The role of optical coherence tomography angiography in neovascular age related macular degeneration

Purpose: The aim of this study was to evaluate the relationship between spectral domain optical coherence tomography (SD-OCT) and fluorescein angiography (FA) findings and spectral domain optical coherence tomography angiography (SD-OCTA) findings in the diagnosis, follow-up and early treatment effects of patients with neovascular age related macular degeneration (nAMD) and demonstrate the applicability of SD-OCTA in the diagnosis and follow-up. Method: Treatment-naive patients who were diagnosed with nAMD in our clinic between April 2018 and November 2018 were included in the study, prospectively. Age, sex, visual acuity, intraocular pressure, anterior segment and fundus examination findings and anti-vascular endothelial growth factor (VEGF) medication were recorded. Spectral domain optical coherence tomography, FA and SD-OCTA [3x3 mm, 6x6 mm high definition (HD), en-face] scans were obtained before anti-VEGF injection and at first month after 3 loading dose. The main outome measures were greatest linear dimension (GLD) and maximum retinal pigment epithelial detachment (PED) height obtained by SD-OCT, membrane area and flow area obtained by SD-OCTA. The membrane area in early phase of FA was measured in type 2 choroidal neovascularization (CNV). Results: Sixty-seven eyes of 36 patients with treatment-naive CNV were included. The lesions were classified to SD-OCT and 33 eyes (89.19%) were recorded as type 1 CNV, 4 eyes (10.81%) were recorded as type 2 CNV. After anti-VEGF therapy, at SD-OCTA 3x3 mm angiogram, the mean membrane area regression was 0.72±1.05 mm2 (31.45±63.29%), the mean flow area regression was 0.28±0.43 mm2 (24.99±66.24%) (p<0,001). Correspondingly, at SD-OCTA 6x6 mm angiogram, the mean membrane area regression was 1.23±1.98 mm2 (50.14±34.36%), the mean flow area regression was 0.51±0.63 mm2 (47.80±33.16%) (p<0.001). We compared regression of membrane area and regression of flow area in SD-OCTA 3x3 mm and SD-OCTA 6x6 mm anjiograms. The correlations were found statistically significant (respectively; r=0.646, p<0.001, r=0.557, p<0.001). There were no statistically significant correlation between changes in SD-OCTA measurements (membrane area and flow area) and changes in SD-OCT measurements (GLD and PED). Conclusion: Diagnosis and follow-up of CNVs is possible with spectral domain optical coherence tomography angiography. It is thought that 6x6 mm HD SD-OCTA imaging is more appropriate in the presence of large CNVs. The limitations of optical coherence tomography angiography are still very important, but with the further development of this new technology, it is thought that its place in current practice will increase. Keywords: Age related macular degeneration, choroidal neovascularization, optical coherence tomography angiography