Microperimetric assessment of retinal sensitivity in eyes with diabetic macular edema from a phase 2 study of intravitreal aflibercept

Effectiveness of Mp-3 Microperimetric Biofeedback Fixation Training For Low Vision Rehabilitation in Patients Treated With Corticosteroid Ivt in Retinal Vein Occlusions

Background

The success of fixation training using microperimetric biofeedback (MP-3 MBFT) in the realm of visual rehabilitation for patients with central vision loss caused by macular pathologies is well established. This study aimed to assess the effectiveness and safety of visual rehabilitation with microperimetric biofeedback in consolidating the benefits obtained, with the goal of reducing the need for repeated intravitreal injections (IVT). Specifically, the focus is on the eyes of patients with central vision loss treated with slow-release corticosteroid IVT following retinal venous thrombosis (RVO), aiming to enhance and maintain postoperative efficacy.

Methods

This retrospective review involved the examination of 44 eyes affected by macular edema due to RVO associated with central vision loss. Patients were divided into two groups, with only one undergoing ten sessions of 10-minute visual rehabilitation with a microperimeter (MP-3 MBFT) after IVT over a period of 20 weeks.

Results

All the treated patients demonstrated good tolerance to the procedure, with no reported complications. A comparison of best-corrected visual acuity (BCVA), retinal sensitivity recorded with a microperimeter, and pre-IVT fixation stability revealed statistically significant improvements at the end of the first month after IVT. However, the treatment group continued to exhibit superior and more enduring results at four months post-IV.

Conclusion

The synergistic use of MP-3 MBFT rehabilitation after IVT with slow-release corticosteroids has proven particularly effective in improving BCVA and long-term fixation stability. This led to a significant reduction in the number of required IVTs, with no related adverse events. The authors argue that biofeedback utilization represents a noninvasive therapeutic option devoid of contraindications and easy to implement and that it positively contributes to the overall patient experience regarding quality of life in advanced stages of macular diseases.

Navigated direct photocoagulation with a 30-ms short-pulse laser for treating microaneurysms in diabetic macular edema exhibits a high closure rate

This study carried out direct photocoagulation for treating microaneurysms (MAs) in diabetic macular edema (DME) using a navigation laser system with a 30-ms pulse duration. The MA closure rate after 3 months was investigated using pre and postoperative fluorescein angiography images. MAs primarily inside the edematous area based on optical coherence tomography (OCT) maps were selected for treatment, and leaking MAs (n = 1151) were analyzed in 11 eyes (eight patients). The total MA closure rate was 90.1% (1034/1151), and the mean MA closure rate in each eye was 86.5 ± 8.4%. Mean central retinal thickness (CRT) decreased from 471.9 ± 73.0 μm to 420.0 ± 87.5 μm (P = 0.049), and there was a correlation between the MA closure rate and the CRT reduction rate (r = 0.63, P = 0.037). There was no difference in the MA closure rate depending on the degree of edema thickness based on a false-color topographic OCT map image. Direct photocoagulation for DME with a short pulse using the navigated photocoagulator resulted in a high MA closure rate in just 3 months and a corresponding improvement in retinal thickness. These findings encourage the use of a new therapeutic approach for DME.

Microperimetric analysis of diabetic macular edema after navigated direct photocoagulation with short-pulse laser for microaneurysms

BACKGROUND

Focal laser photocoagulation is an important treatment option for diabetic macular edema (DME). This study aimed to examine the retinal sensitivity (RS) and morphological changes at the coagulated site after direct photocoagulation of microaneurysms (MAs) in patients with DME using a navigated laser photocoagulator with a short-pulse duration of 30 ms.

METHODS

Images of early-phase fluorescein angiography were merged with images from the optical coherence tomography (OCT) map with 9 Early Treatment Diabetic Retinopathy Study grid circles, and MAs inside the edema area were selected for direct photocoagulation. The best-corrected visual acuity (BCVA), parameters of the OCT map including central retinal thickness and retinal thickness in edema range, central RS, and RS in the edema area were assessed at 1 and 3 months after the laser treatment. The RS points that overlapped with the laser spots were identified by merging the Navilas' digital treatment reports and the microperimetry images.

RESULTS

Seventeen eyes from 14 patients were studied. The mean retinal thickness in the edema range decreased at 3 months compared with pretreatment (P = 0.042), but the BCVA, central retinal thickness, central RS, and RS in the edema area remained unchanged. Overall, 32 of 400 sensitivity points overlapped with the laser-coagulated spots. The mean RS at these spots were 22.4 ± 5.3 dB at 1 month and 22.5 ± 4.8 dB at 3 months, with no significant change from the baseline of 22.7 ± 3.5 dB.

CONCLUSIONS

Retinal thickness improved in the coagulated edema area without a decrease in RS after direct photocoagulation of MAs with a short 30-ms pulse using Navilas. This promising therapeutic strategy for DME is effective and minimally invasive.

MACULAR ADD-ON INTRAOCULAR LENS SUCCESSFULLY RESTORES READING VISION IN EYES WITH END-STAGE DIABETIC MACULAR DISEASE

PURPOSE

To report the outcomes of macular add-on intraocular lens implantation in improving reading vision in patients with bilateral advanced diabetic maculopathy.

METHODS

In this retrospective study, a supplementary bifocal sulcus intraocular lens (Scharioth Macular Lens) was implanted in the better-seeing eye of five patients. Baseline-corrected distance vision, corrected near visual acuity, a preoperative simulation test, and multimodal imaging were collected. The primary outcome was the uncorrected near visual acuity at a working distance of 15 cm, at a 12-month follow-up.

RESULTS

Study patients included 3 cases of refractory subfoveal exudation and 2 cases of diabetic macular ischemia. A preoperative test to assess the potential gain in near vision showed an improvement of ≥2 paragraphs on the RADNER reading chart in all patients. At 12 months, median reading vision (corrected near visual acuity at 15 cm) significantly improved from 20/125 (range 20/50-20/200) preoperatively to uncorrected near visual acuity (at 15 cm) of 20/50 (range 20/40-20/80) (P = 0.042; Wilcoxon signed-ranks test). Distance vision remained unchanged in four patients. All patients were able to achieve the size of newsprint (20/50 Snellen equivalent), within the first 3 months.

CONCLUSION

The macular add-on intraocular lens improves reading vision in visually impaired patients due to end-stage diabetic macular disease.

Detecting Diabetic Retinal Neuropathy Using Fundus Perimetry

Fundus perimetry is a new technique for evaluating the light sense in the retina in a point-to-point manner. Light sense is fundamentally different from visual acuity, which measures the threshold for discriminating and perceiving two points or lines, called the minimum cognoscible. The quality of measurement of retinal sensitivity has dramatically increased in the last decade, and the use of fundus perimetry is now gaining popularity. The latest model of fundus perimetry, MP-3, can be used for a wide range of measurements and has an advanced eye tracking system. High background illumination enables accurate measurement of mesopic retail sensitivity. Recent investigations have shown that neuronal damage precedes vascular abnormalities in diabetic retinopathy. The loss of retinal function has also been reported prior to morphological changes in the retina. In this review, the importance of measuring retinal sensitivity to evaluate visual function in the early stages of diabetic retinopathy was discussed. The usefulness of retinal sensitivity as an outcome measure in clinical trials for treatment modalities is also presented. The importance of fundus perimetry is promising and should be considered by both diabetes researchers and clinical ophthalmologists.

Clinical Perspectives and Trends: Microperimetry as a trial endpoint in retinal disease

Endpoint development trials are underway across the spectrum of retinal disease. New validated endpoints are urgently required for the assessment of emerging gene therapies and in preparation for the arrival of novel therapeutics targeting early stages of common sight-threatening conditions such as age-related macular degeneration. Visual function measures are likely to be key candidates in this search. Over the last two decades, microperimetry has been used extensively to characterize functional vision in a wide range of retinal conditions, detecting subtle defects in retinal sensitivity that precede visual acuity loss and tracking disease progression over relatively short periods. Given these appealing features, microperimetry has already been adopted as an endpoint in interventional studies, including multicenter trials, on a modest scale. A review of its use to date shows a concurrent lack of consensus in test strategy and a wealth of innovative disease and treatment-specific metrics which may show promise as clinical trial endpoints. There are practical issues to consider, but these have not held back its popularity and it remains a widely used psychophysical test in research. Endpoint development trials will undoubtedly be key in understanding the validity of microperimetry as a clinical trial endpoint, but existing signs are promising.

Effects of Intravitreal Aflibercept on Retinal Function and Improvement of Macular Edema Associated With Diabetic Retinopathy

Purpose

To determine the effectiveness of intravitreal aflibercept (IVA) on the retinal function in eyes with diabetic macular edema (DME).

Methods

Twenty-five eyes of 25 patients with DME were treated with three consecutive monthly IVA injections. The retinal sensitivities (RS) within the central 10° were determined by microperimetry (MP). The central subfield macular thickness (CMT) was determined by optical coherence tomography, and the implicit times (IT) and amplitudes (Amp) of the flicker electroretinograms (ERGs) were determined from the ERGs elicited and recorded by the RETeval. The number of microaneurysms (MAs) was counted in the fundus photographs. The assessments were made before the IVA injections (pre-IVA) and one week after the IVA injections (post-IVA). The correlations between the reduction ratio of the MA numbers/CMT and RS/IT/Amp were evaluated.

Results

The mean RS improved from 19.9 ± 5.9 dB to 22.0 ± 5.8dB, the CMT decreased from 485.7 ± 90.6 µm to 376.9 ± 81.6 µm, and the number of MAs decreased from 49.6 ± 33.2 to 24.8 ± 18.1 after the IVA injection (all P < 0.01). The changes in the IT from 31.3 ± 3.3 ms to 31.5 ± 3.1 ms and the Amp from 12.2 ± 5.5 µV to 11.3 ± 6.1µV post-IVA were not significant. A significant correlation was found between the relative changes in the CMT and RS (r = −0.43; P = 0.02), the MAs and RS (r = −0.38; P = 0.03). No significant correlation was observed between the relative changes of the number of MAs/CMT and IT/Amp.

Conclusions

IVA can improve both central retinal function and anatomical conformation.

Translational Relevance

A new aspect of aflibercept will be useful for DME treatment.

Prospective study of morphologic and functional parameter changes post intravitreal therapy for macular edema

PURPOSE

Retinal sensitivity (RS) can be a valuable indicator of retinal function in response to intravitreal steroid or anti-VEGF treatment in the eyes with diabetic macular edema (DME), macular edema post retinal vein occlusion (RVO), or uveitis.

METHODS

This prospective longitudinal study included 68 patients (96 eyes) with macular edema (ME) secondary to diabetes mellitus (42 eyes), uveitis (36 eyes), or RVO (18 eyes). In addition to best corrected visual acuity (BCVA) and retinal thickness, Nidek MP1 microperimetry was used to quantify RS at baseline visit and to look at the mean difference (MD) at 3-6 months and 1-2 years post intravitreal therapy with corticosteroids or anti-VEGF.

RESULTS

There was a significant negative correlation between the central RS and BCVA (r = - 0.47, p < 0.001), including DME (r = - 0.42, p = 0.006) and uveitis (r = - 0.60, p < 0.001), but not RVO (r = - 0.37, p = 0.12). At 2-year follow-up, the overall CST was reduced from baseline (MD - 147 μm, 95% C.I - 192 to - 102, p < 0.001) with improved BCVA (MD - 0.12 LogMAR, 95% C.I - 0.23 to - 0.01, p = 0.01), but no improvement in the RS in any of the disorders. Both anti-VEFG and steroid groups showed significant improvement in CST at 2 years from baseline (MD - 101 μm, p = 0.001 and - 167 μm, p < 0.001, respectively) with only improvement in BCVA among anti-VEGF group (MD - 0.16 LogMAR, 95% C.I - 0.26 to - 0.07, p = 0.008).

CONCLUSION

The long-term follow-up of ME cases did not show a significant improvement in RS following treatment even with reduced macular thickness at 2-year follow-up.

How do we evaluate the role of focal/grid photocoagulation in the treatment of diabetic macular edema?

Vascular endothelial growth factor inhibitors (anti-VEGF) have consistently demonstrated efficacy and safety and changed both the aim and perspectives of diabetic macular edema (DME) treatment. Hence, the present and future role of focal/grid laser photocoagulation in DME treatment has been subjected to some debate. However, extensive insight into technical advances in novel laser systems, treatment protocols of anti-VEGF trials and the functional impact of modern focal/grid photocoagulation is needed to evaluate the present and future role of photocoagulation in DME treatment. Across a wide range of clinical trials laser therapy was required as adjunctive/rescue treatment in approximately 20-50% of patients receiving anti-VEGF monotherapy for centre involving DME. Further, a lower retreatment rate and a more stable reduction in retinal thickness have been demonstrated in more studies. However, lacking information on the laser systems used, their technical specifications and protocols of application often complicates direct comparison of results in anti-VEGF trials. Hence, this paper aimed to provide an overview of the currently available data relevant to the potential role of focal/grid laser photocoagulation in DME treatment including a thorough overview of the current most commonly used laser systems. Results with subthreshold diode micropulse laser photocoagulation are intriguing and may offer a valuable option as adjunctive therapy to anti-VEGF treatment. However, more well-designed studies on combination therapy are warranted to determine the full potential of modern retinal photocoagulation systems. In conclusion, current data suggest that focal/grid laser therapy should still be an option for consideration as adjunctive therapy in many patients.

Lymphatic Vascular Structures: A New Aspect in Proliferative Diabetic Retinopathy

Diabetic retinopathy (DR) is the most common diabetic microvascular complication and major cause of blindness in working-age adults. According to the level of microvascular degeneration and ischemic damage, DR is classified into non-proliferative DR (NPDR), and end-stage, proliferative DR (PDR). Despite advances in the disease etiology and pathogenesis, molecular understanding of end-stage PDR, characterized by ischemia- and inflammation-associated neovascularization and fibrosis, remains incomplete due to the limited availability of ideal clinical samples and experimental research models. Since a great portion of patients do not benefit from current treatments, improved therapies are essential. DR is known to be a complex and multifactorial disease featuring the interplay of microvascular, neurodegenerative, metabolic, genetic/epigenetic, immunological, and inflammation-related factors. Particularly, deeper knowledge on the mechanisms and pathophysiology of most advanced PDR is critical. Lymphatic-like vessel formation coupled with abnormal endothelial differentiation and progenitor cell involvement in the neovascularization associated with PDR are novel recent findings which hold potential for improved DR treatment. Understanding the underlying mechanisms of PDR pathogenesis is therefore crucial. To this goal, multidisciplinary approaches and new ex vivo models have been developed for a more comprehensive molecular, cellular and tissue-level understanding of the disease. This is the first step to gain the needed information on how PDR can be better evaluated, stratified, and treated.

The efficacy and safety of aflibercept and conbercept in diabetic macular edema

Diabetic macular edema (DME) has shown an increasing prevalence during the past years and is the leading cause of diabetic retinopathy blindness. Traditional treatment modalities include laser and corticosteroid therapy, which, however, either act through unclear mechanisms or cause cataracts and elevated intraocular pressure. In recent years, as the pathogenic role of VEGF in DME has been well-recognized, the intravitreal injection of anti-VEGF drugs has become the first-line treatment of DME due to their great efficacy in improving visual acuity and mitigating macular edema. Advantages have been shown for aflibercept and conbercept, the two recombinant decoy receptors that can bind VEGF with high specificity and affinity, in DME treatment in clinical trials conducted both worldwide and in People’s Republic of China. This review introduces the structural characteristics and molecular mechanisms of action of these two anti-VEGF drugs, and summarizes the clinical trials evaluating their efficacy and safety, with the hope to provide clues for designing optimal and personalized therapeutic regimens for DME patients.

Placental growth factor and its potential role in diabetic retinopathy and other ocular neovascular diseases

The role of vascular endothelial growth factor (VEGF), including in retinal vascular diseases, has been well studied, and pharmacological blockade of VEGF is the gold standard of treatment for neovascular age‐related macular degeneration, retinal vein occlusion and diabetic macular oedema. Placental growth factor (PGF, previously known as PlGF), a homologue of VEGF, is a multifunctional peptide associated with angiogenesis‐dependent pathologies in the eye and non‐ocular conditions. Animal studies using genetic modification and pharmacological treatment have demonstrated a mechanistic role for PGF in pathological angiogenesis. Inhibition decreases neovascularization and microvascular abnormalities across different models, including oxygen‐induced retinopathy, laser‐induced choroidal neovascularization and in diabetic mice exhibiting retinopathies. High levels of PGF have been found in the vitreous of patients with diabetic retinopathy. Despite these strong animal data, the exact role of PGF in pathological angiogenesis in retinal vascular diseases remains to be defined, and the benefits of PGF‐specific inhibition in humans with retinal neovascular diseases and macular oedema remain controversial. Comparative effectiveness research studies in patients with diabetic retinal disease have shown that treatment that inhibits both VEGF and PGF may provide superior outcomes in certain patients compared with treatment that inhibits only VEGF. This review summarizes current knowledge of PGF, including its relationship to VEGF and its role in pathological angiogenesis in retinal diseases, and identifies some key unanswered questions about PGF that can serve as a pathway for future basic, translational and clinical research.

Updates on the Clinical Trials in Diabetic Macular Edema

In this era of evidence-based medicine, significant progress has been made in the field of pharmacotherapeutics for the management of diabetic macular edema (DME). A. number of landmark clinical trials have provided strong evidence of the safety and efficacy of agents such as anti-vascular endothelial growth factors for the treatment of DME. Decades of clinical research, ranging from the early treatment of diabetic retinopathy study to the present-day randomized clinical trials (RCTs) testing novel agents, have shifted the goal of therapy from preventing vision loss to ensuring a maximum visual gain. Systematic study designs have provided robust data with an attempt to optimize the treatment regimens including the choice of the agent and timing of therapy. However, due to a number of challenges in the management of DME with approved agents, further studies are needed. For the purpose of this review, an extensive database search in English language was performed to identify prospective, RCTs testing pharmacological agents for DME. In order to acquaint the reader with the most relevant data from these clinical trials, this review focuses on pharmacological agents that are currently approved or have widespread applications in the management of DME. An update on clinical trials presently underway for DME has also been provided.

Aflibercept: A Review of Its Use in Diabetic Macular Oedema

Aflibercept (Eylea(®)) is an anti-vascular endothelial growth factor agent indicated for intravitreal use in the treatment of diabetic macular oedema. In patients with diabetic macular oedema, significantly greater improvements from baseline to week 52 in visual acuity were seen with intravitreal aflibercept versus macular laser photocoagulation in the phase III VISTA-DME and VIVID-DME trials, and versus intravitreal bevacizumab or ranibizumab in those with worse visual acuity at baseline (i.e. Early Treatment Diabetic Retinopathy Study letter score of <69) in the phase III PROTOCOL-T trial. Intravitreal aflibercept was generally well tolerated in patients with diabetic macular oedema. In conclusion, intravitreal aflibercept is an important new treatment for diabetic macular oedema.