OCT angiography in adult primary rhegmatogenous retinal detachment before and after vitreoretinal surgery

Purpose : To analyze the morphological characteristics of adult primary rhegmatogenous retinal detachment ( RRD) assessed by optical coherence tomography angiography (OCT-A) before and after 25 gauge pars plana vitrectomy(25 G PPV), with gas or silicone oil tamponade. Methods : Retrospective review all RDD surgeries performed between june and october 2016 with anatomical success, defined as a complete retinal attachment,. All patients underwent a complete ophthalmological examination, including fundus photography, spectral-domain OCT ( Cirrus 5000 SD-OCT, Zeiss, Germany) and OCT-A (Optovue XR Avanti, Optovue, USA), before and at follow-up visits ranging from 1 month to 6 months after RRD surgery. OCT-A retinal capillary density flow analysis was performed at four main depth intervals: 1) the superficial capillary plexus, acquired with automatic segmentation , 2) the deep capillary plexus, 3) photoreceptors ,and 4)choriocapillaris , all acquired with manual segmentation. Statistical analysis was performed by means of Mann Whitney U test and Wilcoxon W test. Results : Fifty-one eyes of 51 patients were analyzed. Operative procedures included pars-plana vitrectomy 25 G, exchange BSS/PFCL , endolaser, and intraocular tamponade with 50% sulfur hexafluoride gas in 36 eyes, and silicone oil in 15 eyes. Forty-five eyes were macula off and six eyes were macula on. Before surgery, in macula-off patients we observed a marked reduction of capillary flow in superficial, deep and choriocapillary layers. After surgery, in macula-off patients, SD OCT demonstrated the presence of foveolar lucencies in 17% of cases, while OCT-A revealed enlargement and irregular changes of the foveal avascular zone ( FAZ ), and a residual significant hypoperfusion at the level of outer retina and photoreceptors. In macula-on patients, no lucencies were detected, and a subtle hypoperfusion of all retinal layers, less severe than in macula-off cases, was apparent at OCT-A. Conclusions : OCT-A is a noninvasive imaging modality that allows visualization of retinal capillary density flow changes occurring after surgery for retinal detachment, and it could represent a predictive tool of visual acuity and retinal sensitivity recovery after 25 G PPV with gas or silicone oil tamponade