Evaluation of cone photoreceptor density using adaptive optics retinal imaging in patients under treatment with hydroxychloroquine

Abstract Purpose Hydroxychloroquine is a common treatment of many inflammatory diseases and is sometimes responsible of irreversible macular toxicity. Early screening is essential. Our study aimed to evaluate feasibility of adaptive optics imaging in this population and to measure parafoveal cone density. Methods Patients under treatment or consulting for a pre‐treatment checkup where included. A complete ophthalmologic examination was performed, as well as a high‐definition fundus photography using adaptive optics retinal camera rtx‐1™ (Imagine Eyes, Orsay, France). Cumulative dose of hydroxychloroquine was calculated. Parafoveal cone density, cellular spacing, and percentage of hexagonal cells calculated using Voronoi diagrams were calculated using AODetect v0.1 software (Imagine Eyes, Orsay, France). Results Sixty eyes of 30 patients (27 females, 3 males) were imaged. There was a significative correlation between maximal parafoveal cone density and cumulative dose of hydroxychloroquine. (R² = 0,20, p = 0,029). This relation was also found with cellular spacing (R² : 0,2, p = 0,03) and hexagonal cells percentage estimated on Voronoi diagram (R² : 0,19, p = 0,03). By contrast, no statistically significative difference was found by comparing the group “cumulative dose < 1000g” with the group “cumulative dose > 1000g (Mann‐Whitney test,p = 0,14). Conclusion Parafoveal cone density mesure using adaptive optics retinal camera is achievable in this population. Our study seems to highlight a relation between cumulative dose and parafoveal cone density. Age and axial length are possible confusion factors that could not be studied in this study.