Correlation Between The Changes Of Macular Structure And Visual Acuity In Patients With Type 2 Diabetes Mellitus

Objective: To study the area of foveal avascular zone(FAZ),central foveal thickness(CFT),the thickness of the macular ganglion cell/inner plexiform layer(m GCIPL)and the best-corrected visual acuity(BCVA)in type 2 diabetic mellitus(DM)patients with different fundus lesions.To explore the correlation between the parameters.Methods:Prospective study.83 eyes of 51 patients with type 2 DM were enrolled in the study group and grouped according to the DR international clinical staging criteria.Non diabetic retinopathy group(NDR group,n=31),non-proliferative diabetic retinopathy group(NPDR group,n=52).Age matched healthy eyes were selected as the control group(control group,n=13).All subjects underwent medical history collection,intraocular pressure,optometry,BCVA,slit lamp,and ophthalmoscopy.Subjects underwent color fundus photography,OCT and OCTA examination after full mydriasis.OCT was used to measure the thickness of CFT and m GCIPL.OCTA was applied to obtain 4 layers of blood flow density scan images in macular area of 3mm*3mm size.The superficial FAZ area was measured by photoshop software.The BCVA was converted to the minimum resolution angle Log MAR record when doing statistical.The differences of BCVA,CFT,m GCIPL and superficial FAZ in each group were statistically analyzed,and to explore the correlation between the parameters.Results:I.Comparison of control group,NDR group and NPDR group The average area of superficial FAZ in the control group,NDR group and NPDR group were 0.314±0.103 mm2,0.349±0.102 mm2,0.416±0.148 mm2,respectively.The average area of superficial FAZ was NPDR group > control group(p=0.012),NPDR group>NDR group(p=0.024),the difference was statistically significant.There was no significant difference in the average area of superficial FAZ between the control group and the NDR group(p=0.414).The average area of the superficial FAZ gradually expanded with the progress of the disease(r=0.232,p=0.023).The mean Log MAR BCVA of the control group,NDR group and NPDR group were0.015±0.038,0.029±0.059,and 0.129±0.133,respectively.The mean Log MAR BCVA NPDR group> control group(p=0),NPDR group>NDR group(p=0.001),the difference was statistically significant.There was no significant difference in mean Log MAR BCVA between the control group and the NDR group(p=0.695).The mean Log MAR BCVA increased with the progression of the disease(r = 0.417,p = 0).The mean CFT of the control group,NDR group and NPDR group were247.46±13.35?m,244.13±25.09?m and 263.12±24.96?m,respectively.The mean CFT NPDR group> control group(p=0.037),NPDR group>NDR group(p=0.001),the difference was statistically significant.There was no significant difference in mean CFT between the control group and the NDR group(p=0.673).The mean m GCIPL thickness of the control group,NDR group and NPDR group were 89.00±4.98?m,86.06±4.43?m and 82.61±14.32?m,respectively.There was no significant difference in mean m GCIPL thickness between the three groups(p=0.123).The mean minimum m GCIPL thickness of the control group,NDR group and NPDR group were 84.85 ±3.18?m,80.68± 5.39?m and 71.19±19.94?m,respectively.The mean minimum m GCIPL thickness NPDR group<control group(p=0.004),NPDR group<NDR group(p=0.007),the difference was statistically significant.There was no significant difference in the mean minimum m GCIPL thickness between the control group and the NDR group(p=0.406).The average minimum m GCIPL thickness gradually thinner as the disease progressed(r=-0.356,p=0).II.Correlation analysis The superficial FAZ area was positively correlated with log MAR BCVA,r=0.335,p=0.001;the superficial FAZ average area was negatively correlated with CFT,r=-0.262,p=0.010;the superficial FAZ area was negatively correlated with the minimum m GCIPL thickness,r =-0.213,p=0.037;log MAR BCVA was negatively correlated with mean m GCIPL thickness,r=-0.348,p=0.001;log MAR BCVA was negatively correlated with minimum m GCIPL thickness,r=-0.416,p=0.Conclusion:1.With the progression of the type 2 DM,the superficial FAZ area gradually expands,the minimum m GCIPL thickness and the Log MAR BCVA gradually increases.2.There is a certain correlation between superficial FAZ,CFT,m GCIPL thickness and visual acuity.3.OCTA is a relatively new non-invasive method to study FAZ.FAZ changes can be observed before the presence of clinical DR.OCTA can be used as an important means of fundus screening and monitoring disease progression in DM.