testing were recorded and their fates followed in serial, reliable 10–2 VFs performed with a red target over time. The main outcome measures for this study were the number of scotoma points and locations, percentage of persistent scotoma points, size of scotomas, location of scotomas, and percentage of scotomas deepening. RESULTS: A median of 3, interquartile range (IQR) (2, 5), scotoma points per VF occurred in patients without retinopathy. A median of 86%, IQR (77, 100), of these resolved on the subsequent field. For patients with retinopathy, a median of 50%, IQR (46, 79), resolved, a difference compared to patients without retinopathy that was significant (P=0.0158). The median percentage of scotoma points in the zone from 2° to 8° from fixation in eyes with retinopathy was 72%, IQR (54, 100), compared to 49%, IQR (40, 54), in eyes without retinopathy (P=0.0069). The number of persistent scotoma locations at the last visit was higher in eyes with retinopathy: 3, IQR (1, 3), versus 0, IQR (0, 1), in patients without retinopathy, P=0.0156. CONCLUSION: Point scotomas are common and variable in 10–2 VF testing with a red target for hydroxychloroquine retinopathy in subjects without retinopathy. Scotoma points in eyes with retinopathy are less variable. The annular zone 2°–8° from fixation was useful for distinguishing the significance of scotoma points. Discriminating eyes with retinopathy from eyes without retinopathy is probably easier using the 10–2 VF with a white target than a red target.