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

Abstract

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.

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

“…28 Other studies have used OCTA to evaluate the effect of intravitreal injections of anti-VEGF agents on the FAZ size and VD measurements in the macula of patients with DME and yielded conflicting results, but these studies did not separately compare changes in responders and nonresponders. 17,20,[30][31][32][33][34] In the current study, we found a significant increase in the FAZ area in eyes that showed a reduction in CMT after three IVB injections, compared with those that did not respond to treatment (Supplementary Table S1). The differential change in vascularity between eyes that showed an early treatment response, versus those that did not, could be a cause or consequence of the different anatomical response of each group, which calls for further study in a larger number of eyes.…”

OCT-Angiography Changes in Patients with Diabetic Macular Edema Treated with Intravitreal Dexamethasone Implant

“…There are several studies that analyze the macular perfusion changes using OCTA in patients with DME treated with anti-VEGF drugs with inconclusive results. [15][16][17] On the other hand, there is evidence suggesting qualitative changes in both the SCP and DCP in DME patients treated with DEX implant. 18,19 However, no quantitative changes in OCTA measures have been found.…”

Microvascular Changes After Conbercept Intravitreal Injection of PDR With or Without Center-Involved Diabetic Macular Edema Analyzed by OCTA

“…In addition, in previous research, anti-VEGF drugs, such as bevacizumab, ranibizumab, aflibercept, and conbercept were effective for DME ( 14 , 29 ). However, there has been controversy about whether the macular perfusion will get better or worse after anti-VEGF treatment ( 15 , 22 – 24 , 30 ). Zhao et al considered that there were no significant changes of macular and papillary VD after either the panretinal photocoagulation or intravitreal conbercept treatment ( 23 ).…”

“…It has been produced by the expression system of Chinese hamster ovary (CHO) cells ( 13 , 14 ). Studies proved the efficacy and safety of conbercept injections for the treatment of DME and PDR ( 15 , 16 ).…”

“…Optical coherence tomography angiography (OCTA) is a newly developed technology of fundus angiography, which is used to stratify the vessels of the retina and choroid, and has become an important instrument for the diagnosis and treatment of diabetic retinopathy ( 2 , 22 ). Thus, OCTA can be used to observe the therapeutic effect of anti-VEGF drugs more precisely ( 10 , 11 , 15 , 23 ). A few prior studies compared the effect of conbercept on DME by OCTA, and the results were controversial ( 22 – 24 ).…”