LAUSR

Editor, D examethasone intravitreal implant 0.7 mg (DEX 0.7) is successfully used in the treatment of diabetic macular oedema (DME). Subfoveal choroidal thickness has been shown to significantly decrease after injection of DEX 0.7 in eyes with DME (Kim et al. 2016). In this study, we aimed to investigate whether DEX 0.7 injection also had an effect on choroidal volume. Unlike subfoveal choroidal thickness, a decrease in choroidal volume suggests a global rather thana localized effect.Our second objective was to see whether an effect on the choroidal volume can be seen in the unaffected contralateral eye. In this prospective study, we included 16 eyes from 12 patients with DME scheduled for intravitreal DEX 0.7 injection. Exclusion criteria were intravitreal injection with VEGF inhibitors and/or steroids in the study eye six months prior to study inclusion, systemic glucocorticoid treatment six months prior to study inclusion, presence of other retinal disorders in the study eye (excluding diabetic retinopathy) and no or poor view of the fundus. We included seven fellow eyes (7 patients) as control eyes. Inclusion criteria for the fellow eye were presence of diabetic retinopathy (five eyes proliferative, two eyes severe nonproliferative). Exclusion criteria for fellow eyes were current treatment with intravitreal VEGF inhibitors and/or steroids and/ or treatment six months prior to study inclusion, presence of other retinal disorders and no or poor view of the fundus. One untreated fellow eye had to be excluded due to poor image quality. All OCT images were performed using the Spectralis OCT device (Spectralis, Heidelberg Engineering, Heidelberg, Germany). Mean choroidal volume in the study eye was 6.44 mm ( 1.6), and mean subfoveal choroidal thickness was 257.5 lm ( 72.3) at baseline. After injection of DEX 0.7, mean choroidal volume decreased significantly by 0.2 mm (95%CI: 0.31 to 0.1, p = 0.001) after 1 month, by 0.35 mm (95%CI: 0.56 to 0.15, p = 0.003) after 2 months and by 0.23 mm (95% CI: 0.41 to 0.05, p = 0.016) after 3 months (see Fig. 1). Similarly, subfoveal choroidal thickness decreased significantly after one month (MD 9.33 lm, 95%CI: 14.1 to 4.6, p = 0.001), after twomonths (MD 11.1 lm, 95%CI: 17.3 to 4.8, p = 0.003) and after three months (MD 19.6 lm, 95%CI: 36.5 to 2.6, p = 0.027). For the fellow eye, mean choroidal volume at baseline was 4.88 mm ( 0.75), and mean subfoveal choroidal thickness was 190.6 lm ( 34.2). No significant changes in mean choroidal volume and subfoveal choroidal thickness were observed during follow-up. This is, to the best of our knowledge, the first study to show a significant decrease in choroidal volume after DEX 0.7 injection in eyes with DME. The decrease in choroidal volume observed in this study suggests a global effect on the choroid. Choroidal volume is known to increase among other reasons due to inflammation, vasodilation and intersitital oedema (Zhang et al. 2014). As glucocorticoids are known to be anti-inflammatory, enhance vascular reactivity to vasoconstrictors and are antiexudative, a decrease in choroidal