Background: Optical coherence tomography angiography allows an exact visualization of retinal vascular changes. To interpret the possibilities and limitations using OCTA in clinical practice, we analysed the quality of OCTA findings concerning the evaluability. Furthermore, we correlated our OCTA findings with fluorescein angiography (FAG) in relation of the presence of microaneurysms (MA) and enlargement of the foveal avascular zone (FAZ) in diabetic maculopathy.
Patients and methods: 30 eyes from 15 patients with diabetic maculopathy were imaged in 3 × 3mm volume scans and were depicted in OCTA mode (SSADA algorithm). By using the automatic segmentation we analysed the vascular changes in the superficial and deep capillary plexus and classified them concerning their qualitative evaluability. We analysed the number of MA in OCTA and fluorescein angiography and correlated them using an overlay technique. We analysed the presence of MA in the superficial and deep capillary plexus in OCTA as well. Furthermore we measured the enlargement of the foveal zone with both methods.
Results: In a large number of eyes we could not identifiy MA or measure the enlargement of the FAZ because of poor OCTA or FA quality. In the morphological analysis of our findings we identified a comparable number of MA in both methods, although the localization of the MA was different in both methods in a large number of eyes. The majority of MA was located in the deep capillary plexus. The extension of the foveal avascular zone measured in FA revealed a good correlation to the automatically measured "nonflow area" in the OCTA.
Conclusion: OCTA allows a good visualization of characteristic vascular changes in diabetic maculopathy. In spite of technical limitations OCTA generates a three-dimensional visualisation of avascular changes. The majority of microaneurysms detected by OCTA showed a corresponding finding in FA. The central avascular zone (FAZ) in OCTA correlates well with the findings from FA. OCTA represents an important additional diagnostic tool to interpret vascular changes in DM.
Keywords: Diabetic maculopathy; Fluorescein angiography; Foveal avascular zone; Microaneurysms; OCT angiography.