| Objective:Non-arteritic anterior ischemic optic neuropathy(NAION)is a common clinical disease,which can lead to acute vision loss.It is suggested that NAION is caused by the abrupt poor perfusion in the optic nerve head from the branches of the central retinal artery and the posterior ciliary artery not due to the arteritis,it is characterized by sudden,painless loss of visual acuity and visual field,associated with the segmental optic disc swelling,and the onset age older than 45 years.The visual field defect of NAION is irreversible and will affect the patient's visual function and life seriously.Therefore,NAION needs to be diagnosed and treated,especially to be prevented.It is necessary to pay attention to the anatomical abnormalities,as well as the change of the micro-perfusion around and in the optic papillae,which may be important for screening the high-risk population of NAION.Optical coherence tomography angiography(OCTA)can observe the vascular distribution and the blood flow at the different levels and different regions of the retina and choroid,especially optic disc and macula,which provides more favorable evidences for the diagnosis and treatment of NAION.In this paper,we collected the vessel density(VD)in the retinal peripapillary capillaries(RPC),the whole optic disc(Whole Image)and the inner part of the optic disc(Inside Disc),and the peripapillary retinal nerve fiber layer(pRNFL)thickness of NAION and the normal in OCTA,compared the differences between VD and pRNFL in different regions in the affected and the contralateral healthy eyes of NAION and the normal eyes,and analyze the correlationship between VD of OCTA and mean sensitivity(MS)of the visual field in the ischemic region.The aim was to find the high-risk factors for the abnormal micro-perfusion in and around the optic papilla in NAION,which can provide a new basis for early diagnosis,treatment and prevention of NAION.Methods:1.A total of 80 volunteers(160 eyes)with the refractive error within±3.00D and no any previous medical histories of fundus,optic neuropathy,hypertension,diabetes,nephropathy and others were collected.35 patients with NAION were collected,15 patients with the course of NAION in 2 weeks and 20 patients more than 6 months.All subjects underwent medical history collection,binocular color fundus photography,Goldmann intraocular pressure and the best corrected visual acuity tests.All performed OCTA examination without mydriasis to obtain high-definition scanning images in the optic disc of 4.5x4.5mm size.VD of RPC?Whole Image,Inside Disc,pRNFL and the blood flow pictures of optic disc were obtained by the built-in analysis software.All subjects were performed the visual field tests by 24-2 standard pattern on the Humphrey Field Analyzer,whose false negative rate and false positive rate were both<15%,and the fixation loss rate was<20%.2.A45 represents people above 45 years old,B45 below 45 years old,M men,F women,and N normal.In the normal group,it is divided into AM45,AF45,BM45,BF45,AN45,BN45,NM and NF groups.The differences of VD in RPC,Whole Image and inside disc,and pRNFL between the normal ones with different gender,age and different eyes were observed.The correlationship between VD and pNRFL in the corresponding regions were observed.3.AI represents the affected eye,and AN contralateral healthy eye in the acute ischemia of NAION.BI represents the affected eye,and BN contralateral healthy eye in the chronic atrophy of NAION.C represents the normal eyes for control.The differences of those above parameters between AI and AN,BI and BN,AN and C,BN and C,AI and BI,and AN and BN,even the ischemic and non-ischemic region of the affected eyes were observed.4.The correlationship between VD(RPC),pRNFL,MS,and MD in the corresponding ischemic region of the optic disc in the acute and chronic phase of NAION.Results:A total of 140 subjects were enrolled in the study.58 eyes were excluded due to the refractive error,poor patient coordination,and other factors leading to low-quality.Finally,we selected 222 eyes from 111 subjects to carry out the data analysis,including 160 healthy eyes,35 affected eyes and 35 contralateral healthy eyes of NAION.1.Symmetry analysis on VD and pRNFL in the normal adult eyes.In the normal adults,it revealed that VD(RPC-OD)of BN45(52.222±2.36%)was less than the one of AN45(53.51 ± 1.88%)(P<0.05),but the difference was only-1.29±2.20%,VD(Inside Disc)of BN45(48.50±5.09%)was more than the one of AN45(46.84±4.49%),and VD(RPC-OU)of BN45(48.50±5.09%)was 1.03±2.43%less than the one of AN45(53.38±2.33%)(P<0.05).VD(RPC-OS)of NM and NF only differed by 1.09±2.62%(P>0.05),which had no practical significance in the clinic.There was no difference of VD in the different regions of the rest of groups(P>0.05).There was a positive correlation between VD and pRNFL in the superior half(r=0.408,P<0.001),and as the same result in the inferior half(r=0.307,P<0.001).2.Analysis on the characteristics of NAION optic disc in OCT A.1)Compared the affected and contralateral healthy eyes in the acute ischemic NAION,VD(Whole Image)of AI(29.5±4.62%)was less than that of AN(50.14±2.37%)(P<0.05),VD(Inside Disc)of AI(37.25±4.12%)was less than that of AN(44.45±4.50%)(P<0.05),and VD(RPC)AI(40.31±4.78%)was also less than that of AN(54.07±2.64%)(P<0.05).pRNFL of AI(195.50±42.14?m)was less than that of AN(132.90±7.27?m)(P<0.05).2)Compared the affected and contralateral healthy eyes in the chronic areophic NAION,VD(Whole Image)of BI(36.48±5.32%)was less than that of BN(49.17±2.71%)(P<0.05),VD(Inside Disc)of BI(41.98±4.96%)was less than that of BN(46.28±3.59%)(P<0.05),and VD(RPC)of BI(35.62±6.54%)was also less than that of BN(52.15±2.95%)(P<0.05),while pRNFL of BI(92.58±16.26?m)was thicker than that of BN(128.60±18.84?m)(P<0.05).3)Compared the contralateral healthy eyes in NAION and the normal eyes,VD(Inside Disc)of AN(44.45±4.15%)was less than that of C(46.85±4.49%)(P<0.05),while pRNFL of the AN(132.90±7.27?m)was thicker than C(128.80±5.69?m)(P<0.05).4)Study on the relationship between function and anatomy in the ischemic region of NAION optic disc.VD(RPC)in the ischemic region of NAION(29.97±6.54%)was less than that in the non-ischemic region(43.20±6.28%)(P<0.05).According to the modified Garway-Heath partition method,there was no statistically significant about the correlation between VD,pRNFL,MS and MD in the ischemic region of AI(P>0.05),and a statistically significant negative correlation between VD and MS in the ischemic region of BI(r=-0.538,P=0.038).Conclusion:1.The micro-perfusion of blood flow and retinal nerve fiber layes in both eyes of the normal adults were symmetric with a little difference,which was none of business about age and gender.2.The vessel densities in the ischemic RPC,inside the disc and within the whole disc reduced in the acute affected eyes of NAION,which was different from the increasing nerve fiber layer thickness.If these changes corresponds to the local visual field defects,it may be an important basis for diagnosis and differential diagnosis.3.The vessel densities in the ischemic RPC,inside the disc and within the whole disc,and pRNFL reduced in the atrophic affected eyes of NAION,which was corresponding to the local visual field defect.4.The vessel density inside the optic disc of the contralateral healthy eye of NAION was less than the normal one,while pRNFL was thicker.If we can find the threshold vessel density of the risk for NAION in the enlarged study,it may become an important basis for prevention of NAION.5.OCT A is a new,rapidly,non-invasive,reproducible and contrast-free angiography technology,which can obtain the vascular distribution and the blood flow at different levels of the optic disc.It is an important guide for the study on the pathogenesis,development,treatment and follow-up of NAION. |
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