Abstract
BackgroundDiabetic retinopathy (DR) is a leading cause of blindness due to diabetic macular edema (DME) or complications of proliferative diabetic retinopathy (PDR). Optical coherence tomography (OCT) is a noninvasive imaging technique well established for DME but less used to assess neovascularization in PDR. Developments in OCT imaging and the introduction of OCT angiography (OCTA) have shown significant potential in PDR.ObjectivesTo describe the tomographic features of PDR, namely of neovascularization, both of the optic disc (NVD) and elsewhere (NVE), intraretinal microvascular abnormalities (IRMA), retinal nonperfusion areas (NPA), status of the posterior vitreous, vitreoschisis and vitreous and subhyaloid/sub-ILM hemorrhages.Data sourcesElectronic database search on PubMed and EMBASE, last run on December 19th 2019.Study eligibility criteria, participants and interventionsPublications assessing OCT and/or OCTA findings in PDR patients. All study designs were allowed except for case-reports, conference proceedings and letters.Study appraisalNewcastle–Ottawa Scale for observational studies was used for purposes of risk of bias assessment.ResultsFrom the 1300 studies identified, 283 proceeded to full-text assessment and 60 were included in this comprehensive review. OCT was useful in detecting NVD and NVE, such as in characterizing disease activity and response to laser and/or anti-VEGF therapies. The absence of posterior vitreous detachment seemed determinant for neovascular growth, with the posterior hyaloid acting as a scaffold. OCTA allowed a more detailed characterization of the neovascular complexes, associated NPA and disease activity, allowing the quantification of neovessel area and flow index. However, changes in OCTA blood flow signal following local therapies did not necessarily correlate with structural regression. Widefield and ultra-widefield OCTA were highly sensitive in the detection of PDR, adding value to disease staging and monitoring. Compared to fluorescein angiography, OCTA was more sensitive in detecting microvascular changes indicating disease progression.LimitationsPublication languages were restricted. Most included studies were observational and non-comparative. Risk of bias regarding case representativeness.ConclusionsOCT-based retinal imaging technologies are advancing rapidly and the trend is to be noninvasive and wide-field. OCT has proven invaluable in diagnosing, staging and management of proliferative diabetic disease with daily application in clinical and surgical practices.
Highlights
Diabetic retinopathy (DR) is a leading cause of blindness due to diabetic macular edema (DME) or complications of proliferative diabetic retinopathy (PDR)
Optical coherence tomography (OCT) was useful in detecting NVD and Neovascu‐ larization elsewhere (NVE), such as in characterizing disease activity and response to laser and/or anti-Vascular endothelial growth factor (VEGF) therapies
The absence of posterior vitreous detachment seemed determinant for neovascu‐ lar growth, with the posterior hyaloid acting as a scaffold
Summary
Diabetic retinopathy (DR) is a leading cause of blindness due to diabetic macular edema (DME) or complications of proliferative diabetic retinopathy (PDR). Optical coherence tomography (OCT) is a noninvasive imaging technique well established for DME but less used to assess neovascularization in PDR. Optical coherence tomography (OCT) was first introduced in ophthalmology in 1996, becoming standard of care for macular disease in 2005 [13]. In 2014, commercial OCT angiography (OCTA) was introduced [13] and in the last years there has been a significant number of publications demonstrating proliferative diabetic changes [22,23,24,25,26,27,28], some even using widefield (WF) imaging [29,30,31,32]. Combining OCT with the surgical microscope aided in the immediate evaluation of vitreoretinal structures and in identifying surgical planes, helping in membrane delamination/segmentation, a crucial step in diabetic tractional retinal detachment (TRD) surgery [12, 33,34,35]
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