Microcirculation Status In Macular Area Of Normal Tension Glaucoma And Its Correlation With Microperimetry

Objective: Combination of optical coherence tomography angiography(OCTA)and Microperimetry to investigate the changes of macular superficial retinal vessel density,retinal sensitivity and fixation rate in patients with normal tension glaucoma(NTG),and to explore the correlation between macular microcirculation status and microperimetry examination characteristics in the macular area of normal tension glaucoma.Methods: A total of 17 NTG patients(30 eyes)who were treated in the Department of Ophthalmology of the First Affiliated Hospital of Nanchang University from May 2021 to December 2022 were collected as the NTG group,and were divided into 3 groups of mild,moderate and severe according to the severity of the disease,with 7 eyes,14 eyes,and 9 eyes,respectively.During the same period,13 cases and 23 eyes of healthy physical examiners matched by age and sex were selected as the control group.Using OCTA to scan the macular area,the superficial retinal vascular density(VD)and perfusion density(PD)were obtained,and the automatic analysis system of the instrument divided the scanning range into 2 rings and 5 regions according to ETDRS,including the central ring and the outer ring,and the outer ring was further divided into four regions: superior,inferior,nasal and temporal,and collected the VD and PD of each region and the overall average.The Microperimetry(MP-3)was used to measure retinal sensitivity(RS)and 2° and 4° fixation rate(P1,P2)in the macular area.According to the OCTA zoning method,the corresponding microperimetry fundus images were divided into five parts: central,superior,inferior,nasal and temporal,and the average RS of each area and the whole were recorded.The differences of OCTA parameters and Microperimetry MP-3 parameters were compared between the groups,and the correlation between OCTA parameters and Microperimetry MP-3 parameters in NTG patients was analyzed.Results: Except for the central and nasal sides of the macula,there were no significant differences in VD and PD between the control group and the mild NTG group,and the remaining regions and the overall mean VD and PD showed a gradual downward trend between the control group and the mild,moderate and severe NTG groups.Compared with the control group,the RS of the mild NTG group was lower in the inferior and temporal regions of the macular area,but there was no significant difference in the central,superior and nasal regions of the macular area and the overall average RS between the two groups.The mean RS of each region and the whole macular area decreased with the aggravation of NTG stage,that is,the mild NTG group was higher than the moderate NTG group,and the moderate NTG group was higher than the severe NTG group.In the NTG group,VD was positively and significantly correlated with RS and PD was positively correlated with RS in all regions of the macular area and in the overall average.In NTG group,VD,PD and RS in macular area were positively correlated regionally with P2,while there was no significant correlation between VD,PD and RS in macular area and P1.Conclusion: In mild to moderate NTG patients,the vascular microcirculation and visual function in macular area were impaired to a certain extent,and gradually decreased with the disease stages.In NTG patients,macular vascular microcirculation was well correlated with retinal sensitivity.OCTA combined with microperimetry can help to evaluate the changes of macular microcirculation and visual function in patients with NTG,which may provide an important means for early diagnosis and assessment of disease progression in patients with NTG.