Analysis Of Optic Disc Characteristics In Different Degrees Of Myopia And High Myopia Combined With POAG By SS-OCT

Objective:To detect the optic disc characteristics of different degrees of myopia and high myopia with POAG by SS-OCT,so as to clarify the optic disc structure changes of primary open-angle glaucoma and high myopia and expect to provide early diagnosis basis for myopic cases with primary open angle glaucoma.Methods:Cross-sectional study.(1)Patients were selected from the refractive department of Changsha Aier Ophthalmology Hospital from July 2021 to November2021.According to the axial length(AL)and spherical equivalent degree(SE),the patients were divided into the following four groups:mild myopia group:22<AL1≤24 mm,-3D≤SE<0.5D;moderate myopia group:24<AL2≤26 mm,-6D≤SE<-3D;high myopia group:26<AL3≤28 mm,-12D≤SE<-6D;ultra-high myopia group:28<AL4≤30 mm,SE<-12D.(2)Patients with primary open angle glaucoma(POAG)with high myopia(HM),mild myopia and high myopia were selected from November 2021 to February 2022 in the department of glaucoma and refraction of Changsha Aier Ophthalmology Hospital.They were divided into three groups:POAG+HM group:26<AL≤30 mm,-6D<SE≤-12D;HM group:26<AL≤30 mm,-6D<SE≤-12D;mild myopia group:22<AL≤24 mm,-0.5D≤SE≤-3D(3)SS-OCT(SS-OCT Topcon,IMAGE net 6 V version 1.28.17642)was used to obtain OCT images of optic disc(4.5mmx4.5mm)and macular(6mmx6mm)and synchronous fundus photography(45°color fundus photography centered on optic disc)for all patients.The thickness of optic disc retinal nerve fiber layer(RNFL),macular ganglion cell complex(GCC)and choroid thickness(Ch T)were obtained by SS-OCT automatically.The tilt ratio and rotation of optic disc and the area ofβ-peripapillary chorioretinal atrophy(β-PPCA)were manually delineated and measured by Image-Pro Plus(Image Pro Plus 6.0).(4)All of the data were analyzed by statistical software SPSS 25.0English version.P<0.05 was considered to be statistically significant.Results:(1)A total of 355 eyes of 231 myopic patients(male:101cases)were selected in the first part,with an average age of(26.31±6.40)years.Mild myopia group(AL1)47 eyes of 36 cases(male:17 cases)with an average age of(23.21±6.32)years,and the moderate myopia group(AL2)94 eyes of 57 cases(male:22 cases).(26.56±5.98)years old;137 eyes of 87 cases(male:22 cases)in high myopia group(AL3),(27.80±6.81)years old,77eyes of 51 cases(male:40 cases)in ultra-high myopia group(AL4),(25.23±5.38)years old.The second part included 78 cases(113 eyes)with an average age of(27.68±8.78)years.Among them,20 cases(male:16 cases)in POAG+HM group,30 eyes,(34.4±10.65)years,and 31 cases(male:9 cases)in HM group,45 eyes,age(27.29±5.66)years old;mild myopia The mild myopia group(control group)included 27 cases(male:14 cases)with 38 eyes,with an average age of(22.84±6.73)years.(2)The correlation coefficient between optic disc tilt rate and horizontal tilt angle was 0.503(P<0.001);and the correlation coefficient between optic disc tilt rate and vertical tilt angle was 0.368(P<0.001).The optic disc area of the AL3 group was the smallest,followed by the AL2,AL4,and AL1 groups,which were(1.83±0.43)mm~2,(2.04±0.4)mm~2,(2.12±0.66)mm~2,and(2.28±0.44)mm~2,respectively.(3)The areas ofβ-PPCA in groups AL1～AL4 were(0.55±0.14)mm~2,(0.98±0.50)mm~2,(1.30±0.75)mm~2,and(1.68±1.12)mm~2,respectively.The number and percentage ofβ-PPCA eyes were 5 eyes(10.6%)in AL1group,54 eyes(57.4%)in AL2 group,120 eyes(87.6%)in AL3 group,and 74 eyes(96.1%)in AL4 group.The percentage ofβ-PPCA in each group increased gradually,and the ratio ofβ-PPCA area to optic disc area gradually increased in each group.(4)The optic disc tilt rate was 1.32±0.14 in AL3 group,followed by1.25±0.13 in AL2 group,and 1.17±0.08 in AL1 group.The number and percentage of tilted optic disc eyes in AL1～AL4 groups were 3 eyes(6.4%),24 eyes(25.5%),71 eyes(51.8%),29 eyes(37.7%),AL1～AL3groups,the proportion of tilted optic disc increased gradually.(5)Compared with HM group and mild myopia group,POAG+HM group had the largest optic disc tilt rate,which was 1.35±0.32.The number and percentage of tilted optic disc eyes were 13 eyes(43.3%)in POAG+HM group,15 eyes(33.3%)in HM group,and 2 eyes(5.3%)in mild myopia group.(6)The area ofβ-PPCA in POAG+HM group was(2.19±1.53)mm~2,HM group(1.21±1.09)mm~2,and mild myopia group(0.02±0.11)mm~2.The number and percentage ofβ-PPCA eyes were 29 eyes(96.7%)in POAG+HM group,37 eyes(82.2%)in HM group,and 2 eyes(5.3%)in mild myopia group.Conclusion:(1)The increase inβ-PPCA area may be the main feature of the progression of high myopia.(2)High myopia patients with optic disc tilt should be alert to the possibility of POAG.(3)The optic disc tilt rate based on fundus photography and the optic disc tilt angle based on OCT cannot be replaced with each other,and should be combined with each other to better evaluate the morphological changes of the optic disc in high myopia.