Early effects of intravitreal steroid on severe diabetic macular edema: morphological and functional features

Purpose : To evaluate the early effects of intravitreal steroid therapy for diabetic macular edema (DME) on intraretinal structure and function. Methods : This prospective study included 12 eyes of 10 consecutive patients who underwent intravitreal injection of a slow release steroid implant (Ozurdex, Allergan, USA) for severe DME. We defined as severe DME a central retinal thickness (CRT) > 450mm, presenting intraretinal cysts, subretinal (SRF) and intraretinal fluid (IRF); fluorescein angiography was performed at baseline to complete the diagnosis and classification of retinal pathology. We included patients naïve and patients previously treated with antiVEGF (from more than 6 months). We excluded patients affected by tractional DME and edema secondary to other vascular and inflammatory diseases. Baseline and follow up evaluations included complete ophthalmological evaluation and instrumental examination. Follow up visit were performed at day 7, 14 and 30 and then at month 1, 2 and 3. Functional evaluation was performed by ETDRS visual acuity; morphological evaluation was performed by CRT and retinal layers analysis on B-scan with SD OCT (Topcon 3D-OCT, USA). Statistical analysis was performed on collected data. Results : Mean CRT decreased from 567,8 ± 120,6 mm at baseline to 242,4 ± 56,8 mm at month 3 (p<0.05). The SRF was the first pathological feature reducing on early follow up visits with a mean reduction of 109,6mm at month 1, followed by the reduction of IRF. The position and extension of intraretinal hard exudates changed with a migration within the foveal region and a deposition on outer retinal layers in 60% of patients. Mean visual acuity significantly increased from 1,06 ± 0,2LogMAR at baseline to 0,53 ± 0,1 LogMAR at month 3 (p<0.05). All patients reported a reduction in visual blurring, metamorphopsia and colour disturbancies. Conclusions : Steroid therapy demostrated its early effectiveness to reduce the effects of diabetic maculopathy on retinal morphology and function. At month 3 we showed significative results in function and morphology. Beware of the presence of hard exsudates that could influence a long-term results as they lay on foveal photoreceptor.