Retinal Microvasculature and Visual Acuity after Intravitreal Aflibercept in Diabetic Macular Edema: An Optical Coherence Tomography Angiography Study

Macular Ischemia Changes in Patients with Diabetic Macular Edema Treated with Aflibercept and Ranibizumab

Τhis study aims to assess changes in the fovea avascular zone (FAZ) in treatment naïve patients receiving aflibercept or ranibizumab injections for diabetic macular edema (DME). Best corrected visual acuity (BCVA) testing, OCT, and OCT-angiography imaging were performed at baseline and 1 month after each injection. Injections of either aflibercept or ranibizumab were administered monthly for 6 consecutive months. FAZ in the superficial (SCP) and the deep capillary plexus (DCP) using OCT angiography was recorded for each visit. Fifty eyes from fifty patients with a mean age of 67.0 ± 10.7 years were included in the study. Twenty-five patients received aflibercept and twenty-five received ranibizumab. BCVA was 40.8 ± 10.0 and increased to 52.1 ± 7.9 ETDRS letters at the last visit (p < 0.001). CRT was 295.6 ± 34.0 at baseline and 247.9 ± 29.7 at the last study visit (p < 0.001). SCP FAZ was 350.6 ± 79.5 μm2 at baseline and 339.0 ± 71.3 μm2 after sox monthly injections (p = 0.132). DCP FAZ was 558.6 ± 199.0 μm2 at baseline and 459.5 ± 156.1 μm2 after six monthly injections (p < 0.001). There was no effect of the choice of ranibizumab or aflibercept on DCP FAZ change (p = 0.277). In conclusion, treatment with 6 monthly injections of ranibizumab and aflibercept led to an increase in BCVA and a decrease in CRT and DCP FAZ area. Both drugs led to an improvement in DCP ischemia.

Optical coherence tomography angiography analysis of choroidal microvasculature in various forms of diabetic macular edema

INTRODUCTION

Optical coherence tomography angiography (OCTA) research in diabetic macular edema (DME) has focused on the retinal microvasculature with little attention to the choroid. The goal of this study was to analyze the association between quantitative choroidal OCTA parameters and various forms of DME observed on optical coherence tomography.

METHODS

We conducted a retrospective study of 61 eyes of 53 patients with DME. DME was classified as early or advanced, and as sponge-like diffuse retinal thickening (DRT), cystoid macular edema (CME) or serous retinal detachment (SRD). Quantitative OCTA parameters (vessel density [VD] in the superficial capillary plexus [SCP], middle capillary plexus [MCP], deep capillary plexus [DCP] and choriocapillaris [CC]) were recorded.

RESULTS

The VD in the CC and SCP was significantly higher in patients with early DME compared to patients with advanced DME (P value<0.01). CC VD was lower in subjects with SRD compared to DRT and CME (P value<0.001). Moreover, it was lower in CME compared to DRT (P value<0.05). No statistical differences were found between VD in the MCP and DCP (P value>0.05). Furthermore, CC VD was lower in patients with increased retinal thickness, disruption of the ellipsoid zone (EZ) or external limiting membrane (ELM), and disorganization of the inner retinal layers (DRIL) (P value<0.05).

CONCLUSION

CC ischemia plays an important role in the pathogenesis of DME. We demonstrated a decrease in CC VD in patients with severe DME, SRD, retinal thickening, EZ and/or ELM disruption and DRIL.

Structure-function associations between contrast sensitivity and widefield swept-source optical coherence tomography angiography in diabetic macular edema

PURPOSE

To evaluate the relationship between contrast sensitivity (CS) and widefield swept-source optical coherence tomography angiography (WF SS-OCTA) vascular metrics in diabetic macular edema (DME) was the purpose.

METHODS

This prospectively enrolled cross-sectional observational study included 61 eyes of 48 patients that were tested with the quantitative CS function (qCSF) test on the same day as imaging with WF SS-OCTA (PLEX® Elite 9000, Carl Zeiss Meditec) 3 × 3, 6 × 6, and 12 × 12 mm scans. Outcomes included visual acuity (VA) and multiple qCSF metrics. Vascular metrics included vessel density (VD) and vessel skeletonized density (VSD) in the superficial (SCP) and deep capillary plexus (DCP) and whole retina (WR) and foveal avascular zone (FAZ) parameters. Mixed effects multivariable linear regression models controlling for age, lens status, and diabetic retinopathy stage were performed. Standardized beta coefficients were calculated by refitting the standardized data.

RESULTS

SS-OCTA metrics had a significant association with CS and VA. The effect size of OCTA metrics was larger on CS compared to VA. For example, the standardized beta coefficients for VSD and CS at 3 cpd (βSCP = 0.76, βDCP = 0.71, βWR = 0.72, p < 0.001) were larger than those for VA (βSCP =  - 0.55, p < 0.001; βDCP =  - 0.43, p = 0.004; βWR =  - 0.50, p < 0.001). On 6 × 6 mm images, AULCSF, CS at 3 cpd, and CS at 6 cpd were significantly associated with VD and VSD in all three slab types (SCP, DCP, and WR), while VA was not.

CONCLUSION

Structure-function associations in patients with DME leveraging the qCSF device suggest microvascular changes on WF SS-OCTA are associated with larger changes in contrast sensitivity than VA.

OCTA changes following loading phase with intravitreal aflibercept for DME

OBJECTIVE

To quantify changes in optical coherence tomography angiography (OCTA) parameters following intravitreal anti-vascular endothelial growth factor treatment for diabetic macular edema (DME), and to assess associations between pretreatment OCTA parameters and visual outcomes.

DESIGN

Prospective cohort study.

METHODS

Twenty-nine patients with DME received 5 monthly intravitreal injections of aflibercept. OCTA data obtained at baseline and at 6 months were compared using the Wilcoxon signed-rank test. OCTA parameters were foveal avascular zone (FAZ) area, FAZ perimeter, FAZ circularity, vessel density in the superficial vascular plexus (segmented into central, inner, outer, and full Early Treatment of Diabetic Retinopathy Study [ETDRS] map regions. Subanalysis divided patients into treatment responders (reduction of central subfield thickness >50 µm over treatment) and nonresponders. Associations between pretreatment OCTA parameters and visual acuity outcomes were analyzed using multivariable linear and logistic regression.

RESULTS

A total of 29 patients were included: 25 patients (86.2%) had nonproliferative diabetic retinopathy, and 4 patients (13.8%) had proliferative diabetic retinopathy. Vessel density was reduced in the central (p = 0.004) and inner (p = 0.013) ETDRS map regions. This effect was significant only among treatment responders (central p = 0.002; inner p = 0.017). Pretreatment OCT and OCTA parameters were not associated with final visual acuity outcomes.

CONCLUSION

Following intravitreal aflibercept treatment for DME, there was a significant decrease in vessel density of the superficial vascular plexus at the central and inner ETDRS map regions. This was seen only among treatment responders. Observations here are likely to represent the limits of OCTA technology itself, where pretreatment vessel density may have been artifactually overestimated by suspended scattering particles in motion. Pretreatment OCTA parameters did not serve as biomarkers for visual outcome following anti-vascular endothelial growth factor therapy.

Tetrahedral framework nucleic acids inhibit pathological neovascularization and vaso-obliteration in ischaemic retinopathy via PI3K/AKT/mTOR signalling pathway

This study aimed to explore the effect and the molecular mechanism of tetrahedral framework nucleic acids (tFNAs), a novel self-assembled nanomaterial with excellent biocompatibility and superior endocytosis ability, in inhibition of pathological retinal neovascularization (RNV) and more importantly, in amelioration of vaso-obliteration (VO) in ischaemic retinopathy. tFNAs were synthesized from four single-stranded DNAs (ssDNAs). Cell proliferation, wound healing and tube formation assays were performed to explore cellular angiogenic functions in vitro. The effects of tFNAs on reducing angiogenesis and inhibiting VO were explored by oxygen-induced retinopathy (OIR) model in vivo. In vitro, tFNAs were capable to enter endothelial cells (ECs), inhibit cell proliferation, tube formation and migration under hypoxic conditions. In vivo, tFNAs successfully reduce RNV and inhibit VO in OIR model via the PI3K/AKT/mTOR/S6K pathway, while vascular endothelial growth factor fusion protein, Aflibercept, could reduce RNV but not inhibit VO. This study provides a theoretical basis for the further understanding of RNV and suggests that tFNAs might be a novel promising candidate for the treatment of blind-causing RNV.

Retinal Microvascular Changes after Intravitreal Triamcinolone Acetonide in Diabetic Macular Edema

Intravitreal injection of triamcinolone acetonide (TA) is essential for clinical treatment in patients who insufficiently respond to vascular endothelial factor inhibitors for diabetic macular edema (DME). The aim of this study was to investigate microvascular changes treated with TA using optical coherence tomography angiography (OCTA). After TA in twelve eyes of eleven patients with central retinal thickness (CRT), there was a 20% or more reduction observed. Visual acuity, the number of microaneurysms, vessel density, and the foveal avascular zone (FAZ) area were compared before and at 2 months after TA. At baseline, the number of microaneurysms was 2.1 ± 1.1 in the superficial capillary plexuses (SCP) and 2.0 ± 1.1 in the deep capillary plexuses (DCP), with a significant decrease post-treatment to 1.0 ± 1.0 for SCP and 0.8 ± 0.8 for DCP (SCP; p = 0.018, DCP; p = 0.008). There was significant enlargement of the FAZ area from 0.28 ± 0.11 mm² to 0.32 ± 0.14 mm² (p = 0.041). There was no significant difference in the visual acuity and vessel density of SCP and DCP. Results indicated that OCTA was useful for the evaluation of qualitative and morphological retinal microcirculation and that intravitreal TA may decrease microaneurysms.

Preliminary Report on Optical Coherence Tomography Angiography Biomarkers in Non-Responders and Responders to Intravitreal Anti-VEGF Injection for Diabetic Macular Oedema

PURPOSE

To identify optical coherence tomography angiography (OCTA) biomarkers in patients who were treated for diabetic macular oedema (DME) with intravitreal anti-vascular endothelial growth factor (VEGF) injections and compare the OCTA parameters between responders and non-responders.

METHODS

A retrospective cohort study of 61 eyes with DME who received at least one intravitreal anti-VEGF injection was included between July 2017 and October 2020. The subjects underwent a comprehensive eye examination followed by an OCTA examination before and after intravitreal anti-VEGF injection. Demographic data, visual acuity, and OCTA parameters were documented, and further analysis was performed pre- and post-intravitreal anti-VEGF injection.

RESULTS

Out of 61 eyes which underwent intravitreal anti-VEGF injection for diabetic macular oedema, 30 were responders (group 1) and 31 were non-responders (group 2). We found that the responders (group 1) had a higher vessel density in the outer ring that was statistically significant (p = 0.022), and higher perfusion density was noted in the outer ring (p = 0.012) and full ring (p = 0.044) at levels of the superficial capillary plexus (SCP). We also observed a lower vessel diameter index in the deep capillary plexus (DCP) in responders when compared to non-responders (p < 0.00).

CONCLUSION

The evaluation of SCP in OCTA in addition to DCP can result in a better prediction of treatment response and early management in diabetic macular oedema.

Predictive factors for treatment outcomes with intravitreal anti-vascular endothelial growth factor injections in diabetic macular edema in clinical practice

BACKGROUND

Intravitreal anti-vascular endothelial growth factor (anti-VEGF) injections are the standard of care for diabetic macular edema (DME), a common complication of diabetes. This study aimed to identify factors influencing DME intravitreal anti-VEGF treatment outcomes in real-world practice.

METHODS

This was a multi-center retrospective observational study using medical chart review of participants receiving anti-VEGF injections for DME (N = 248). Demographic and clinical variables were assessed for association with best corrected visual acuity (BCVA) and central macular thickness (CMT) outcomes using regression models.

RESULTS

There was a significant improvement in BCVA (p < 0.001) and CMT (p < 0.001) after 12 months of treatment, although 21% of participants had decreased BCVA, and 41% had a < 10% CMT reduction at 12 months. Higher baseline BCVA (p = 0.022, OR=-0.024, 95% CI=-0.046,-0.004) and longer duration of diabetic retinopathy (p = 0.048, OR=-0.064, 95% CI=-0.129,-0.001) were negative predictors for BCVA response, whereas Aflibercept treatment (p = 0.017, OR = 1.107, 95% CI = 0.220,2.051) compared with other drugs and a positive "early functional response" (p < 0.001, OR=-1.393, 95% CI=-1.946,-0.857) were positive predictors. A higher baseline CMT (p < 0.001, OR = 0.019, 95% CI = 0.012,0.0261) and an "early anatomical response", (p < 0.001, OR=-1.677, 95% CI=-2.456, -0.943) were predictors for greater reduction in CMT. Overall, the variables could predict only 23% of BCVA and 52% of CMT response.

CONCLUSIONS

The study shows a significant proportion of DME patients do not respond to anti-VEGF therapy and identifies several clinical predictors for treatment outcomes.

TRIAL REGISTRATION

The study was approved through the Human Research Ethics Committee, University of Tasmania (approval number H0012902), and the Southern Adelaide Clinical Human Research Ethics Committee (approval number 86 - 067).

Persistent diabetic macular edema: Definition, incidence, biomarkers, and treatment methods

Intravitreal antivascular endothelial growth factor (anti-VEGF) treatment has drastically improved the visual and anatomical outcomes in patients with diabetic macular edema (DME); however, success is not always guaranteed, and a proportion of these eyes demonstrate persistent DME (pDME) despite intensive treatment. While standardized criteria to define these treatment-resistant eyes have not yet been established, many studies refer to eyes with no clinical response or an unsatisfactory partial response as having pDME. A patient is considered to have pDME if the retinal thickness improves less than 10-25% after 6 months of treatment. A range of treatment options have been recommended for eyes with pDME, including switching anti-VEGF agents, using corticosteroids and/or antioxidant drugs in adjunct with anti-VEGF therapy, and vitrectomy. In addition, multimodal imaging of DME eyes may be advantageous in predicting the responsiveness to treatment; this is beneficial when initiating alternative therapies. We explore the literature on persistent DME regarding its defining criteria, incidence, the baseline biological markers that may be useful in anticipating the response to treatment, and the available treatment options.

Morphological and functional changes in the macular area in diabetic macular edema after a single intravitreal injection of aflibercept

AIM

To evaluate the changes in macular morphology and function after a single intravitreal injection of aflibercept in diabetic macular edema (DME) using optical coherence tomography angiography (OCTA) and MP-3 microperimetry.

METHODS

Twenty-eight patients (42 eyes) diagnosed with DME were treated with intravitreal injection of aflibercept. The changes in best corrected visual acuity (BCVA), central retinal thickness (CRT), foveal avascular zone (FAZ) area, vessel density of superficial retinal capillary plexus (SVD), vessel density of deep retinal capillary plexus (DVD), mean light sensitivity (MLS), 2° fixation rate (P1), 4° fixation rate (P2), and other indicators 1mo after treatment were compared; of these, BCVA was converted into logarithm of the minimum angle of resolution (logMAR), and the correlation among the factors was analyzed.

RESULTS

After treatment, logMAR BCVA was 0.47±0.24, which was significantly better than that before treatment (0.63±0.28, P<0.001). The CRT was 359.21±107.87 µm after treatment, which was significantly lower than before treatment (474.10±138.20 µm, P<0.001). The FAZ area, SVD, and DVD were not significantly changed after treatment compared with the baseline. MLS was 22.16±4.20 dB after treatment, which was significantly higher than before treatment (19.63±4.23 dB, P<0.001). P2 significantly increased after treatment than before treatment (P=0.007). P1 had no significant change after treatment than before treatment (P=0.086).

CONCLUSION

A single intravitreal injection of aflibercept effectively reduces macular edema and improves retinal sensitivity, fixation stability, and visual acuity, possibly without causing significant changes in the retinal vascular condition in a short time.

The Impact of Residual Retinal Fluid Following Intravitreal Anti-Vascular Endothelial Growth Factor Therapy for Diabetic Macular Edema and Macular Edema Secondary to Retinal Vein Occlusion: A Systematic Review

The association between residual retinal fluid and visual acuity for diabetic macular edema (DME) and macular edema (ME) secondary to retinal vein occlusion (RVO) is not well established. We conducted a systematic literature search for peer-reviewed articles reporting on visual acuity stratified by subretinal fluid (SRF), intraretinal fluid (IRF), or any retinal fluid at final follow-up after intravitreal anti-vascular endothelial growth factor therapy injection for treatment of DME or ME secondary to RVO. Two observational studies on ME secondary to RVO and one study for DME found no significant differences between eyes with and without residual retinal fluid for final BCVA. One randomized controlled trial (RCT) found that eyes with residual retinal fluid had significantly worse final best-corrected visual acuity in ME secondary to RVO, whereas another RCT found no significant difference for DME. There is a paucity of evidence examining the impact of residual retinal fluid on visual acuity in DME and ME secondary to RVO. The limited evidence suggests that aggressive fluid resolution is worthwhile. [Ophthalmic Surg Lasers Imaging Retina 2023;54:50-58.].

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.

Optical Coherence Tomography Angiography Biomarkers Predict Anatomical Response to Bevacizumab in Diabetic Macular Edema

PURPOSE

To identify biomarkers that may predict an early anatomical response to the treatment of diabetic macular edema (DME) with intravitreal bevacizumab (IVB) by means of optical coherence tomography angiography (OCTA).

METHODS

This study is a retrospective study of treatment-naïve patients with DME who underwent 6 × 6 mm OCTA imaging of the macula at baseline and after three monthly IVB injections. Thirty-six eyes of 23 patients were included. Eyes that demonstrated evidence of an early anatomical response, consisting of a >10% decrease in central macular thickness (CMT) (n = 18), were compared with those eyes that failed to show such an improvement (n = 18).

RESULTS

At baseline, early-response eyes had worse starting best-corrected visual acuity (BCVA, LogMAR 0.84 ± 0.41 versus LogMAR 0.51 ± 0.15, p = 0.004) and a larger CMT (490 ± 135 µm versus 356 ± 33 µm, p = 0.001), but smaller foveal avascular zones (FAZ) (0.309 ± 0.098mm versus 0.413 ± 0.095 mm, p = 0.003) compared with eyes that proved refractory to three monthly injections of IVB. The vascular density (VD) in both the foveal superficial and deep capillary plexuses was significantly greater in eyes that showed an early-treatment response compared with eyes that were non-responders (24.86 ± 6.90% versus 19.98 ± 7.13%, p = 0.045 and 32.30 ± 4.88% versus 26.95 ± 7.25%, p = 0.028, respectively). Early-treatment response to IVB was predicted by starting CMT (r ²= 0.266, p = 0.001), FAZ size (r ²= 0.234, p = 0.003), and VD in the superficial parafovea (r ²= 0.217, p = 0.004) and deep fovea (r ²= 0.157, p = 0.037).

CONCLUSION

Projection-resolved OCTA may be useful in predicting an early anatomical response of DME to treatment with IVB.

Response to 1-Year Fixed-Regimen Bevacizumab Therapy in Treatment-Naïve DME Patients: Assessment by OCT Angiography

PURPOSE

To evaluate the effectiveness of intravitreal bevacizumab treatment in patients with diabetic macular edema (DME) by assessing retinal changes using optical coherence tomography angiography (OCT-A).

METHODS

This prospective study was performed in patients with treatment-naïve DME. The eyes of patients were imaged using a swept-source OCT system with a scan area of 6 × 6 mm. The DME patients with a central macular thickness (CMT) of ≥300 μm received nine bevacizumab injections within 12 months. The demographic, systemic, and ocular parameters, including the best-corrected visual acuity (BCVA), CMT, microaneurysm (MA) count, and foveal avascular zone (FAZ) area in both superficial capillary plexus (SCP) and deep capillary plexus (DCP), as well as vessel density in SCP, were assessed in the patients. In addition, the response (good or poor) of the DME eyes to bevacizumab treatment and the final visual acuity (BCVA of 75 letters) were analyzed.

RESULTS

Seventy-seven eyes of DME patients were subjected to the final analysis. Bevacizumab treatment reduced CMT from 425.06 μm (±77.15) to 350.25 μm (±82.04) and improved BCVA by about 8.61 letters (from 64.73 to 73.34) in the patients. The mean number of MAs in SCP decreased from 3.51 ± 2.07 to 2.31 ± 1.15 (p < 0.001) and in DCP from 17.12 ± 11.56 to 12.21 ± 6.99 (p < 0.001), whereas the area of FAZ increased in SCP from 328.22 ± 131.38 to 399.70 ± 156.98 (p < 0.001) and in DCP from 571.13 ± 396.01 to 665.89 ± 412.77 (p = 0.001). The final BCVA letter score and CMT were statistically significant in both poor and good responders, as well as in BCVA < 75 and BCVA ≥ 75 groups.

CONCLUSION

The fixed-regimen intravitreal bevacizumab therapy was effective in treating DME. Apart from noninvasive visualization of microvascular damage, OCT-A showed limited usefulness in predicting treatment response. Although the study showed that the number of MAs was significantly reduced during treatment, which is an OCT-A predictor of a good response to bevacizumab treatment at a 12-month visit, commonly observed artifacts may reduce the usefulness of OCT-A.

Macular and peripapillary microvasculature after dexamethasone injection in diabetic macular edema

PURPOSE

To evaluate the microvascular changes in the macular and peripapillary area after intravitreal dexamethasone implant in diabetic macular edema (DME).

MATERIAL AND METHODS

We included 31 eyes of 31 patients treated with a single dose dexamethasone implant for DME. All subjects underwent swept-source optical coherence tomography (OCT) and OCT angiography imaging before (T0), and one month (T1), two months (T2), and four months (T4) after dexamethasone injection. The foveal avascular zone (FAZ) area of superficial and deep capillary plexus (SCP and DCP) was calculated by delineating the FAZ border using the measurement tool of the device. The vessel density (VD) of SCP and DCP and choriocapillaris (CC) in the macular and peripapillary area were automatically calculated.

RESULTS

There was an insignificant reduction in FAZ area measurements of SCP after dexamethasone injection in DME patients (p = 0.846). The FAZ area of DCP were significantly smaller compared to T0 measurements at T1, T2, and T4 (p = 0.013, p = 0.031, and p = 0.029, respectively). The mean average parafoveal VD measurements were significantly decreased after dexamethasone injection in SCP and DCP (p = 0.004, p = 0.005). The peripapillary VD in retinal capillary plexuses and choriocapillaris showed no significant difference after dexamethasone injection.

CONCLUSION

Intravitreal dexamethasone leads to a significant FAZ area decrease in DCP with a reduction in parafoveal VD measurements. In addition, no significant VD changes were observed in the peripapillary area after dexamethasone. These findings indicate that dexamethasone may improve macular ischemia with no significant effects on peripapillary microvasculature in DME patients.

Review on Recent Trials Evaluating the Effect of Intravitreal Injections of Anti-VEGF Agents on the Macular Perfusion of Diabetic Patients with Diabetic Macular Edema

Background

Diabetic macular edema (DME) is a major cause of vision loss in diabetics worldwide. Anti-vascular endothelial growth factor (anti-VEGF) agents have become the mainstay of treatment of vision loss due to DME. Long-term effects of these agents on the macular perfusion (MP) are a current concern.

Objective

To review recently published studies that evaluated the effect of intravitreal injection of anti-VEGF agents on the MP of diabetics with DME.

Methods

Different databases were searched including PubMed, Medline, Ovid, Science Direct, and Google Scholar for relevant studies published between 2010 and 2019. All studies found were compared regarding methodology and results and included in this review. Some studies relating to retinal perfusion in general and not strictly MP were also included for comprehensiveness.

Results

Several studies utilizing different anti-VEGF agents were identified. All the large randomized controlled clinical trials identified utilized primarily fluorescein angiography (FA) and human graders and found generally no worsening of MP associated with anti-VEGF agents use in diabetic patients with DME. Some of these studies, however, depended on post-hoc analysis. Several more recent, but smaller case series, have utilized the relatively new and non-invasive optical coherence tomography angiography (OCTA) in this evaluation and found more conflicting results.

Conclusion

The large clinical trials recently performed depended mainly on FA in the analysis of MP changes following injections and generally found no worsening of MP. More recently, smaller case series have utilized OCTA in this analysis, yielding more conflicting results. Large randomized controlled trials using OCTA are thus needed.

EIGHTEEN-MONTH RESULTS OF INTRAVITREAL ANTI-VASCULAR ENDOTHELIAL GROWTH FACTOR ON VISION AND MICROCIRCULATION IN RADIATION MACULOPATHY

PURPOSE

To evaluate 18 months' results of a strict anti-vascular endothelial growth factor protocol for radiation maculopathy following proton therapy in choroidal melanoma.

METHODS

Retrospective, comparative, nonrandomized study of 74 radiation maculopathy patients presenting macular lipid deposits, hemorrhages, microaneurysms, cystoid edema, nerve layer infarction, telangiectasia, or capillary nonperfusion. The study group included 52 consecutive patients injected with intravitreal anti-vascular endothelial growth factors (bevacizumab/ranibizumab: 46/6) every two months for the first and every 3 months for the second year, with minimum 12 months' follow-up. The control group consisted of 22 patients having declined this treatment. Best-corrected visual acuity, spectral domain-optical coherence tomography and optical coherence tomography angiography were recorded at baseline, 6, 12, and 18 months. The foveal avascular zone and capillary density were measured at the superficial capillary plexus.

RESULTS

Radiation maculopathy was diagnosed at 2 years (1.5-3.5) after proton therapy. Best-corrected visual acuity at baseline, 12 and 18 months improved in the study group from 0.45, 0.3 to 0.2 logarithm of the minimum angle of resolution, but decreased in the control group from 0.5, 0.9 to 1.0 logarithm of the minimum angle of resolution respectively (P < 0.001 at 12 months). Simultaneously, foveal avascular zone enlargement was less in the study (from 0.377, 0.665 to 0.744 mm2) than control group (from 0.436, 1.463 to 2.638 mm2) (P = 0.05 at 12 months). CMT (280 and 276 µm) and capillary density (37% and 38%, at baseline, respectively) did not evolve significantly different.

CONCLUSION

Intravitreal anti-vascular endothelial growth factors, every 2 months for the first and every 3 months for the second year, slow down, over up to 18 months, vision loss and anatomical degradation in radiation maculopathy following proton therapy for choroidal melanoma.

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.

Twenty-Four-Month OCTA Assessment in Diabetic Patients Undergoing Fixed-Interval Intravitreal Aflibercept Therapy

BACKGROUND AND OBJECTIVE

Evaluate capillary perfusion density (CPD) in patients with diabetic macular edema (DME) undergoing fixed intravit-real aflibercept injections (IAI) through 24 months.

PATIENTS AND METHODS

Prospective, interventional, single-arm study enrolling 20 patients with persistent DME. Patients received IAI every 4 weeks until DME resolution followed by extension to every 8 weeks. Optical coherence tomography angiography was obtained at baseline, 6, 12, and 24 months.

RESULTS

Sixteen of 20 eyes completed the study. Baseline mean central subfield thickness was 420 µm, which improved to 251 µm (P < .001). The mean best-corrected visual acuity (BCVA) improved by 5.5 letters (P = .042). The whole superficial CPD decreased by 5.3% (P = .001) and the deep CPD decreased by 4.4% (P = .009). Better BCVA correlated with less CPD loss within the superficial parafovea (r = +0.66 [0.23, 0.88]; P = .006) and whole (r = +0.60 [0.12, 0.85]; P = .017) areas.

CONCLUSION

Superficial and deep CPD decreased despite fixed IAI through 24 months. [Ophthalmic Surg Lasers Imaging Retina. 2020;51:448-455.].

Mean macular intercapillary area in eyes with diabetic macular oedema after anti-vascular endothelial growth factor therapy and its association with treatment response

BACKGROUND

To evaluate the changes in the mean macular intercapillary area (ICA) from sequential enface optical coherence tomography angiography (OCTA) images following intravitreal anti-vascular endothelial growth factor (VEGF) therapy in initially treatment-naïve eyes with diabetic macular oedema (DME).

METHODS

In this multicentre retrospective study, 6 × 6 and 3 × 3 mm customised, total retinal projection enface OCTA images were collected and processed for quantitative assessment of ICA by a customised MATLAB software. Measurements were done in concentric regions centred on the fovea-with the exclusion of foveal avascular zone (FAZ)-in 0.5 mm diameter increments as well as within the intervening rings.

RESULTS

In this study, 6 × 6 mm OCTA images from 46 eyes of 29 patients, and 3 × 3 mm OCTA images from 23 eyes of 15 patients were included. There was no significant change in mean ICA after treatment in either scan size or in any measurement regions (all p > 0.05). Multivariate analysis revealed that baseline BCVA was significantly correlated with the visual outcome (p = 0.039). Additionally, after correction for age, baseline central retinal thickness (CRT), baseline BCVA, and retinopathy severity, mean ICA in the 1.5 mm circle was found to be a significant predictor of post treatment CRT, (p = 0.006).

CONCLUSIONS

Absence of significant change in mean ICA after a minimum of three intravitreal anti-VEGF injections, may indicate that, in the short term, anti-VEGF injections neither impair nor improve macular perfusion in DME. Baseline BCVA was found to be a robust predictor of functional outcome, while inner mean ICA was a significant predictor for macular thickness outcomes.

Optical Coherence Tomography Angiography of Macular Perfusion Changes after Anti-VEGF Therapy for Diabetic Macular Edema: A Systematic Review

BACKGROUND

Diabetic macular edema (DME) is a major cause of vision loss in diabetics that is currently mainly treated by antivascular endothelial growth factor (VEGF) agents. The effect of these agents on macular perfusion (MP) is a current concern. Optical coherence tomography angiography (OCTA) is an imaging modality that allows noninvasive high-resolution retinal microvasculature imaging. Several recent studies evaluated the effect of anti-VEGF agents on the MP of DME patients using OCTA. Our aim is to provide a systematic review of these studies.

METHODS

Multiple databases were searched including PubMed, Ovid Medline, EMBASE, and Google Scholar for relevant studies published between January 2016 and November 2020 which were included in this review. Studies were compared regarding their design, the number of included patients, the machine and scanning protocol used, the inclusion and exclusion criteria, the number of injections given, the type of anti-VEGF agent used, the outcome measures assessed, and the effect of injections on different MP parameters.

RESULTS

A total of 16 studies were included. The studies assessed various OCTA parameters that define MP including the foveal avascular zone area and superficial and deep vascular density and yielded conflicting results. Seven studies showed stable or improved MP following treatment, while 7 studies showed worsening MP following treatment, and 2 studies showed inconclusive results. This could have been due to differences in study design, inclusion criteria, type of anti-VEGF agents used, treatment duration, and methods of image analysis and vascular density quantification. All identified studies were noncomparative case series, and 14 of them (87.5%) used the RTVue XR Avanti OCTA machine. Only one study compared OCTA to fluorescein angiography findings.

CONCLUSION

Analysis of MP changes following VEGF inhibition for DME could benefit from a unified scanning protocol and analysis approach that uses similar study designs to eliminate potential sources of bias. This may provide more definitive conclusions regarding the effect of treatment on MP.

Monoclonal Antibodies: A Prospective and Retrospective View

BACKGROUND

Monoclonal Antibodies (mAbs) represent one of the most important classes of biotherapeutic agents. They are used to cure many diseases, including cancer, autoimmune diseases, cardiovascular diseases, angiogenesis-related diseases and, more recently also haemophilia. They can be highly varied in terms of format, source, and specificity to improve efficacy and to obtain more targeted applications. This can be achieved by leaving substantially unchanged the basic structural components for paratope clustering.

OBJECTIVES

The objective was to trace the most relevant findings that have deserved prestigious awards over the years, to report the most important clinical applications and to emphasize their latest emerging therapeutic trends.

RESULTS

We report the most relevant milestones and new technologies adopted for antibody development. Recent efforts in generating new engineered antibody-based formats are briefly reviewed. The most important antibody-based molecules that are (or are going to be) used for pharmacological practice have been collected in useful tables.

CONCLUSION

The topics here discussed prove the undisputed role of mAbs as innovative biopharmaceuticals molecules and as vital components of targeted pharmacological therapies.

Macular microvascular changes after intravitreal bevacizumab injection in diabetic macular edema

OBJECTIVE

To evaluate the changes in retinal capillary plexus and the choriocapillaris after a single intravitreal injection of bevacizumab in eyes with diabetic macular edema using optical coherence tomography angiography (OCTA).

DESIGN

Prospective interventional case series.

PARTICIPANTS

Patients having diabetes with centre-involving diabetic macular edema.

METHODS

In this prospective interventional case series, eyes with centre-involving diabetic macular edema were enrolled. Vascular density (VD), vascular diameter index (VDI), vascular length density (VLD), foveal avascular zone (FAZ) area, and foveal density (FD)-300 were measured using en face OCTA images before and 1 month after administration of intravitreal bevacizumab. VD and VDI measurements were performed in the superficial capillary plexus (SCP) and deep retinal capillary plexus (DCP) and in the choriocapillaris. Additionally, capillary nonperfusion area (CNPA) was detected automatically based on vessel distance map in 4 concentric rings around the foveal centre. The segmentation error was manually corrected, and the measurements were performed by 2 expert graders.

RESULTS

Twenty-three eyes of 19 patients with a mean age of 62.76 ± 6.88 years were included. There were no significant changes in the FAZ area, FD-300, or in the VD of the foveal and parafoveal SCP and DCP. Also, VLD and VDI of the SCP and DCP remained unchanged. The change in the CNPA was not statistically significant. The VD of choriocapillaris increased significantly after injections (p = 0.005).

CONCLUSIONS

FAZ area and VD of the retinal capillary plexus remained stable in the short-term period after intravitreal bevacizumab. In addition, the choriocapillaris blood flow improved after bevacizumab injection.

Profile of non-responder and late responder patients treated for diabetic macular edema: systemic and ocular factors

Diabetic macular edema (DME) treatment represents a challenge for the ophthalmologists, and several aspects of real treatment expectancy are still being discussed and not yet fully elucidated. A univocal definition of responsiveness to treatment has not been reached. How the clinicians can evaluate the therapeutic success? The evaluation of systemic and ocular factors should help in this complex management. The age influences the long-term outcomes, and the role of glycemic control is confounded by contrasting correlations between hemoglobin glycated A1c and DME. Long-term treatment success is influenced by baseline best-corrected visual acuity (BCVA), central macular thickness (CMT) and early BCVA response. Also baseline diabetic retinopathy severity scale score is useful to evaluate the chances of improvement before and during treatments. The time-switching was influenced by early BCVA response, however considering a delayed response in a percentage of patients. Several structural optical coherence tomography (OCT) findings could predict long-term success, as the presence of serous retinal detachment, hyperreflective retinal spots, the disruption of external limiting membrane and ellipsoid zone, the disorganization of inner retinal layers and continued increase in CMT were considered predictors of poor response to treatment. Foveal avascular zone enlargement, high number of microaneurysms (Mas), lower vessel density (VD) in deep capillary plexus and lower parafoveal VD in superficial capillary plexus were considered as OCT angiography biomarkers of poor responsiveness. The aim of this review is to report the factors that could influence the response to treatment of DME patients.

Macular vessel density in diabetes and diabetic retinopathy with swept-source optical coherence tomography angiography

PURPOSE

Previous studies on the association between macular vessel density (VD) and diabetic retinopathy had conflicting conclusions. This study assessed the alterations of macular VD, as well as other factors, in diabetic patients using swept-source optical coherence tomography angiography (SS-OCTA) in a large-scale sample from Chinese communities.

METHODS

Patients with type 2 diabetes without history of ocular treatment were recruited from 2017 to 2018. The average and quadrant parafoveal vessel density (PVD) were obtained with a commercial SS-OCTA device (Triton, Topcon, Japan). The univariate and multivariate linear regression was used to analyse the correlation of PVD with diabetic retinopathy (DR), diabetic macular edema (DME), HbA1c, and other factors.

RESULTS

A total of 919 patients were included in the final statistical analysis. After adjusting for other confounding factors, the DR patients had significantly lower average PVD (β = - 1.062, 95% CI = - 1.424 to - 0.699, P < 0.001) in comparison with those without DR. In addition, the patients with mild DR or vision-threatening diabetic retinopathy (VTDR) also had significantly lower PVD (P < 0.001 for mild DR, and P = 0.008 for VTDR) compared with those without DR. Age and HbA1c were also significantly related to PVD measurements, as shown by multivariable linear regression. Participants with DME had a significantly lower average PVD and temporal PVD than those without DME (P < 0.05).

CONCLUSIONS

Reduced PVD was independently associated with more severe DR, older age, higher HbA1c level, and the presence of DME. These findings suggested that macular vessel alterations in DR warrant further evaluation in the longitudinal studies.

OCT Angiography Study of the Macula in Patients with Diabetic Macular Edema Treated with Intravitreal Aflibercept

Purpose: To compare foveal avascular zone density (FAZ) in the superficial (SCP) and deep (DCP) capillary plexus and vessel density (VD) in the macula in eyes with diabetic macular edema (DME) treated with intravitreal aflibercept.Methods: Patients with DME were imaged at baseline, and 30 days after the 1^st, 2^nd and 3^rd intravitreal aflibercept injection. Images were analyzed for the FAZ area in the SCP and DCP in each visit and VD.Results: Twenty eyes were enrolled. FAZ was 0.304 ± 0.131 mm² in the SCP and 0.738 ± 0.5836 mm² in the DCP at baseline. SCP FAZ was not significantly different whereas, FAZ in the DCP decreased (p = .035) after treatment. VD in the center was 20.62 ± 4.31 at baseline and decreased by 8% (p = .002). Parafoveal VD remained unchanged with treatment.Conclusion: DCP ischemia may improve after aflibercept treatment. Central macular vessel density was found to decrease post-treatment, but the clinical relevance needs further investigation.

Recent Advances of Computerized Graphical Methods for the Detection and Progress Assessment of Visual Distortion Caused by Macular Disorders

Recent advances of computerized graphical methods have received significant attention for detection and home monitoring of various visual distortions caused by macular disorders such as macular edema, central serous chorioretinopathy, and age-related macular degeneration. After a brief review of macular disorders and their conventional diagnostic methods, this paper reviews such graphical interface methods including computerized Amsler Grid, Preferential Hyperacuity Perimeter, and Three-dimensional Computer-automated Threshold Amsler Grid. Thereafter, the challenges of these computerized methods for accurate and rapid detection of macular disorders are discussed. The early detection and progress assessment of macular disorders can significantly enhance the required clinical procedure for the diagnosis and treatment of macular disorders.