AIM: To observe the changes of retina superficial capillary plexus densities and aqueous humor factors in patients with diabetic macular edema(DME)before and after conbercept injection, and to explore the effect of conbercept on macular microcirculation in DME patients.

METHODS: A prospective case-control study was conducted. Totally 11 eyes of 10 patients diagnosed as DME in the Ophthalmology Department of the First Affiliated Hospital of Hainan Medical University from December 2019 to December 2020 were collected as DME group, 15 cataract patients without systemic basic diseases and fundus oculi diseases were collected as cataract group, and 20 age-and sex-matched healthy people with normal vision were collected as control group. All patients in DME group were treated by intravitreal injection of conbercept once a month for a total of 6 times. The retinal perfusion densities of the superficial capillary plexus(PSCP), retinal vessel densities of the superficial capillary plexus(VSCP), foveal avascular zone(FAZ), central macular thickness(CMT)and best corrected visual acuity(BCVA)were compared between the control group and DME patients before operation. The aqueous humor factors in cataract group and DME group were measured by multiplex flow immunoassay. The differences of aqueous humor factors in cataract group and DME group were compared. The changes of VSCP, PSCP, FAZ, CMT, BCVA and factors of aqueous humor in DME group after 6 conbercept injections were compared.

RESULTS: There were significant differences in PSCP, VSCP, FAZ area, BCVA and CMT between DME group and control group before operation(P<0.01); there were significant differences in angiopoietin-like protein 4(ANGPTL4), vascular endothelial growth factor(VEGF), interleukin-6(IL-6), interleukin-8(IL-8)in aqueous humor of DME group and cataract group before operation(P<0.001); PCSP and BCVA were increased and CMT were decreased in DME group after continuous conbercept injection for 6mo(all P<0.05); the concentrations of ANGPTL4, VEGF and IL-6 in aqueous humor of DME group decreased significantly(all P<0.05); patients injected with 1mo conbercept in the DME group had the most obvious improvement of BCVA and PSCP as well as the most obvious decline of CMT; while the ANGPTL4, VEGF and IL-6 in aqueous humor concentration had the most obvious decrease when they were injected with 1mo conbercept; VEGF in aqueous humor was positively correlated with the absolute value of CMT.

CONCLUSION: Conbercept injection in DME patients can improve retinal ischemia, reduce the concentration of VEGF and related factors in aqueous humor, effectively increase BCVA and relieve macular edema.