Detection of Microvascular Changes in Eyes of Patients With Diabetes but Not Clinical Diabetic Retinopathy Using Optical Coherence Tomography Angiography

Abstract

Optical coherence tomography angiography was able to image foveal microvascular changes that were not detected by clinical examination in diabetic eyes. Changes to the foveal avascular zone and capillary nonperfusion were more prevalent in diabetic eyes, whereas vessel tortuosity was observed with a similar frequency in normal and diabetic eyes. Optical coherence tomography angiography may be able to detect diabetic eyes at risk of developing retinopathy and to screen for diabetes quickly and noninvasively before the systemic diagnosis is made.

Optical coherence tomography angiography — novel method to access retinal microcirculation in patients with diabetic retinopathy

“…The reason for this discrepancy may be the low blood flow through the microaneurysms or flow of the serum without morphotic elements, which makes detecting them with decorelation method impossible. Numbers of microanerusyms lower than expected while using OCTA examinations were also reported by other authors [6,8,9].…”

“…Obtained images present an uncanny quality in mapping the smallest capillary network surrounding the macula, which enables a visualization of minimal structural abnormalities [6,8]. This could potentially lead to diagnosing vascular changes in diabetic patients much earlier than it is currently possible, but would also require performing OCTA on a large group of patients [9]. Another formidable advantage of OCTA when compared to FA is the ability to obtain images from various layers of the retina.…”

Can Foveal Avascular Zone (FAZ) Assessment By OCT Angiography, Used For Grading Of Diabetic Retinopathy?

“…Our center reviewed literature regarding the OCTA applications in diabetics which is going to be published soon. Available reports are few, but interesting facts regarding the FAZ is published [7][8][9][10][11][12][13][14][15][16][17][18]. The FAZ in normal individual was described in the OCTA as an intact well-demarcated round or oval area of reduced capillary density with a border without gaps, holes or interruption of the capillary network in both superficial and deep plexuses.…”

“…This finding may also add to our knowledge regarding pathophysiology behind the ischemic changes in DR. The OCTA has increased feasibility of qualitative FAZ assessment; but the most impressing are regarding the quantitative FAZ assessments the FAZ size increased significantly by progression of retinopathy grade in almost all reports [9][10][11][12][13][14][15][16][17]. (Table 1) has summarized current available range of the mean FAZ size values in different grades of disease.…”

“…For further details, one may refer to references or wait for our review article to be published. Furthermore, the FAZ is enlarged in diabetics not only before developing to apparent DR but even before systemic diagnosis of DM, so it could also be used as a predictor for whom may need closer follow up [11,15]. Putting these findings alongside our previous knowledge regarding the FAZ characteristics such as being considered as a vascular index and correlated to presumed ischemic pathophysiology behind DR; being correlated with VA in DR [9,19]; being able to help treatment selection as DME patients with larger FAZ was reported to be non-responder to laser therapy, who may benefit more from Anti-VEGF treatments [20]; being influenced by treatment modalities (laser or Anti-VEGF therapies) that may lead to reperfusion and reduce the FAZ area [17]; these altogether propose the FAZ characteristics as a potential qualitative and quantitative index that not only can be used to grade the DR but also to predict DR, guide the selection of appropriate treatment, help to localize laser treatment targets and follow up the effect of treatment.…”