Early hydroxychloroquine retinal toxicity enhanced by laser flare-cell meter

Purpose The aim of this study is the evaluation of the electro-oculogram (EOG) against the laser flare-cell meter methodology (LFM) in early detection of hydroxychloroquine retinal toxicity. Several studies have showed that hydroxychloroquine, an antiprotozoal drug used in the treatment of malaria and various rheumatic diseases, can cause severe visual loss due to a toxic effect on the outer retina and the retinal pigment epithelium (EPR). Methods We enrolled 12 patients (3 males and 9 females) with rheumatoid arthritis (10 patients) and systemic lupus erythematosus (2 patients) in therapy with hydroxychloroquine without retinal toxicity, and 12 health controls (5 males and 7 females). EOG and LFM with a laser flare-cell meter instruments (FM-500, Kowa, Tokio, Japan).were performed in all patients and in health controls. The Student’s t test and the Bartlett’s correlation test was performed to compare the results of EOG and LFM with the hydroxychloroquine dose considering significant a p<0.05. Results The Arden ratio was 188.75±48.94 in patients and 288.33±32.42 in controls (p=0,262); the LFM was 45.80±15.33 vs. 6.31±1.12 photons/ms(p<0.030). The Bartlett’s test showed a strong correlation (p<0.022) between the flare and the total hydroxychloroquine dose (394.16±53.84 mg). Conclusion The flare is an index of anterior segment subclinical inflammation. The proteins level increase in many pathologies, especially in case of an alteration of pigmented cells of iris and ciliar body. These cells have the same origin of EPR and could be damaged by the hydroxychloroquine. In conclusion we can say that the laser flare-cell meter could be an easier, quickly and more sensibly exam than EOG to detect early hydroxychloroquine toxicity.