Utilisation of optical coherence tomography and optical coherence tomography angiography to assess retinal neovascularisation in diabetic retinopathy

Purpose To evaluate the use of optical coherence tomography angiography (OCTA), structural OCT and fundus fluorescein angiography (FFA) to distinguish neovascularisation elsewhere (NVE) from intra retinal microvascular abnormalities (IRMA) and their use in early detection and possible risk assessment for vitreous haemorrhage. Methods A cross-sectional study of a consecutive series of patients with suspected NVE and IRMA using clinical examination and FFA, were examined further with OCT and OCTA. Treated and untreated eyes were also compared. Results Images from 33 eyes of 26 patients, showed 27 NVE and 14 IRMA lesions based on clinical examination +/- FFA. Lesions were re-classified as NVE in 22 eyes. Ten eyes had received past treatment. In all 10 treated eyes, vascular flow and vitreous connection were found but not FFA leakage. In 18/22 eyes with NVE there was a breach of the internal limiting membrane (ILM), in 4 eyes there was FFA leak, ILM outpouching but no breach. In two eyes, NVE originated from sea fan IRMA. Ten eyes images were classified as IRMA only with no FFA leak, or ILM breach. The relation of pre-retinal NVE to the vitreous can be visualised. Conclusion Lesions, considered to be NVE, after further assessment with OCT and OCTA, can be intra-retinal, with ILM disruption but no ILM breach and leakage on FFA. ILM disruption maybe one of the earliest signs of the development of neovascularisation. Visualisation of the relation to the posterior vitreous is likely to be useful in assessing risk of vitreous haemorrhage.