| Objective:The choroidal thickness of patients with different degrees of myopia was automatically detected by SS-OCT.To analyze the relationship between subfoveal choroidal thickness(SFCT),choroidal thickness(CHT),peripapillary choroidal thickness(PCT)and gender,age,spherical equivalent refraction(SER)and axial length(AL).To observe the changes of choroidal thickness in different regions under different diopters and axial length,and understand its correlation,hoping to provide evaluation parameters for the degree of relevant pathological changes for clinical myopia progression.Methods:A total of 258 patients with different degrees of myopia and emmetropia were enrolled in the refractive clinic of our hospital from September 2020 to May 2021.The subjects were grouped according to gender,age,spherical equivalent refraction(SER),and axial length(AL).Group A: the subjects were divided into A1 and A2 according to the gender of the patients.Group A1 was male,group A2 was female.Group B: the subjects were divided into group B1(age<21years),group B2(21years-30 years),group B3(31 years-40 years)and group B4(40 years<age).Group C: the subjects were divided into 6 groups group according to the equivalent spherical power of the patients.Group C1(-0.50D<SER≤ +0.75D);Group C2(-3.00D<SER≤-0.50D);Group C3(-6.00D<SER≤-3.00D);Group C4(-9.00D<SER≤-6.00D);Group C5(-12.0D <SER≤-9.0D);Group C6(SER≤-12.0D).Group D: subjects were divided into groups according to the axial length of patients.Group D1(22mm≤AL < 24mm),Group D2(24mm≤AL < 26mm),Group D3(26mm≤AL < 28mm)and Group D4(28mm≤AL).Swept-source coherence tomography(SS-COT)was used to scan the subfoveal choroidal thickness(SFCT),the choroidal thickness around the macula(Ch T)and the choroidal thickness around the optic papilla(PCT).Each scan of the macula region was divided into three concentric circles,a central circle with a diameter of 1mm,an inner circle with a diameter of3 mm and an outer circle with a diameter of 6mm.The inner ring(the area between the central circle and the inner circle)and the outer ring(the area between the inner circle and the outer circle)are divided into 8 areas according to four quadrants(upper,lower,nasal and temporal).The scanning of the optic papilla takes the optic papilla as the center and makes a circle with a radius of 3.4mm.This area was divided into 4quadrants according to the upper,lower,nasal and temporal sides,or 12 regions according to the 12 o’clock direction.The relationships between SFCT,Ch T,PCT and gender,age,SER and AL in each group were compared and analyzed.SPSS23.0 software was used to analyze the data.Shapiro-wilk test,analysis of variance(ANOVA),LSD test,nonparametric test(Kruaskalwillis),X2 test and Pearson test were used to analyze the relationship between subfoveal choroidal thickness(SFCT),choroidal thickness around macular area(Ch T),peripapillary choroidal thickness(PCT)and gender,age,spherical equivalent refraction(SER)and axal length(AL).In this study,P≤0.05 indicates that the difference is statistically significant.Results:1.The average of subfoveal choroidal thickness(SFCT)was 211.72±85.47μm,which had no significant difference with age and gender(P>0.05).With the increase of ocular axis and the negative degree of spherical equivalent refraction,SFCT decreased gradually,and there was a significant statistical difference P=0.000(P < 0.05).SFCT was a positively correlated with spherical spherical equivalent refraction(SER).For every 1D increase in SER,SFCT increased by 11.86μm.The linear regression equation is SFCT=278.167+11.862 × SE(P=0.000).SFCT was negatively correlated with AL.For every 1mm increase in AL,SFCT decreased by 28.95μm.The linear regression equation SFCT=955.774-28.953×AL(P=0.000).2.There were differences in choroidal thickness in different macular regions:(1)There were differences in the choroidal thickness in different regions of the macular in different spherical equivalent power groups,and with the decrease of spherical equivalent power,the overall choroidal thickness in the macular region became thinner,but the changes in each region were uneven: the thickest I1 Ch T in group C1 was 308.09±72.07μm;the thickest temporal T1 Ch T in group C2 was 263.09±68.33μm;the thickest temporal t2 cht was found in group C3,C4,C5 and C6,with values of 239.76 ± 53.65μm,196.98 ± 55.23μm,191.66 ±58.95μm and 148.26 ± 60.56μm respectively.The Ch T in nasal N2 was the thinnest in all groups,including 238.74 ±72.46μm in group C1,180.78 ±64.71μm in group C2,144.72 ±54.96μm in group C3,114.33±48.00μm in group C4,104.02 ±54.95μm in group C5 and 70.57±24.94μm in group C6.The difference between each group was statistically significant(F=160.94,P=0.000,P<0.05).(2)There were differences in choroidal thickness in different regions of the macular in different axial length groups,and with the increase of axial length,the overall choroidal thickness in the macular region became thinner,but the changes in each region were uneven: the thickest I1 cht under group D1 was 299.96 ± 74.52μm;group D2 and D4 had the thickest temporal T2 CHT,which were 246.07 ± 61.74μm and 161.63 ±69.83μm respectively;the maximum thickness of S2 CTH above group D3 is 203.03 ± 60.53μm.However,all groups showed the thinnest CHT at the nasal N2,including 230.36 ± 76.59μm in group D1,159.25 ±58.54μm in group D2,109.64 ± 51.80μm in group D3 and 73.67 ±29.20μm in group D4.The difference between each group was statistically significant(F=169.114,P=0.000,P<0.05).3.There were differences in choroidal thickness(PCT)in different areas around the optic papilla:(1)There were differences in the thickness of the choroid around the optic disc between the different spherical equivalent power groups,and with the decrease of the spherical equivalent power,the overall choroidal thickness around the optic disc became thinner,but the changes in each area were uneven: PCT above the optic papilla was the thickest in all groups.They were 168.89±66.20μm in group C1,161.33±58.20μm in group C2,149.98±44.56μm in group C3,149.98±44.56μm in group C4,128.93±43.03μm in group C5 and 117.04±59.02μm in group C6.But the thinnest part was different.In group C1 and C2,the PCT under the optic papilla is the thinnest,with values 149.60±58.33μm and 130.67±49.89μm respectively;while group C3,C4,C5 and C6,all had the thinnest PCT on the temporal side of the optic papilla,with values of 114.16 ± 43.72μm,94.50 ± 43.98 μm,79.95 ± 35.58μm and 62.35 ± 25.67μm respectively.There were differences in choroidal thickness(PCT)around the optic papilla at different time points: the thickest parts of PCT in group C1 and C2 were 11 o’clock and 1 o’clock respectively,while the thinnest part of PCT in both groups was 6 o’clock.The thickest position of PCT in group C3,C4,C5 and C6 was 12 points.The thinnest PCT was 9 o’clock except for 8 o’clock in group C3.The difference between each group was statistically significant(F=96.91,P=0.000,P<0.05).(2)There were differences in the thickness of the choroid around the optic disc between different axial length groups,and with the increase of the axial length,the overall choroidal thickness around the optic disc became thinner,but the changes in each area were uneven: the average choroidal thickness above the optic papilla was the thickest in all groups.169.20 ± 56.80 μm in group D1,156.38 ± 55.85 μm in group D2,132.26± 46.55 μm in group D3 and 117.54 ± 55.14 μm in group D4.But the thinnest part was different.The average choroidal thickness under the optic papilla was the thinnest in group D1 and D2;The average choroidal thickness of the temporal side of the optic papilla was the thinnest in group D3 and D4.After grouping according to the length of ocular axis,the choroidal thickness of each hour area around the optic papilla was compared: the average choroidal thickness of group D1,D2,D3 and D4 was 12 points.The thinnest part of the average choroidal thickness is different.The orientation of group D1 and D2 was 6 points,that of D3 was 9 points,and that of D4 was 8 points.The difference between each group was statistically significant(F=12.377,P=0.000,P<0.05).Conclusion:1.There was no significant statistical difference between subfoveal choroidal thickness and age and gender,but it was positively correlated with spherical equivalent refraction and negatively correlated with axial length.2.The choroidal thickness in each area of macula varies unevenly in different diopter arrays and axial length groups.With the deepening of myopia,the thickest part of choroidal thickness in macula turns from below macula to temporal side of macula,but the thinnest part was still nasal side of macula area.3.The choroidal thickness around the optic disc varies unevenly in different diopter arrays and axial length groups.With the deepening of myopia,the thinnest part of the choroidal thickness around the optic papilla changes from below the optic papilla to the temporal side of the optic papilla,but the thickest part was still above the optic papilla.4.SFCT,CHT and PCT can be used as the evaluation parameters of the degree of pathological changes related to the progression of myopia. |
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