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

Response of Diabetic Macular Edema to Anti-VEGF Medications Correlates with Improvement in Macular Vessel Architecture Measured with OCT Angiography

Purpose

Improvements in best-corrected visual acuity (BCVA) and central subfield thickness (CST) have been well documented after intravitreal injection of anti-VEGF medications in diabetic macular edema (DME); however, their effect on the vasculature of the macula in diabetic retinopathy (DR) remains poorly understood. Our aim was to explore the effect of intravitreal injection of anti-VEGF on parameters of retinal vascular microstructure in DR with OCT angiography (OCTA).

Design

Retrospective study of adult patients with DME that were treated with anti-VEGF intravitreal injections at the University of Illinois at Chicago between 2017 and 2022.

Participants

Forty-one eyes from 30 patients with nonproliferative or proliferative DR with a mean age of 58.83 ± 11.71 years, mean number of intravitreal injections of 2.8 ± 1.4, and mean follow-up of 6.5 ± 1.7 months.

Methods

ImageJ was employed to measure parameters of retinal vascular microstructure in OCTA images, which included perfusion density, vessel-length density (VLD), vessel diameter, and foveal avascular zone (FAZ) characteristics (area, perimeter, and circularity). Student t tests and analysis of variance were used to determine statistical significance.

Main Outcome Measures

A primary analysis was performed comparing the mean of each parameter of all patients as a single group at the beginning and end of the study period. A subgroup analysis was then performed after stratifying patients based on visual improvement, change in CST, prior injection history, and number of injections.

Results

Eyes demonstrated statistical improvement in BCVA logarithm of the minimum angle of resolution score and CST after anti-VEGF treatment. Primary analysis showed a reduction in the vessel diameter of the superficial and deep retinal vasculature, as well as an increase in the circularity of the FAZ within the superficial retinal vasculature after anti-VEGF treatment. Subgroup analysis revealed that eyes with improvement in BCVA exhibited reduced vessel diameter in the superficial retinal vasculature and that eyes with the largest decrease in CST displayed increased perfusion density and VLD in the deep retinal vasculature.

Conclusions

Intravitreal injection of anti-VEGF agents to treat DME improved parameters of retinal vascular microstructure on OCTA over a period of 3 to 9 months, and this effect was most pronounced in eyes that experienced improvement in BCVA and CST.

Financial Disclosures

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Central retinal vein occlusion in patients with metastatic solid tumors on tyrosine kinase inhibitors: a report of case series and literature review

Background

Central retinal vein occlusion (CRVO) is a rare adverse effect related to the use of tyrosine kinase inhibitors (TKIs) in patients with metastatic malignancies, which has only been reported in several case reports.

Case presentation

We reported the case series of three CRVO patients on regular regimens of TKIs as part of targeted therapies for metastatic malignancies, all of whom were otherwise healthy with no or well-controlled systemic conditions. All these patients received injections of intravitreal dexamethasone implant (IDI) and achieved a fluid-free macula at the end of the visit. In addition, we reviewed the existing literature on this subject and present here an updated analysis of the related TKIs, ocular presentation, treatment, and prognosis.

Conclusion

All patients diagnosed with CRVO on TKIs received dexamethasone implant treatment and obtained a fluid-free macula. We would like to raise awareness among our colleague oncologists about the possibility of CRVO related to TKI use and the necessity for patients to be screened regularly by a retinal specialist.

Aflibercept versus ranibizumab for diabetic macular edema: A meta-analysis

OBJECTIVE

The purpose of this study was to compare the efficacy and safety of aflibercept (AFL) versus ranibizumab (RAN) for the treatment of diabetic macular edema (DME).

METHODS

The PubMed, Embase, Cochrane Library, and CNKI databases were searched up to September 2022 to identify prospective randomized controlled trials (RCTs) comparing AFL with RAN for the treatment of DME. Review Manager 5.3 software was used for data analysis. We used the GRADE system to evaluate the quality of the evidence for each outcome.

RESULTS

A total of 8 RCTs involving 1067 eyes (939 patients) were included; there were 526 eyes in the AFL group and 541 eyes in the RAN group. Meta-analysis revealed that there was no significant difference between RAN and AFL in the best-corrected visual acuity (BCVA) of DME patients at 6 months (WMD: -0.05, 95% CI  =  -0.12 to 0.01, moderate quality) and 12 months after injection (WMD: -0.02, 95% CI  =  -0.07 to 0.03, moderate quality). Additionally, there was no significant difference between RAN and AFL in the reduction of central macular thickness (CMT) at 6 months (WMD: -0.36, 95% CI  =  -24.99 to 24.26, very low quality) and 12 months after injection (WMD: -6.36, 95% CI  =  -16.30 to 3.59, low quality). Meta-analysis showed that the number of intravitreal injections (IVIs) for AFL was significantly lower than that for RAN (WMD: -0.47, 95% CI  =  -0.88 to -0.05, very low quality). There were fewer adverse reactions to AFL than to RAN, but the difference was not significant.

CONCLUSION

This study found that there was no difference in BCVA, CMT or adverse reactions between AFL and RAN at 6 and 12 months of follow-up, but AFL needed fewer IVIs than RAN.

Corneal Sensitivity Is Inversely Correlated With Severity of Diabetic Retinopathy in a Predominantly Underrepresented Population

PURPOSE

To assess the relationship between diabetic retinopathy (DR) and corneal sensitivity.

METHODS

In this prospective study, 100 eyes of 50 patients from primarily underrepresented racial and ethnic backgrounds with DR underwent assessment of corneal sensitivity using a Cochet-Bonnet esthesiometer. Severity of DR was graded by a masked reading center. Corneal sensitivity was compared in eyes with current or regressed proliferative DR (PDR) (n=35) and eyes with nonproliferative DR (NPDR) with no history of PDR (n=65). Corneal sensitivity in eyes that regressed from PDR to NPDR with anti-vascular endothelial growth factor (anti-VEGF) therapy (n=7) was compared to treatment-naïve eyes with no current or prior PDR (n=55) and to eyes with newly diagnosed, treatment-naïve PDR (n=12).

RESULTS

In eyes with current or prior PDR, the median corneal sensitivity (average of 4 quadrants) was 0.5 cm (interquartile range [IQR] 0-3.375), whereas in eyes with no current or prior PDR, the median corneal sensitivity was 4.75 cm (IQR 2.0-6.0, P < .0001). The median corneal sensitivity in eyes with regressed PDR was 0 cm (IQR 0-0.875), significantly lower than eyes with no current or prior PDR (4.5 cm, IQR 4.0, P = .0076) and no different than eyes with untreated PDR (0 cm, IQR 1.25). The odds of eyes with DR severity scale score ≥60 having complete corneal sensitivity loss was 3.6 times that of eyes with NPDR.

CONCLUSIONS

Corneal sensitivity is impaired in eyes with PDR compared to NPDR and is not rescued by anti-VEGF therapy. Assessment of corneal sensitivity in eyes with DR may identify patients at risk for additional complications, including neurotrophic keratopathy. NOTE: Publication of this article is sponsored by the American Ophthalmological Society.

Quantitative evaluation of ocular vascularity and correlation analysis in patients with diabetic retinopathy by SMI and OCTA

AIMS

To find potential relation between retrobulbar vessels and fundus microvessels and to detect sensitive and effective clinical indicators in predicting the progress of diabetic retinopathy (DR), ocular hemodynamics were measured using superb microvascular imaging (SMI) and ultrawide-field optical coherence tomography angiography (UWF-OCTA).

METHODS

Observational, cross-sectional study evaluating ocular hemodynamics in patients with DR by SMI (Aplio i900, Canon Medical) and UWF-OCTA (BM-400 K BMizar, Tupai Medical Technology). The peak systolic velocity (PSV), end-diastolic velocity (EDV), and resistive index (RI) of the central retinal artery (CRA), posterior ciliary artery (PCA), and ophthalmic artery (OA) were measured by SMI. UWF-OCTA evaluated the fundus vascular parameters. A correlation analysis was used to determine the correlation between SMI and UWF-OCTA parameters.

RESULTS

One hundred thirty-nine eyes of 139 diabetic patients were included: 29 without DR (NDR), 36 with mild to moderate nonproliferative DR (M-NPDR), 37 with severe NPDR (S-NPDR), and 37 with proliferative DR (PDR). PSV and EDV of retrobulbar vessels decreased from NDR to S-NPDR while increasing PDR. RI of OA showed a decreasing trend in the progression of DR, but other vessels didn't show the same trend. ROC curve analysis showed that CRAPSV, CRAEDV, PCAEDV, OAPSV, and OAEDV had diagnostic value distinguishing M-NPDR and S-NPDR. The correlation analysis observed a significant association between the SMI parameters of CRA and PCA and UWF-OCTA parameters. CRA hemodynamics were more associated with fundus vascular parameters, especially the retina, in the NDR group than in the M-NPDR group. In contrast, PCA consistently correlated with fundus vascular parameters, especially in the choroid, from the NDR to the M-NPDR group. However, OA showed a poor correlation with OCTA parameters.

CONCLUSION

The velocity of retrobulbar vessels, mainly the CRA, may serve as a valuable predictor for assessing the progress of DR. The use of SMI in diabetic patients may help identify patients at risk of developing retinopathy.

Anti-vascular endothelial growth factor therapy and retinal non-perfusion in diabetic retinopathy: A meta-analysis of randomised trials

PURPOSE

Retinal non-perfusion (RNP) is fundamental to disease onset and progression in diabetic retinopathy (DR). Whether anti-vascular endothelial growth factor (anti-VEGF) therapy can modify RNP progression is unclear. This investigation quantified the impact of anti-VEGF therapy on RNP progression compared with laser or sham at 12 months.

METHODS

A systematic review and meta-analysis of randomised controlled trials (RCTs) were performed; Ovid MEDLINE, EMBASE and CENTRAL were searched from inception to 4th March 2022. The change in any continuous measure of RNP at 12 months and 24 months was the primary and secondary outcomes, respectively. Outcomes were reported utilising standardised mean differences (SMD). The Cochrane Risk of Bias Tool version-2 and the Grading of Recommendations Assessment, Development and Evaluation (GRADE) guidelines informed risk of bias and certainty of evidence assessments.

RESULTS

Six RCTs (1296 eyes) and three RCTs (1131 eyes) were included at 12 and 24 months, respectively. Meta-analysis demonstrated that RNP progression may be slowed with anti-VEGF therapy compared with laser/sham at 12 months (SMD: -0.17; 95% confidence interval [CI]: -0.29, -0.06; p = 0.003; I2  = 0; GRADE rating: LOW) and 24-months (SMD: -0.21; 95% CI: -0.37, -0.05; p = 0.009; I2  = 28%; GRADE rating: LOW). The certainty of evidence was downgraded due to indirectness and due to imprecision.

CONCLUSION

Anti-VEGF treatment may slightly impact the pathophysiologic process of progressive RNP in DR. The dosing regimen and the absence of diabetic macular edema may impact this potential effect. Future trials are needed to increase the precision of the effect and inform the association between RNP progression and clinically important events.

PROSPERO REGISTRATION

CRD42022314418.

Retinal Ischaemia in Diabetic Retinopathy: Understanding and Overcoming a Therapeutic Challenge

BACKGROUND

Retinal ischaemia is present to a greater or lesser extent in all eyes with diabetic retinopathy (DR). Nonetheless, our understanding of its pathogenic mechanisms, risk factors, as well as other characteristics of retinal ischaemia in DR is very limited. To date, there is no treatment to revascularise ischaemic retina.

METHODS

Review of the literature highlighting the current knowledge on the topic of retinal ischaemia in DR, important observations made, and underlying gaps for which research is needed.

RESULTS

A very scarce number of clinical studies, mostly cross-sectional, have evaluated specifically retinal ischaemia in DR. Interindividual variability on its natural course and consequences, including the development of its major complications, namely diabetic macular ischaemia and proliferative diabetic retinopathy, have not been investigated. The in situ, surrounding, and distance effect of retinal ischaemia on retinal function and structure and its change over time remains also to be elucidated. Treatments to prevent the development of retinal ischaemia and, importantly, to achieve retinal reperfusion once capillary drop out has ensued, are very much needed and remain to be developed.

CONCLUSION

Research into retinal ischaemia in diabetes should be a priority to save sight.

Prognostic factors for the development and progression of proliferative diabetic retinopathy in people with diabetic retinopathy

BACKGROUND

Diabetic retinopathy (DR) is characterised by neurovascular degeneration as a result of chronic hyperglycaemia. Proliferative diabetic retinopathy (PDR) is the most serious complication of DR and can lead to total (central and peripheral) visual loss. PDR is characterised by the presence of abnormal new blood vessels, so-called "new vessels," at the optic disc (NVD) or elsewhere in the retina (NVE). PDR can progress to high-risk characteristics (HRC) PDR (HRC-PDR), which is defined by the presence of NVD more than one-fourth to one-third disc area in size plus vitreous haemorrhage or pre-retinal haemorrhage, or vitreous haemorrhage or pre-retinal haemorrhage obscuring more than one disc area. In severe cases, fibrovascular membranes grow over the retinal surface and tractional retinal detachment with sight loss can occur, despite treatment. Although most, if not all, individuals with diabetes will develop DR if they live long enough, only some progress to the sight-threatening PDR stage.  OBJECTIVES: To determine risk factors for the development of PDR and HRC-PDR in people with diabetes and DR.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL; which contains the Cochrane Eyes and Vision Trials Register; 2022, Issue 5), Ovid MEDLINE, and Ovid Embase. The date of the search was 27 May 2022. Additionally, the search was supplemented by screening reference lists of eligible articles. There were no restrictions to language or year of publication.  SELECTION CRITERIA: We included prospective or retrospective cohort studies and case-control longitudinal studies evaluating prognostic factors for the development and progression of PDR, in people who have not had previous treatment for DR. The target population consisted of adults (≥18 years of age) of any gender, sexual orientation, ethnicity, socioeconomic status, and geographical location, with non-proliferative diabetic retinopathy (NPDR) or PDR with less than HRC-PDR, diagnosed as per standard clinical practice. Two review authors independently screened titles and abstracts, and full-text articles, to determine eligibility; discrepancies were resolved through discussion. We considered prognostic factors measured at baseline and any other time points during the study and in any clinical setting. Outcomes were evaluated at three and eight years (± two years) or lifelong.  DATA COLLECTION AND ANALYSIS: Two review authors independently extracted data from included studies using a data extraction form that we developed and piloted prior to the data collection stage. We resolved any discrepancies through discussion. We used the Quality in Prognosis Studies (QUIPS) tool to assess risk of bias. We conducted meta-analyses in clinically relevant groups using a random-effects approach. We reported hazard ratios (HR), odds ratios (OR), and risk ratios (RR) separately for each available prognostic factor and outcome, stratified by different time points. Where possible, we meta-analysed adjusted prognostic factors. We evaluated the certainty of the evidence with an adapted version of the GRADE framework.   MAIN RESULTS: We screened 6391 records. From these, we identified 59 studies (87 articles) as eligible for inclusion. Thirty-five were prospective cohort studies, 22 were retrospective studies, 18 of which were cohort and six were based on data from electronic registers, and two were retrospective case-control studies. Twenty-three studies evaluated participants with type 1 diabetes (T1D), 19 with type 2 diabetes (T2D), and 17 included mixed populations (T1D and T2D). Studies on T1D included between 39 and 3250 participants at baseline, followed up for one to 45 years. Studies on T2D included between 100 and 71,817 participants at baseline, followed up for one to 20 years. The studies on mixed populations of T1D and T2D ranged from 76 to 32,553 participants at baseline, followed up for four to 25 years.  We found evidence indicating that higher glycated haemoglobin (haemoglobin A1c (HbA1c)) levels (adjusted OR ranged from 1.11 (95% confidence interval (CI) 0.93 to 1.32) to 2.10 (95% CI 1.64 to 2.69) and more advanced stages of retinopathy (adjusted OR ranged from 1.38 (95% CI 1.29 to 1.48) to 12.40 (95% CI 5.31 to 28.98) are independent risk factors for the development of PDR in people with T1D and T2D. We rated the evidence for these factors as of moderate certainty because of moderate to high risk of bias in the studies.  There was also some evidence suggesting several markers for renal disease (for example, nephropathy (adjusted OR ranged from 1.58 (95% CI not reported) to 2.68 (2.09 to 3.42), and creatinine (adjusted meta-analysis HR 1.61 (95% CI 0.77 to 3.36)), and, in people with T1D, age at diagnosis of diabetes (< 12 years of age) (standardised regression estimate 1.62, 95% CI 1.06 to 2.48), increased triglyceride levels (adjusted RR 1.55, 95% CI 1.06 to 1.95), and larger retinal venular diameters (RR 4.28, 95% CI 1.50 to 12.19) may increase the risk of progression to PDR. The certainty of evidence for these factors, however, was low to very low, due to risk of bias in the included studies, inconsistency (lack of studies preventing the grading of consistency or variable outcomes), and imprecision (wide CIs). There was no substantial and consistent evidence to support duration of diabetes, systolic or diastolic blood pressure, total cholesterol, low- (LDL) and high- (HDL) density lipoproteins, gender, ethnicity, body mass index (BMI), socioeconomic status, or tobacco and alcohol consumption as being associated with incidence of PDR. There was insufficient evidence to evaluate prognostic factors associated with progression of PDR to HRC-PDR.  AUTHORS' CONCLUSIONS: Increased HbA1c is likely to be associated with progression to PDR; therefore, maintaining adequate glucose control throughout life, irrespective of stage of DR severity, may help to prevent progression to PDR and risk of its sight-threatening complications. Renal impairment in people with T1D or T2D, as well as younger age at diagnosis of diabetes mellitus (DM), increased triglyceride levels, and increased retinal venular diameters in people with T1D may also be associated with increased risk of progression to PDR. Given that more advanced DR severity is associated with higher risk of progression to PDR, the earlier the disease is identified, and the above systemic risk factors are controlled, the greater the chance of reducing the risk of PDR and saving sight.

Vascular endothelial growth factor and its receptors regulation in gestational diabetes mellitus and eclampsia

Background

An imbalance in the expression of vascular endothelial growth factor (VEGF) and its receptor (VEGF-R) during pregnancy plays an important role in the pathogenesis of gestational diabetes mellitus (GDM) and eclampsia. VEGF and its receptors change during the regulation of blood vessels as a result of risk factors such as familial genetics. These modifications include loss of original balance of serological indicators, upregulation or downregulation of growth factor indicators, and changes in the placenta, kidney, liver and other organs to varying degrees of damage. This has an impact on both the pregnant woman's and the fetus's health.

Main body

This paper summarizes the mechanisms of unbalanced VEGF and receptor expression based on data from relevant literature on GDM and eclampsia. An Imbalance in VEGF and its binding receptor is often associated with the occurrence of multiple pregnancy disorders. In recent years, researchers have focused on the potential role of VEGF and its receptors in the development of GDM and eclampsia.

Conclusion

This paper summarizes the different VEGF subtypes and their binding receptors, as well as mechanisms that cause GDM and eclampsia, in order to provide valuable data to inform monitoring, diagnosis, and prognosis.

A Paradigm Shift in the Management Approaches of Proliferative Diabetic Retinopathy: Role of Anti-VEGF Therapy

Diabetic retinopathy (DR) is considered one of the leading causes of vision loss globally. It principally causes upregulation of pro-angiogenic, proinflammatory, and vascular permeability factors such as vascular endothelial growth factor (VEGF), leading to neovascularisation. The advanced stage of DR or proliferative diabetic retinopathy (PDR) is of more concern, as it leads to vitreous haemorrhage and traction retinal detachment. Various risk factors associated with PDR include hyperglycemia, hypertension, neuropathy, dyslipidemia, anaemia, nephropathy, and retinal complications of drugs used for diabetes. Current management approaches for PDR have been stratified and involve pan-retinal photocoagulation, vitrectomy, and anti-VEGF agents. Given the emerging role of anti-VEGF agents as a favourable adjunct or alternative therapy, they have a critical role in the management of PDR. The review emphasises current management approaches for PDR focusing on anti-VEGF therapy. The review also highlights the risk/benefit evaluation of the various approaches employed for PDR management in various clinical scenarios.

Diabetic macular ischemia

AIM

Since its relevance on diagnosis and prognosis of diabetic retinopathy (DR), this review will examine a multimodal imaging approach to detect diabetic macular ischemia (DMI).

METHODS

A PubMed engine search was carried out using the term "macular ischemia" paired with "diabetes," and "diabetic macular ischemia" paired to "fluorescein angiography," "ultra-wide field fluorescein angiography," "optical coherence tomography angiography," "octa," "2D octa," "ultra-wide field octa," "3D octa," "visual acuity." All studies published in English up to October 2021 irrespective of their publication status were reviewed, and relevant publications were included in this review.

RESULTS

Recently, new technologies have been proposed as an alternative to fluorescein angiography (FA), which is an actual diagnostic gold standard technique. Nowadays, optical coherence tomography angiography (OCTA) has emerged as the most promising and reliable procedure able to provide a qualitative and quantitative description of DMI. Newer three-dimensional (3D) OCTA approach will be discussed too. Moreover, we will discuss how OCTA might identify preclinical alterations before the onset of DR and allow prediction about the progression of disease.

CONCLUSION

OCTA has significantly expanded our knowledge on diabetic macular ischemia.