Optical Coherence Tomography Angiography in Diabetic Maculopathy

Abstract

Fluorescein angiography (FA) and indocyanine green angiography have provided information about the normal retinal and choroidal anatomy, nearly comparable to histological findings. These tests have been fundamental in the evaluation of all retinal and choroidal vascular diseases and have allowed clinicians to define and diagnose several pathological conditions. FA became the "gold standard" in retinal imaging due to the capacity to visualize the retinal capillary bed and its changes, both in the macular area and in the periphery. Although the fluorescence of the injected dye enabled improved visualization of retinal capillaries, not all the different layers of the retinal capillary network could be visualized in this bi-dimensional examination, mainly because of the light scattering phenomenon. By calculating the difference between static and non-static tissues, optical coherence tomography angiography (OCT-A) allows a depth-resolved visualization of the retinal and choroidal microvasculature. Given that the main moving elements in the ocular fundus are contained in blood vessels, determining a vascular decorrelation signal enables visualization of the 3-dimensional retinal and choroidal vascular networks without the intravenous dye injection, reducing therefore the risk of potential adverse events. Since OCT-A is perfectly co-registered with its structural OCT, both morphological findings, such as macular edema, and functional ones, like capillary drop-out, may be clearly evaluated on a single dye-free examination. Proficient detection of the different findings in diabetic maculopathy on OCT-A can result in a rapid analysis of the examination, and in the capacity to distinguish truly decorrelated structures (perfused vessels) from artifacts. Moreover, a complete morpho-functional assessment may help in determining both the origin and the clinical activity of a given vascular disease.

<p>Correlations Between Optical Coherence Tomography Angiography Parameters and the Visual Acuity in Patients with Diabetic Retinopathy</p>

“…that DR severity and BCVA were significantly correlated with SCP-VD rather than DCP-VD. [27][28][29][30][31][32][33][34][35][36] We found a significant negative correlation between the BCVA (LogMAR) and vessel density in both DCP and SCP. Our results are comparable to a study by Samara et al; 25 however, no correlation was found between them in another study.…”

“…Macular ischemia (inadequate blood supply) may contribute to both macular dysfunction and poor visual acuity. 4 Past studies concluded that diminished vessel density, irregularity of the FAZ and increased FAZ area were associated with progression and worsening of DR. 24,31,32 Other studies also reported that poorer visual acuity was correlated with diminished vessel density and widening of the FAZ area in DR patients without diabetic macular edema. 25 In a 2019 study, Hsiao et al 15 concluded that poor visual acuity in diabetic maculopathy was significantly correlated with decreased DCP-VD, and no correlation was found with SCP-VD.…”

An update on optical coherence tomography angiography in diabetic retinopathy

“…Introducing OCTA as an alternative imaging modality may alleviate the need for FA in many cases. [ 5 91 92 ]…”

Changes in Retinal and Choroidal Vascular Blood Flow after Oral Sildenafil: An Optical Coherence Tomography Angiography Study

“…Optical coherence tomography angiography is a novel diagnostic tool that can potentially impact ocular medical therapies in the future. It has been tried as an early diagnostic and assessment tool for age-related macular degeneration (AMD) [ 21 – 24 ], as a research tool in order to improve the current understanding of ischemic diseases that affects the different layers of the retinal microcirculation (diabetic retinopathy) [ 25 , 26 ], cotton wool spots, acute macular neuroretinopathy, paracentral acute middle maculopathy, and macular telangiectasia type 2 among others [ 27 – 29 ].…”