The Correlation Between The Structure Of Outer Retina And The Recovery Of Visual Function Before And After Anti-VEGF Treatment Of DME

Objective:To evaluate the efficacy of anti-VEGF therapy in patients with diabetic macular edema(DME)by multifocal electroretinogram(mf-ERG)and Optical coherence tomography coherence tomography(OCT),the relationship between the changes of mf-ERG waveforms and the structural changes of the outer retina in OCT was studied.The value of mf-ERG combined with OCT in the evaluation and prediction of visual function recovery after anti-VEGF treatment in DME patients was further discussed.Methods:Retrospective collection was performed from March 2022 to December 2022 in the first People’s Hospital of Yunnan Province,where DME was diagnosed and performed monthly,a total of 28 patients(46 eyes)were treated with anti-VEGF(3+PRN)intravitreal injection for 3 months.Patients were followed up at the time of diagnosis and the day before treatment each month.Follow-up data included 1.Best corrected visual acuity(BCVA)2.OCT related indexes include(1)central retinal thickness(CRT).(2)retinal volume(RV)(1RV,3RV)in the 1mm and 3mm area around the macular,(3)the structural damage of outer retinal layers(ORLs).these include the disruption of the structure and integrity of the sub-layers between the external limiting membrane(ELM)and Retinal pigment epithelium(RPE)layers,as well as the rupture length of ELM and ellipsoid zone(EZ).3.The parameters of mf-ERG include three concentric rings(R1 ring,R2 ring,R3 ring)p1 wave amplitude density,P1 wave latency and N1 wave latency.BCVA,1RV,3RV,the rupture length of ELM,EZ and the waveform characteristics of mf-ERG were analyzed at four time points,and the correlation of BCVA,OCT,mf-ERG was analyzed.According to the structural disorder and integrity of ORLs,they were divided into ORLs failure group(ORLs structural fracture,deletion,abnormal reflectivity)and ORLs integrity group According to RPE disturbance and integrity,the ORLs integrity group was further divided into RPE failure group and RPE integrity group.The difference of the recovery of mf-ERG waveform between the last follow-up and the pre-treatment was analyzed.Data were analyzed using SPSS26.0,which was considered statistically significant when P<0.05.Results:After 3 times of intravitreal injection of anti-VEGF drugs,BCVA in 33 eyes(71.7%)increased by at least 1 row on the standard log visual acuity chart.In OCT,CRT decreased significantly(P<0.001),1RV and 3RV decreased significantly(P<0.05),while ELM and EZ had no significant difference(P>0.05).Of 36 eyes with ORLs destruction,12 eyes(33.3%)had no BCVA response after treatment.In mf-ERG related indexes,the latencies of N1 in each ring decreased,the latencies of P1 wave and amplitude density of P1 wave in R1 and R2 rings were significantly decreased(p<0.05).In correlation analysis,BCVA was negatively correlated with CRT(P<0.05),CRT and 1RV were positively correlated with N1 latency in R1 and R2 rings,and negatively correlated with P1 amplitude density in R1 and R2 rings(P<0.05),3RV was positively correlated with N1 wave latency in each ring(P<0.05),ELM fracture length was not significantly correlated with mf-ERG waveform(P>0.05),EZ fracture length was positively correlated with N1 wave latency in each ring(P>0.05),it was positively correlated with P1 wave latency in R1 ring(P<0.05).Multiple regression analysis showed that the length of EZ fracture was correlated with the latencies of N1 wave in R2 ring(P<0.05).There was significant difference in the recovery of P1 amplitude density of R3 ring between the ORLs damaged group and the intact group(P<0.05),and there was significant difference in the recovery of P1 amplitude density of R1 ring between the RPE damaged group and the intact group(P<0.05).BCVA was negatively correlated with the latencies of N1 waves in R1 and R2 rings,and positively correlated with the amplitude densities of P1 waves in each ring(P<0.05).Conclusions:The results suggested that after 3 times of intravitreal injection of anti-VEGF,the decrease of CRT and RV was the most obvious,but both of them could not reflect the recovery of visual function.The structural changes of the outer retina are closely related to the changes of visual function.The abnormality of ORLs indicates the poor recovery of visual function in DME eyes.The change of the length of EZ rupture can predict the recovery of visual function.mf-ERG can provide more objective and comprehensive information of therapeutic effect and visual function recovery for DME patients after anti-VEGF treatment.