Retinal imaging

Alessandro Papayannis MD, PhD, of the Manchester Vision Regeneration Lab, UK (Director: Prof P. E. Stanga), presented the results of his evaluation 
of the Topcon ultra wide-field swept-source optical coherence tomography-angiography (UWF SS OCT-A) in 86 eyes with diabetic retinopathy (DR) at the 16th EURETINA Congress in Copenhagen, Denmark. These images were then compared with those made using Optos California ultra wide-field colour fundus photography (UWF CFPh). Where clinically necessary, fundus fluorescein angiography (FFA) was performed. The purpose of the study was to describe the UWF SS OCT-A features of DR, using the CFPh or the FFA as a reference. Multiple SS OCT-A images were montaged to create an UWF SS OCT-A image. Two independent reviewers then compared the images as follows: 45-degree colour photography versus UWF SS OCT-A; UWF colour photography versus UWF SS OCT-A; and UWF FFA versus UWF SS OCT-A. “Across the 86 examined eyes, typical signs of DR, including macular oedema, retinal non-perfusion, neovascularisation of the disc and neovascularisation elsewhere were identified on UWF SS OCT-A with 100% reviewer agreement,” said Dr Papayannis. Of the 86 eyes examined, 36 underwent FFA. In 36 of 36 eyes, an enlarged foveal avascular zone and peripheral ischaemia were identified on both UWF FFA and UWF SS OCT-A, he said. Furthermore, 12 patients received the diagnosis of proliferative DR based on the FFA images. “Within the central 100 degrees, there was good correlation between sensitivity of UWF SS OCT-A and UWF FFA in detecting neovascularisation of the disc in 5/5 eyes, and neovascularisation elsewhere in 9/10 eyes,” said Dr Papayannis. He concluded that UWF SS OCT-A already has the ability to detect neovascularisation elsewhere up to the limits of an Optos California UWF FFA when acquired in the primary position. “In fact, UWF SS OCT-A allows us to visualise ischaemic alterations above areas treated with panretinal laser photocoagulation,” said Dr Papayannis. He showed images in which ischaemia was visible in the superficial and deep OCT-A images, depths that are masked on FFA imaging. Ischaemic changes in the choriocapillaris were clearly visible. “UWF SS OCT-A is a sensitive, non-invasive imaging technique that can offer additional topographic information with a layer-by-layer analysis regarding the localisation and the morphology of the vascular lesions in DR, from the retinal vascular plexuses to the vitreous cavity and from the posterior pole up to the mid-periphery,” he concluded. Detection of neovascular and ischaemic abnormalities seems to be as accurate as FFA. Alessandro Papayannis: alexandrospapayannis@yahoo.it

Tags: imaging, retina