Anti-VEGF and steroid combination therapy relative to anti-VEGF mono therapy for the treatment of refractory DME: A systematic review of efficacy and meta-analysis of safety

Effects of vitrectomy combined with internal limiting membrane peeling in patients with diabetic macular edema

BACKGROUND

Diabetic macular edema (DME), a chronic microvascular complication of diabetes, is a leading cause of visual impairment and blindness. Pars plana vitrectomy (PPV) can restore the normal macular structure and reduce macular edema, whereas internal limiting membrane (ILM) peeling is used to treat tractional macular diseases. Despite the advantages, there is limited research on the combined effects of PPV with ILM peeling.

AIM

To observe the effects of PPV combined with ILM peeling on postoperative central macular thickness (CMT), best-corrected visual acuity (BCVA), cystoid macular edema (CME) volume, and complications in patients with DME.

METHODS

Eighty-one patients (92 eyes) diagnosed with DME at the Beijing Shanqu Liangxiang Hospital between January and December 2022 were randomly divided to undergo PPV alone (control group: 41 patients, 47 eyes) or PPV + ILM peeling (stripping group: 40 patients, 45 eyes); a single surgeon performed all surgeries. The two groups were compared preoperatively and 1 and 3 months postoperatively.

RESULTS

Preoperatively, both groups had comparable values of CMT, BCVA, and CME volume (P > 0.05). After surgery (both 1 and 3 months), both groups showed significant reductions in CMT, BCVA, and CME volume compared to preoperative levels, with the stripping group showing more significant reductions compared to the control group (P < 0.05). Further repeated-measures ANOVA analysis for within-group differences revealed significant effects of group and time, and interaction effects for CMT, BCVA, and CME volume (P < 0.05). There were no significant differences in the incidence of complications between the groups (retinal detachment: control = 2, stripping = 1; endophthalmitis: Control = 4, stripping = 1; no cases of secondary glaucoma or macular holes; χ² = 0.296, P = 0.587).

CONCLUSION

PPV with ILM peeling can significantly improve the visual acuity of patients with DME, reduce CMT, and improve CME with fewer complications.

Anti-angiogenic and antioxidant effects of axitinib in human retinal endothelial cells: implications in diabetic retinopathy

Diabetic retinopathy is a secondary microvascular complication of diabetes mellitus. This disease progresses from two stages, non-proliferative and proliferative diabetic retinopathy, the latter characterized by retinal abnormal angiogenesis. Pharmacological management of retinal angiogenesis employs expensive and invasive intravitreal injections of biologic drugs (anti-vascular endothelial growth factor agents). To search small molecules able to act as anti-angiogenic agents, we focused our study on axitinib, which is a tyrosine kinase inhibitor and represents the second line treatment for renal cell carcinoma. Axitinib is an inhibitor of vascular endothelial growth factor receptors, and among the others tyrosine kinase inhibitors (sunitinib and sorafenib) is the most selective towards vascular endothelial growth factor receptors 1 and 2. Besides the well-known anti-angiogenic and immune-modulatory functions, we hereby explored the polypharmacological profile of axitinib, through a bioinformatic/molecular modeling approach and in vitro models of diabetic retinopathy. We showed the anti-angiogenic activity of axitinib in two different in vitro models of diabetic retinopathy, by challenging retinal endothelial cells with high glucose concentration (fluctuating and non-fluctuating). We found that axitinib, along with inhibition of vascular endothelial growth factor receptors 1 (1.82 ± 0.10; 0.54 ± 0.13, phosphorylated protein levels in fluctuating high glucose vs . axitinib 1 µM, respectively) and vascular endothelial growth factor receptors 2 (2.38 ± 0.21; 0.98 ± 0.20, phosphorylated protein levels in fluctuating high glucose vs . axitinib 1 µM, respectively), was able to significantly reduce (p < 0.05) the expression of Nrf2 (1.43 ± 0.04; 0.85 ± 0.01, protein levels in fluctuating high glucose vs . axitinib 1 µM, respectively) in retinal endothelial cells exposed to high glucose, through predicted Keap1 interaction and activation of melanocortin receptor 1. Furthermore, axitinib treatment significantly (p < 0.05) decreased reactive oxygen species production (0.90 ± 0.10; 0.44 ± 0.06, fluorescence units in high glucose vs . axitinib 1 µM, respectively) and inhibited ERK pathway (1.64 ± 0.09; 0.73 ± 0.06, phosphorylated protein levels in fluctuating high glucose vs . axitinib 1 µM, respectively) in HRECs exposed to high glucose. The obtained results about the emerging polypharmacological profile support the hypothesis that axitinib could be a valid candidate to handle diabetic retinopathy, with ancillary mechanisms of action.

Correlation between Topographic Vessel Density and Retinal Thickness Changes in Patients with Diabetic Macular Edema Treated with Anti-VEGF Therapy: Is It a Suitable OCTA Biomarker?

The objective of this study was to determine the correlation between topographic vessel density (VD) and retinal thickness (RT) reductions induced by vascular endothelial growth factor inhibitors (anti-VEGF) in patients with diabetic macular edema (DME) using optical coherence tomography angiography (OCTA). This was a prospective, interventional case series. VD and RT measurements were separately taken in four parafoveal subfields at baseline and after six months of treatment. This correlation was statistically assessed using Spearman's rho correlation coefficient after adjustment for multiple comparisons. The study included a total of 48 eyes in the final analysis. Mean VD decreased from baseline to month 6 (from 45.2 (±3.5) to 44.6% (±3.2) in the superficial capillary plexus and from 50 (±3.3) to 49% (±3.9) in the deep capillary plexus). Statistically significant reductions in RT were observed in all ETDRS sectors (p < 0.0001). No significant association was found between RT and VD, even when analyzing responders and non-responders separately. After six months of anti-VEGF treatment, no significant correlation was observed between the topographic VD and RT values. These findings suggest that reductions in VD values may not solely result from a reduction in microaneurysms, also being affected by the repositioning of displaced vessels due to edema and a reduction in their caliber. Therefore, VD changes may not be a suitable indirect OCTA biomarker of microaneurysm turnover and treatment response.