Two-year analysis of changes in the optic nerve and retina following anti-VEGF treatments in diabetic macular edema patients

Relationship Between Macular Thickness and Visual Acuity in the Treatment of Diabetic Macular Edema With Anti-VEGF Therapy: Systematic Review

Purpose:

To examine the relationship between central macular thickness (CMT) measured by optical coherence tomography (OCT) and visual acuity (VA) in patients with center-involving diabetic macular edema (DME) receiving antivascular endothelial growth factor (anti-VEGF) treatment.

Methods:

Peer-reviewed articles from 2016 to 2020 reporting intravitreal injections of bevacizumab, ranibizumab, or aflibercept that provided data on pretreatment (baseline) and final retinal thickness (CMT) and visual acuity (VA) were identified. The relationship between relative changes was assessed via a linear random-effects regression model controlling for treatment group.

Results:

No significant association between the logarithm of the minimum angle of resolution (logMAR) VA and CMT was found in 41 eligible studies evaluating 2667 eyes. The observed effect estimate was a 0.12 increase (95% CI, −0.124 to 2.47) in logMAR VA per 100 µm reduction in CMT after treatment change. There were no significant differences in logMAR VA between the anti-VEGF treatment groups.

Conclusions:

There was no statistically significant relationship between the change in logMAR VA and change in CMT as well as no significant effect of the type of anti-VEGF treatment on the change in logMAR VA. Although OCT analysis, including measurements of CMT, will continue to be an integral part of the management of DME, further exploration is needed on additional anatomic factors that might contribute to visual outcomes.

Progress and Challenges of Anti-VEGF Agents and Their Sustained-Release Strategies for Retinal Angiogenesis

Currently, the treatment for ocular neovascular diseases, including diabetic macular edema (DME) and age-related macular degeneration (AMD), mainly involves repeated intravitreal injection of anti-vascular endothelial growth factor (VEGF) drugs. Although it can preserve vision, repeated injections are an invasive treatment modality, leading to serious complications and reducing patient adherence to treatment. To reduce the frequency of administration, prolong the time of drug action, and avoid repeated intravitreal injections, the combination of sustained-release materials with anti-VEGF drug therapy has become an emphasis in ophthalmology. In this review, we highlight the current state of anti-VEGF technology, its challenges, and the sustained-release strategies under investigation or being used in clinical practice. Both continuous release and considerable therapeutic effects can be achieved by encapsulating anti-VEGF drugs in sustained-release materials to minimize the number of intravitreal injections. At present, two sustained-release materials are being tested in clinical research, and although basic research shows the strong therapeutic application prospects of extended-release drugs, its challenges mainly involve the discrepancy between the release rates in vitro and the efficiency of the drugs in vivo. Briefly, sustained release of anti-VEGF agents is an advantageous strategy for treating retinal angiogenesis.

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.

BRAIN HEALTH ASSESSMENT IN MACULAR DEGENERATION PATIENTS UNDERGOING INTRAVITREAL ANTI-VASCULAR ENDOTHELIAL GROWTH FACTOR INJECTIONS (THE BHAM STUDY): An Interim Analysis

PURPOSE

After intravitreal injection, anti-vascular endothelial growth factor (VEGF) agents are found in the systemic circulation and can suppress systemic VEGF levels. Neuronal health and cognitive function in the central nervous system have been associated with normal physiological levels of VEGF expression. We wished to determine whether there was an association between cumulative anti-VEGF exposure and cognitive function.

METHODS

One hundred and seventy-five patients aged 65 to 85 with vision of at least 20/50 or better in one eye and a diagnosis of age-related macular degeneration took an iPad-based brain health assessment to determine their risk of mild cognitive impairment. The result for each patient was compared with the total number of anti-VEGF injections per individual patient. Patients were then stratified into groups with 0 injections (control), 1 to 9 injections, 10 to 20 injections, or greater than 20 injections.

RESULTS

The group of patients with more than 20 injections had a higher likelihood of mild cognitive impairment compared with the control group, with statistically significant worse mean Z-scores (P = 0.04).

CONCLUSION

Our study is the first to associate worsening cognitive health with higher cumulative anti-VEGF injections. This study was not designed to show a causal link, but does suggest that additional investigation is warranted.

[Anti-angiogenesis therapy of diabetic macular edema in patients with primary open-angle glaucoma]

Despite the high clinical effectiveness and widespread introduction of anti-angiogenesis (anti-VEGF) therapy into practice, its long-term effect on the development of structural changes in the treatment of primary open-angle glaucoma (POAG) patients with diabetic macular edema (DME) hasn't been studied sufficiently and so presents certain interest.

PURPOSE

To study the effect of anti-VEGF therapy on the structural and functional state of the retina and optic nerve in patients with DME and POAG.

MATERIAL AND METHODS

The study included 72 patients (132 eyes): the 1^st group - 22 patients (40 eyes) with stage I POAG and DME, the 2^nd group - 25 patients (46 eyes) with DME receiving anti-VEGF therapy. The 3^rd group (control) consisted of 25 patients (46 eyes) with stage I POAG. The observation period lasted 24 months. The average number of injections was 8.48±3.65. The indicators for evaluation were: visual acuity, tonometry, perimetry, optical coherence tomography (OCT) of the optic nerve and macular region.

RESULTS

By the end of the observation period, the increase in IOP in the groups was +0.82 (4.4%), 0.41 (2.4%), 0.65 (3.6%) mm Hg. In the group of comorbid patients, a small-scale increase trend of BCVA was noted: +0.05 (6.6%), a decrease in MD by -2.48 Db (92.1%), an increase in excavation volume by 0.16 (43.2%) mm³, decrease in the area of RA by 0.3 mm² (12.7%). A decrease in retinal nerve fibers layer (RNFL) thickness of 6.55 μm (7.8%), mainly the superior (9.2%), inferior (7.3%) and nasal sectors (7.9%). Loss of GCL+IPL 8.68 μm (12.7%) in the superior (19%), superonasal (20.2%) and inferonasal (20.7%) sectors.

CONCLUSION

The combined course of POAG and DME is accompanied by a decrease in the functional and structural parameters of the retina and optic nerve, and a higher rate of progression of glaucomatous optic neuropathy. Long-term results did not reveal a significant deterioration in the structural parameters of the optic disc and retina against the background of anti-VEGF therapy when comparing the study groups.

Dual-Acting Antiangiogenic Gene Therapy Reduces Inflammation and Regresses Neovascularization in Diabetic Mouse Retina

Intravitreal injections of anti-vascular endothelial growth factor drugs have become the gold standard treatment for diabetic retinopathy (DR). However, several patients are classified as non-responders or poor responders to treatment. Therefore, it is essential to study alternative target molecules. We have previously shown that the progression of DR in the Ins2^Akita mouse reflects the imbalance between pro- and anti-angiogenic molecules found in the human retina. We report, for the first time, the therapeutic potential of a dual-acting antiangiogenic non-viral gene therapy. We have used an expressing vector encoding both the pigment epithelium-derived factor gene and a short hairpin RNA (shRNA) targeted to the placental growth factor to restore the balance between these factors in the retina. Twenty-one days after a single subretinal injection, we observed a marked decrease in the inflammatory response in the neural retina and in the retinal pigment epithelium, together with reduced vascular retinal permeability in the treated diabetic mouse. These results were accompanied by the restoration of the retinal capillary network and regression of neovascularization, with significant improvement of DR hallmarks. Concomitant with the favorable therapeutic effects, this approach did not affect retinal ganglion cells. Hence our results provide evidence toward the use of this approach in DR treatment.