Retinal Nonperfusion Research Articles

Microvascular Changes in the Cystic Lesion of Branch Retinal Vein Occlusion Imaged by Swept-Source Optical Coherence Tomography Angiography

Introduction: This study aimed to describe the quantitative features of the microvasculature in the cystic lesions of branch retinal vein occlusion (BRVO). Methods: A total of 43 eyes with BRVO, treated with anti-vascular endothelial growth factor therapy, were analyzed. Using wide-field swept-source optical coherence tomography angiography (OCTA), en face OCT images were obtained by depth-integrated reflectivity of the retina, and vascular density (VD), vascular length (VL), vascular lacunarity, and fractal dimension (FD) were evaluated in a 12 × 12-mm area of retinal nonperfusion. Results: The mean area of affected lesions was 38.7 ± 19.8 mm², and cystic lesions were 8.5 ± 10.1 mm². VD, VL, and FD were significantly decreased in the cystic lesions compared to other affected lesions in the same eyes (p = 0.0010, p = 0.0001, and p = 0.0003, respectively) and in all eyes (p = 0.0281, p = 0.0050, and p < 0.0001, respectively). VD in cystic lesions within the vascular arcade (25 eyes) correlated with best-corrected visual acuity on OCTA (r = −0.433, and p = 0.0492). Conclusions: Vascular structure in the cystic lesions was unpreserved compared to the other lesions in BRVO. These findings may help in understanding the pathophysiology of retinal edema in BRVO.

RETINAL NONPERFUSION IN THE EARLY TREATMENT DIABETIC RETINOPATHY STUDY SEVEN FIELDS COMPARED WITH WIDEFIELD FLUORESCEIN ANGIOGRAPHY

In previous landmark studies on central retinal vein occlusion, retinal nonperfusion assessments were obtained using 7-field (7F) angiography. The widespread current use of widefield imaging allows better visualization of the peripheral retina and more comprehensive estimation of the total area of nonperfusion. The relationship between nonperfusion measurement of 7F and widefield angiography (WFA) in central retinal vein occlusion has not been studied. We aim to identify the correlation of retinal nonperfusion measured within the 7F and on WFA in eyes with central retinal vein occlusion. Retinal nonperfusion in participants with central retinal vein occlusion was determined using a 7F Early Treatment Diabetic Retinopathy Study template and the concentric rings method. A total of 153 eyes were included. Pearson correlation test showed a near-perfect positive, linear correlation between the nonperfusion found in the 7F and total retinal nonperfusion on WFA (0.985 95% CI [0.793, 0.999]) The regression line equation for nonperfusion on 7F and WFA was y = 37 + 3.2x. Eyes with 0 disk areas (DA), >0 DA to 10 DA and >10 DA of nonperfusion on 7-fields had on average 23 DA 95% CI (19.20, 27.06), 45 DA 95% CI (35.75, 55.18), and 115 DA 95% CI (88.89, 142.05) on widefield respectively. There is a positive and linear relationship between nonperfusion measured by 7F and WFA in central retinal vein occlusion with more than 3-times the amount of nonperfusion identified on WFA. Despite <10 DA no areas of nonperfusion on 7F, there is typically at least 35 DA of nonperfusion on WFA whereas eyes with >10 DA of nonperfusion on 7F had at least 88 DA on WFA.

Neovascular Glaucoma from Ocular Ischemic Syndrome Treated with Serial Monthly Intravitreal Bevacizumab and Panretinal Photocoagulation: A Case Report

Purpose To describe a case of open-angle neovascular glaucoma (NVG) secondary to ocular ischemic syndrome (OIS) treated with a planned series of 6 monthly anti-VEGF injections with interspersed panretinal photocoagulation (PRP) sessions. We term this treatment protocol the Salvaging Conventional Outflow Pathway in Neovascular Glaucoma (SCOPING) Protocol, and this is our (MQ and DS) standard of care for all NVG patients presenting with partially or completely open angles. Case A 66-year-old man's right eye had a visual acuity of 20/50, intraocular pressure (IOP) of 42 mmHg on 0 IOP-lowering medications, and neovascularization of the iris and angle with no peripheral anterior synechiae. Fundoscopy revealed midperipheral dot-blot hemorrhages without diabetic retinopathy or vein occlusion. Fluorescein angiography revealed peripheral retinal nonperfusion in both eyes. The patient was diagnosed with open-angle NVG secondary to OIS and treated with 6 serial monthly anti-VEGF injections interspersed with 4 PRP sessions, after which his anterior segment neovascularization regressed and IOP normalized on 0 medications. Ten weeks after the last injection, the anterior segment neovascularization and elevated IOP recurred, so he underwent 4 more monthly anti-VEGF injections and 4 PRP sessions, after which his anterior segment neovascularization regressed and his IOP normalized on 0 medications. However, 6 weeks after the last injection, the anterior segment neovascularization and elevated IOP again recurred, so he was resumed on a third course of lifetime monthly anti-VEGF injections, which may be continued in perpetuity. Conclusion The patient's NVG was quiescent while under the protection of serial anti-VEGF injections with interspersed PRP; however, the disease recurred each time injections were stopped. Therefore, in patients with open-angle NVG secondary to OIS, serial monthly anti-VEGF injections may be necessary combined with PRP to suppress underlying neovascular drive and regress anterior segment neovascularization, maintain physiologic IOP, and prevent synechial angle closure.

IRVAN syndrome: A retrospective review of 9 cases from Tunisia

To describe clinical features, relevant imaging findings, disease course, and response to treatment in 9 patients (18 eyes) with idiopathic retinal vasculitis, aneurysms, and neuroretinitis (IRVAN) syndrome. Retrospective review of the charts of nine patients (18 eyes) diagnosed with IRVAN syndrome at Fattouma Bourguiba University Hospital, Monastir, Tunisia, from January 1, 2011 to January 1, 2022. Nine patients were included with bilateral involvement in all cases. Mean initial best-corrected visual acuity (VA) was 20/32 (range, 20/1600-20/20). Clinical findings at presentation included vitreous cells (10 eyes, 55.6%), peripapillary exudates (12 eyes, 66.7%), partial or complete macular star (11 eyes, 61.1%), and vascular sheathing (11 eyes, 61.1%). Fluorescein angiography showed arteriolar aneurysms (18 eyes, 100%), areas of peripheral capillary non-perfusion (16 eyes, 88.9%), and retinal neovascularization (6 eyes, 33.3%). Optical coherence tomography showed macular edema in 5 eyes (27.8%). Optical coherence tomography angiography of the optic disc demonstrated papillary aneurysms in 4 eyes of 2 patients. Indocyanine green angiography showed retinal arteriolar aneurysmal dilatations in 4 eyes of 2 patients. Ten eyes (55.6%) had stage 2 disease, 6 eyes (33.3%) had stage 3, and 2 eyes (11.1%) had stage 1. Treatment modalities included peripheral photocoagulation (16 eyes, 88.9%), intravitreal bevacizumab (4 eyes, 22.2%), and intravitreal triamcinolone acetonide (1 eye, 5.6%). Mean final best-corrected VA was 20/32 (range, 20/600-20/20). Ocular complications included vitreous hemorrhage in 3 eyes (16.7%), branch retinal artery occlusion in 2 eyes (11.1%) and submacular fibrosis in 3 eyes (16.7%). IRVAN syndrome should be highly suspected in patients with peripapillary exudates associated with vascular sheathing and vitreous cells. Multimodal imaging confirms the diagnosis by showing retinal macroaneurysms. Early treatment of macular edema and/or peripheral retinal non-perfusion is mandatory to improve prognosis.

ASSESSMENT OF FLUORESCEIN ANGIOGRAPHY NONPERFUSION IN EYES WITH DIABETIC RETINOPATHY USING ULTRAWIDE FIELD RETINAL IMAGING.

Evaluate association of retinal nonperfusion (NP) on ultrawide field (UWF) fluorescein angiography (FA) with diabetic retinopathy (DR) severity and predominantly peripheral lesions (PPL). Multicenter observational study, 652 eyes (361 participants) having nonproliferative DR (NPDR) without center-involved diabetic macular edema in at least one eye. Baseline 200° UWF-color and UWF-FA images were graded by a central reading center for color-PPL and FA-PPL, respectively. UWF-FA was graded for NP index within concentric zones: posterior pole (<10 mm from fovea), midperiphery (10-15 mm), and far periphery (>15 mm). Baseline Early Treatment Diabetic Retinopathy Study DR severity was 31.7% no DR/mild NPDR, 24.1% moderate NPDR, 14.0% moderately severe NPDR, 25.6% severe/very severe NPDR, and 4.6% proliferative DR. Worse DR severity was associated with increased NP index overall (P = 0.002), in the posterior pole (P < 0.001), midperiphery (P < 0.001), and far periphery (P = 0.03). On average, 29.6% of imaged retinal NP was in the posterior pole, 33.7% in midperiphery, and 36.7% in far periphery. Increased NP index was associated with FA-PPL (P < 0.001) but not with color-PPL (P = 0.65). Approximately, 70% of NP in diabetic eyes is located outside the posterior pole. Increased NP is associated with the presence of FA-PPL, suggesting UWF-FA may better predict future DR worsening than UWF-color alone.

Clinical significance of metabolic quantification for retinal nonperfusion in diabetic retinopathy

Diabetic retinopathy (DR) is characterized by microvascular changes including ischemia. Degradation and metabolic changes of various retinal cells occur during ischemia. Ischemic region containing more cells will lead to greater metabolic impairment. We analyzed the non-perfusion region (NPR) by integrating histologic mapping with ultra-widefield fluorescein angiography (UWF FA) images. We also investigated the correlations of the weighted ischemic index (ISI) considering the regional distribution of retinal cells with cytokines, macular edema (ME), and neovascularization (NV). In this study, 32 patients with treatment-naïve DR and 21 age-matched control participants were included. The difference between the non-weighted and weighted ISI of NPR with leakage was greatest at the posterior region. The weighted ISI of NPR with leakage was correlated with MCP-1, IL-8, IL-6, PlGF, and VEGF-A levels, while the non-weighted ISI of NPR with leakage was correlated with IL-8 and IL-6 levels. The presence of baseline ME or NV in patients with DR was associated with the weighted ISI, with a stronger association when cones and rods were weighted. The weighted ISI reflecting both metabolic activity and cell distribution demonstrated a better correlation with clinical features and was more valuable in NPR with leakage than non-weighted ISI, which previous studies conventionally used.

Inflammatory cytokines and retinal nonperfusion area in quiescent proliferative diabetic retinopathy.

We sought to investigate the association between inflammatory cytokine levels and retinal capillary nonperfusion area in eyes with quiescent proliferative diabetic retinopathy (PDR). Samples of aqueous humor were collected from 67 eyes (n = 42 patients) with treatment-naïve PDR. Levels of interleukin (IL)-10, IL-1β, IL-6, IL-8, monocyte chemoattractant protein 1 (MCP-1), and tumor necrosis factor-α (TNF-α) were obtained using multiplex bead assay. Areas of capillary nonperfusion at the posterior pole and peripheral retina were measured via ultra-widefield fluorescein angiography and correlated with cytokine levels. The levels of IL-10, IL-6, IL-8, MCP-1, and TNF-α were positively correlated with the nonperfusion area of the peripheral retina (r = 0.298, 0.401, 0.265, 0.435, and 0.393; all P ≤ 0.030). There were positive correlations between IL and 10, IL-6, IL-8, MCP-1, and TNF-α (all R ≥ 0.247; all P ≤ 0.043). IL-1β did not show a significant correlation with the nonperfusion area (P = 0.972 for posterior pole and 0.392 for periphery) but was positively correlated with TNF-α (r = 0.334; P = 0.006). An increased level of inflammation was observed in PDR eyes with larger nonperfusion areas, which suggests inflammation as a possible target for suppressing PDR progression associated with nonperfusion.

Fluorescein Angiography Detection of Combined Branch Retinal Vein and Artery Occlusion.

A77-year-old male with a history of diabetes mellitus, hypertension, chronic kidney disease, and hyperlipidemia presented for 1-month postoperative care following cataract extraction with a subjective complaint of a dark area in his left eye superior field. His uncorrected visual acuity measured 20/25 in each eye. The posterior ophthalmoscopic examination of the left eye revealed a large calcific embolus in the inferior retinal artery exiting the optic nerve (Fig. 1). The presence of moderate retinal hemorrhages consistent with diabetic and hypertensive retinopathy was evident.Figure 1: Color photograph showing large calcific embolus of the inferior retinal artery exiting the optic nerve.The fluorescein angiography study showed delayed filling of the inferior retinal artery in the arterial phase due to obstruction from an embolic vaso-occlusive event. The patient reported branch retinal artery occlusion symptoms, yet there were no acute ophthalmoscopic signs of venous occlusion. The collateral vein occlusion resulted from the proximity ofmechanical compression at the point of the shared arterial-venous adventitial sheath by the large embolus1 and was evident from the absent fluorescein filling within the inferior venous tributary (Fig. 2). Fluorescein angiography was of great diagnostic value to detect retinal non-perfusion from the combined branch retinal artery and vein occlusions, since the latter may have otherwise gone undiagnosed.Figure 2: Fluorescein angiography showing impaired inferior arterial filling and absent intermediate phase inferior venous circulation from embolic compression.

Optical Coherence Tomography with Angiography in the Diagnosis of Changes in the Organ of Vision at Atherosclerosis

Background. The study of the parameters of optical coherence tomography with angiography (OCTA) broadens the understanding of the state of hemodynamics for the early detection of vascular disorders of the organ of vision in atherosclerosis (AS).Purpose. To study the parameters of OCTA with changes in the organ of vision against the background of AS.Patients and methods. 26 patients (41 eyes) with changes in the organ of vision in AS. The age contingent of patients ranged from 32 to 78 years, the average age was 47.5 ± 2.0 year, of which 10 were women, 16 men. Depending on the damage to target organs, all patients were conditionally divided into 2 groups: group I (19 eyes) included patients without damage, and group II (22 eyes) consisted of patients with target organs damage.Results. The registration of OCTA in patients of group I, a decrease in the density of capillaries of the superficial vascular network was 15 % and amounted to 45.21 ± 2.62 % (p &lt; 0.05), of the deep vascular plexus by 19 %, which amounted to 45.89 ± 2, 71 % (p &lt; 0.05). In the macular region, the area of the hypoperfused retina was 1.07 ± 0.14 mm2 (p &lt; 0.05). In the region of the optic nerve disc, areas of hypoperfusion were noted in the superficial layers in 7 eyes and in the deep layers in 4 eyes. Analysis of OCTA in patients of group II revealed a sharp decrease (by 48 %) in the density of capillaries in both the superficial and deep vascular plexuses of the retina, which amounted to 33.91 ± 3.01 % (p &lt; 0.05); 33.65 ± 2.89 % (p &lt; 0.05), respectively. In the macular region, the area of the non-perfused retina was 2.19 ± 0.21 mm2 (p &lt; 0.05). In the area of the optic nerve disc, areas of nonperfusion were noted both in the surface layers and in the deep layers in 4 eyes.Conclusion. The use of OCTA allows to detect changes in hemoperfusion in all layers of the retina and optic nerve in the early stages of AS development, which will allow early diagnosis and monitoring of the disease.

Исследование частоты развития транзиторной ретинопатии у беременных женщин, страдающих сахарным диабетом

Purpose. Assessment of the incidence progression of transient retinopathy (TR) in pregnant women with diabetes mellitus (DM). Material and methods. 24 pregnant women with DM were examined in each trimester of pregnancy and 3 months after delivery. In 10 pregnant women, diabetic retinopathy (DR) was not detected, in 14 (58 %) DR was diagnosed. With the progression of DR panretinal photocoagulation (PRP) was performed. Results. Progression of DR during pregnancy was observed in 9 (64 %) patients with preproliferative and proliferative DR and uncompensated glycemia, macular edema (ME) developed in both eyes in 3 patients. According to optical coherence tomography angiography (OCT-A), in all these patients, a progressive expansion of retinal nonperfusion zones in the superficial or deep plexus during pregnancy was detected. In all patients with progression of DR, the symptoms of retinopathy persisted in the postpartum period. “Transient” was focal macular edema in one patient with preproliferative DR, which regressed after delivery. Conclusions. 1. DR, detected at the beginning of pregnancy, progressed in 64% of pregnant women against the background of glycemic status decompensation. 2. TR occurred in one case and was manifested by transient macular edema. 3. According to our data, DR manifesting during pregnancy is most often true. 4. Identification of non-perfusion zones in the superficial and deep retinal plexus using the OCT-A allows differential diagnosis of DR and TR in pregnant women with DM. Keywords: transient retinopathy, diabetic retinopathy, pregnancy, optical coherence tomography angiography.

Study of Nonperfusion Area Changes after Ranibizumab Intravitreal Injection for Diabetic Macular Edema by Means of Widefield OCT Angiography

Introduction: The aim of this study was to evaluate changes in retinal capillary nonperfusion areas (RCNPA) and the retinal capillary vessel density (RCVD) of the superficial capillary plexus (SCP) and deep capillary plexus (DCP) using widefield optical coherence tomography angiography (WFOCTA) in patients with diabetic retinopathy (DR) and diabetic macular edema (DME) treated with intravitreal ranibizumab injection (IRI). Materials and Methods: Twenty-four eyes of 24 patients with DR and DME candidates to a loading dose of IRI were enrolled. All patients underwent WFOCTA with the PLEX Elite 9000 device with 15 × 9 mm scans centered on the foveal center at baseline (T0) and 1 month after each intravitreal injection at 30 days (T1), 60 days (T2), and 90 days (T3). In all patients, the variation of RCNPA and the RCVD of the SCP and DCP were calculated using automatic software written in MATLAB (MathWorks, Natick, MA, USA). Results: The SCP showed a significant longitudinal variation of RCNPA (p = 0.04). Post hoc analysis revealed a statistically significant reduction of RCNPA at T1 (p = 0.04) and a nonsignificant reduction at T2 (p = 0.18) and T3 (p = 0.96). The DCP showed longitudinal changes in the RCNPA that tended to statistical significance (p = 0.09). Post hoc analysis revealed a trend toward a statistically significant reduction of RCNPA at T3 (p = 0.09) not statistically significant at T1 (p = 0.17) and T2 (p = 0.75). The RCVD of SCP and DCP showed no significant changes at any of the time points. Conclusions: WFOCTA showed a decrease in RCNPA after IRI, probably related to the reperfusion of retinal capillaries.

Final Outcomes from the Randomized RECOVERY Trial of Aflibercept for Retinal Nonperfusion in Proliferative Diabetic Retinopathy

Retinal nonperfusion (RNP) is an important biomarker for diabetic retinopathy (DR). Data suggest that consistent anti-VEGF pharmacotherapy can slow RNP development. The RECOVERY trial evaluated the impact of aflibercept (Eylea, Regeneron) on RNP among eyes with proliferative DR (PDR). Prospective, randomized clinical trial with treatment crossover in the second year. Eyes with PDR and RNP. At baseline, the subjects were randomized 1:1 to monthly (arm 1) or quarterly (arm 2) intravitreal 2 mg aflibercept. At the beginning of year 2, the treatment arms were crossed over so that the monthly-dosed subjects subsequently received quarterly dosing and the quarterly-dosed subjects subsequently received monthly dosing. Change in total RNP area (mm2) through year 2. Secondary outcomes included Diabetic Retinopathy Severity Scale (DRSS) scores; best-corrected visual acuity; central subfield thickness; additional measures of RNP, including ischemic index (ISI); and adverse event incidence. Means and 95% confidence intervals were calculated. Among all subjects, from baseline to year 2, the mean RNP increased from 235 mm2 to 402 mm2 (P < 0.0001), and the ISI increased from 25.8% to 50.4% (P < 0.0001). Increases in the mean RNP (P < 0.0001) and ISI (P < 0.0001) were also observed from year 1 to year 2. The mean total RNP increased from 264 mm2 at baseline to 386 mm2 (P < 0.0001) at year 2 in arm 1 and from 207 mm2 at baseline to 421 mm2 (P < 0.0001) at year 2 in arm 2 (P= 0.023, arm 1 vs. arm 2). Increases in the mean RNP for both treatment arms (P < 0.0001) were also specifically observed within year 2 (P= 0.32, arm 1 vs. arm 2). Compared with baseline, the DRSS scores at the end of year 2 improved in 82% (n= 27) of subjects and remained stable in 18% (n= 6), with no subjects experiencing worsening; at 2 years, the DRSS scores had improved by 2 or more steps in 65% (n= 11) and 81% (n= 13) of subjects in arms 1 and 2, respectively. Through year 2 of the RECOVERY trial, both treatment arms experienced significant increases in RNP. Despite the expansion of the RNP area in nearly all subjects, 82% of subjects demonstrated an improvement in DRSS levels from baseline, with no subjects experiencing worsening in DRSS scores.

Optical Coherence Tomography Angiography in Central Retinal Vein Occlusion: Macular Changes and Their Correlation with Peripheral Nonperfusion at Ultra-Widefield Fluorescein Angiography

Introduction: The aim of this study was to investigate the correlation between ischemic index (ISI) measured on ultra-widefield (UWF) fluorescein angiography (FA) images and macular parameters obtained by optical coherence tomography angiography (OCT-A) in eyes affected by central retinal vein occlusion (CRVO). Methods: Retrospective study of data from 12 eyes affected by treatment-naïve CRVO. All patients underwent a comprehensive ocular examination including structural OCT, OCT-A, and UWF FA. Variables analyzed included best corrected visual acuity (BCVA) measured with the ETDRS chart; foveal avascular zone (FAZ) area at full-thickness OCT-A angiogram; perfusion density (PD) in the superficial (SCP) and deep capillary plexus (DCP); ISI; and central macular thickness (CMT). Results: ISI showed a significant positive correlation with FAZ area (r = 0.63, p = 0.019) and a significant negative correlation with PD in the SCP (r = −0.62, p = 0.022), PD in the DCP (r = −0.66, p = 0.011), and BCVA (r = −0.75, p = 0.002). FAZ area also negatively correlated to PD in the SCP (r = −0.75, p = 0.002) and DCP (r = −0.64, p = 0.016). BCVA positively correlated to PD in the SCP (r = 0.67, p = 0.009) and DCP (r = 0.68, p = 0.008), while a negative correlation was found with FAZ area (r = −0.65, p = 0.013) and CMT (r = −0.70, p = 0.006). Discussion/Conclusion: OCT-A macular parameters (namely, FAZ area and PD of SCP and DCP) significantly correlated with ISI, a quantitative way to assess peripheral retinal nonperfusion on UWF FA. Macular OCT-A analysis may help in assessing the need for additional UWF FA testing in eyes affected by CRVO.

Ischemic index and distribution of retinal capillary non-perfusion in neovascular glaucoma.

Neovascular Glaucoma (NVG) is a condition normally caused by hypoxic posterior ocular disease, which produces angiogenic factors such as vascular endothelial growth factor (VEGF) that stimulate new vessel proliferation of the anterior segment and angle, eventually leading to angle closure, reduced outflow of aqueous humor and increased intraocular pressure. Without treatment elevated intraocular pressure can rapidly progress to loss of vision. Treatment includes addressing the intraocular pressure and reducing the ischemic drive with panretinal photocoagulation (PRP) of the ischemic retina. Recent imaging advancements allow for ultra-widefield fluorescein angiography (UWFA) which expand the amount of peripheral retina that can be evaluated for non-perfusion. Here we aim to study patterns of non-perfusion in NVG using a group of PRP naïve patients with recent onset NVG. This study is a retrospective single-center cross-sectional study of patients seen at LAC + USC Medical Center from January 2015 to April 2020 with new onset NVG, without PRP and with UWFA completed. The percentage of ischemic index of the retina was calculated from the UWFA and evaluated in three distinct zones centered on the fovea: the posterior pole, the mid periphery, and far periphery. To increase sample size, a confirmatory group was included, with PRP allowed prior to UWFA but not before diagnosis. In addition, the time between diagnosis and UWFA was increased to 6 months. A total of 11 eyes met inclusion criteria for the primary group. Ischemic index was found to be 91% in the far periphery, 77% in the mid periphery, and 42% at the posterior pole. The total average ischemic index was 76%. There was a statistically significant difference between the far periphery and posterior pole and mid periphery and posterior pole. A total of 24 eyes met criteria for the confirmatory group. Ischemic index for the confirmatory group was found to be 93% in the far periphery, 75% in the mid periphery, and 35% at the posterior pole. There was a statistically significant difference between the far periphery, posterior pole and mid-periphery. This knowledge can be used to further guide treatment and understand risk for NVG.

Retinal non-perfusion in diabetic retinopathy.

Diabetic retinopathy is a major cause of vision loss worldwide and areas of retinal non-perfusion (RNP) are a key pathologic feature of the vascular component of diabetic retinopathy. While there is a need for a more complete understanding of the natural history of RNP development and progression, overall, increasing RNP has been closely linked with worsening DR severity. Both traditional and novel approaches to quantitative image assessment are being explored to advance our understanding of the vascular, physiologic and functional changes associated with progressive RNP. Retinal ischemia secondary to RNP leads to tissue hypoxia and changes in the expression of a host of signalling molecules. Current anti-vascular endothelial growth factor and steroid pharmaceutical agents appear to be unable to reperuse areas of RNP, but may be able to slow the progressive longitudinal accumulation of RNP with regular retreatments. There remains a tremendous unmet need for pharmacotherapies that can slow RNP progression and ultimately reperfuse areas of the non-perfused retina. Towards this end, novel targets including the semaphorin family are being investigated.

Effect of anti-VEGF treatment on nonperfusion areas in ischemic retinopathy.

In recent years, retinal ischemia such as that which occurs in diabetic retinopathy (DR) and retinal vein occlusion (RVO) has become a hotspot of ischemic retinopathy research. High levels of vascular endothelial growth factor (VEGF) are recognized as a major cause of macular edema (ME) in DR and RVO. High concentrations of VEGF in the vitreous can lead to serious retinal ischemia and hypoxia and form retinal nonperfusion areas (NPAs). Different levels of retinal ischemia can represent disease severity and progression. Anti-VEGF therapy as the first-line treatment for ME has been found to be effective in improving vision, but there are still disputes about whether anti-VEGF therapy could improve retinal ischemia and achieve reperfusion of previously developed retinal NPAs. Here, we review and summarize studies of the effects of anti-VEGF drugs on retinal ischemia, especially NPAs.

Update on Optical Coherence Tomography and Optical Coherence Tomography Angiography Imaging in Proliferative Diabetic Retinopathy.

Proliferative diabetic retinopathy (PDR) is a major cause of blindness in diabetic individuals. Optical coherence tomography (OCT) and OCT-angiography (OCTA) are noninvasive imaging techniques useful for the diagnosis and assessment of PDR. We aim to review several recent developments using OCT and discuss their present and potential future applications in the clinical setting. An electronic database search was performed so as to include all studies assessing OCT and/or OCTA findings in PDR patients published from 1 January 2020 to 31 May 2021. Thirty studies were included, and the most recently published data essentially focused on the higher detection rate of neovascularization obtained with widefield-OCT and/or OCTA (WF-OCT/OCTA) and on the increasing quality of retinal imaging with quality levels non-inferior to widefield-fluorescein angiography (WF-FA). There were also significant developments in the study of retinal nonperfusion areas (NPAs) using these techniques and research on the impact of PDR treatment on NPAs and on vascular density. It is becoming increasingly clear that it is critical to use adequate imaging protocols focused on optimized segmentation and maximized imaged retinal area, with ongoing technological development through artificial intelligence and deep learning. These latest findings emphasize the growing applicability and role of noninvasive imaging in managing PDR with the added benefit of avoiding the repetition of invasive conventional FA.

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Disentangling the association between retinal non-perfusion and anti-VEGF agents in diabetic retinopathy.

Diabetic retinopathy (DR) is the most common microvascular complication of diabetes mellitus (DM) and the leading cause of blindness in patients with DM. In the pathogenesis of DR, chronic hyperglycemia leads to biochemical and structural alterations in retinal blood vessels' wall, resulting in hyperpermeability and non-perfusion. Since vascular endothelial growth factor (VEGF) has been found to play a significant role in the pathogenesis of DR, this review sheds light on the effect of intravitreal anti-VEGF agents on retinal non-perfusion in patients with DR. Based on the existing literature, anti-VEGF agents have been shown to improve DR severity, although they cannot reverse retinal ischemia. The results of the published studies are controversial and differ based on the location of retinal non-perfusion, as well as the imaging modality used to assess retinal non-perfusion. In cases of macular non-perfusion, most of studies showed no change in both fundus fluorescein angiography (FFA) and optical coherence tomography (OCTA) in patients with DR treated with intravitreal anti-VEGF agents, while few studies reported worsening of non-perfusion with enlargement of foveal avascular zone (FAZ). Regarding peripheral ischemia, studies using wide-field-FFA demonstrated an improvement or stability in non-perfusion areas after anti-VEGF treatment. However, the use of wide-field-OCTA revealed no signs of re-perfusion of retinal vessels post anti-VEGF treatment. Further prospective studies with long follow-up and large sample size are still needed to draw solid conclusions.

Intravitreal Anti-Vascular Endothelial Growth Factor Agents for the Treatment of Diabetic Retinopathy: A Review of the Literature.

Background: Diabetic retinopathy (DR) is the leading cause of blindness in the working-age population. The purpose of this review is to gather the existing literature regarding the use of the approved anti-vascular endothelial growth (anti-VEGF) agents in the treatment of DR. Methods: A comprehensive literature review in PubMed engine search was performed for articles written in English language up to 1 July 2021, using the keywords “diabetic retinopathy”, “ranibizumab”, “aflibercept”, and “anti-VEGF”. Emphasis was given on pivotal trials and recent robust studies. Results: Intravitreal anti-VEGF agents have been found to significantly improve visual acuity and reduce retinal thickness in patients with diabetic macular edema (DME) in a long-term follow-up ranging from 1 to 5 years and are considered the standard-of-care in such patients. Regarding DR, intravitreal anti-VEGF agents provided ≥2-step improvement in DR severity on color fundus photography in about 30–35% of patients with NPDR at baseline, in the majority of clinical trials originally designed to evaluate the efficacy of intravitreal anti-VEGF agents in patients with DME. Protocol S and CLARITY study have firstly reported that intravitreal anti-VEGF agents are non-inferior to panretinal photocoagulation (PRP) in patients with proliferative DR (PDR). However, the use of new imaging modalities, such as optical coherence tomography-angiography and wide-field fluorescein angiography, reveals conflicting results about the impact of anti-VEGF agents on the regression of retinal non-perfusion in patients with DR. Furthermore, one should consider the high “loss to follow-up” rate and its devastating consequences especially in patients with PDR, when deciding to treat the latter with intravitreal anti-VEGF agents alone compared to PRP. In patients with PDR, combination of treatment of intravitreal anti-VEGF agents and PRP has been also supported. Moreover, in the specific case of vitreous hemorrhage or tractional retinal detachment as complications of PDR, intravitreal anti-VEGF agents have been found to be beneficial as an adjunct to pars plana vitrectomy (PPV), most commonly given 3–7 days before PPV, offering reduction in the recurrence of vitreous hemorrhage. Conclusions: There is no general consensus regarding the use of intravitreal anti-VEGF agents in patients with DR. Although anti-VEGF agents are the gold standard in the treatment of DME and seem to improve DR severity, challenges in their use exist and should be taken into account in the decision of treatment, based on an individualized approach.