Repeatability,interocular correlation and agreement of optic nerve head vessel density in healthy eyes:a sweptsource optical coherence tomographic angiography study

AIM:To assess the repeatability,interocular correlation,and agreement of quantitative swept-source optical coherence tomography angiography(OCTA)optic nerve head(ONH)parameters in healthy subjects.METHODS:Thir ty-three healthy subjects were enrolled.The ONH of both eyes were imaged four times by a swept-source-OCTA using a 3 mm×3 mm scanning protocol.Images of the radial peripapillary capillary were analyzed by a customized Matlab program,and the vessel density,fractal dimension,and vessel diameter index were measured.The repeatability of the four scans was determined by the intraclass correlation coefficient(ICC).The most well-centered optic disc from the four repeated scans was then selected for the interocular correlation and agreement analysis using the Pearson correlation coefficient,ICC and Bland-Altman plots.RESULTS:All swept-source-OCTA ONH parameters exhibited certain repeatability,with ICC>0.760 and coefficient of variation(CoV)≤7.301%.The obvious interocular correlation was observed for papillary vessel density(ICC=0.857),vessel diameter index(ICC=0.857)and fractal dimension(ICC=0.906),while circumpapillary vessel density exhibited moderate interocular correlation(ICC=0.687).Bland-Altman plots revealed an agreement range of-5.26%to 6.21%for circumpapillary vessel density.CONCLUSION:OCTA ONH parameters demonstrate good repeatability in healthy subjects.The interocular correlations of papillary vessel density,fractal dimension and vessel diameter index are high,but the correlation for circumpapillary vessel density is moderate.

Changes of optic nerve head microcirculation in high myopia

AIM:To analyze the correlation of age,spherical equivalent(SE),and axial length(AL)with the microcirculation of optic nerve head(ONH)in high myopia(HM).METHODS:In this cross-sectional clinical study,164 right eyes were included.Optical coherence tomography angiography(OCTA)was used to detect ONH vessel density.Eyes were classified based on age,SE,and AL.Groups of Age1,Age2,and Age3 were denoted for age classification(Age1<20y,20y≤Age2<30y,Age3≥30y);Groups SE1,SE2,and SE3 for the SE classification(-9≤SE1<-6 D,-12≤SE2<-9 D,SE3<-12 D);Groups AL1,AL2,AL3,and AL4 for the AL classification(AL1<26 mm,26≤AL2<27 mm,27≤AL3<28 mm,AL4≥28 mm).RESULTS:No significant difference was observed in vessel density among the Age1,Age2,and Age3 groups(all P>0.05)and the SE1,SE2,and SE3 groups(all P>0.05).No significant difference was observed in the intrapapillary vascular density(IVD)among AL1,AL2,AL3,and AL4 groups(P>0.05).However,a significant decrease was found in the peripapillary vascular density(PVD)in the AL1,AL2,AL3,and AL4 groups(F=3.605,P=0.015),especially in the inferotemporal(IT;F=6.25,P<0.001),temporoinferior(TI;F=2.865,P=0.038),and temporosuperior(TS;F=6.812,P<0.001)sectors.The IVD was correlated with age(r=-0.190,P<0.05)but not with SE or AL(P>0.05).The PVD was correlated with AL(r=-0.236,P<0.01)but not with age or SE(P>0.05).CONCLUSION:With the increase of AL,the IVD remains stable while the PVD decreases,especially in the three directions of temporal(IT,TI,and TS).The main cause of microcirculation reduction may be related to AL elongation rather than an increase in age or SE.

Evaluation of optic nerve head vessels density changes after phacoemulsification cataract surgery using optical coherence tomography angiography

·AIM:To evaluate optic nerve head(ONH)vessel density(VD)changes after cataract surgery using optical coherence tomography angiography(OCTA).·METHODS:This was a prospective observational study.Thirty-four eyes with mild/moderate cataracts were included.ONH scans were obtained before and 3mo after cataract surgery using OCTA.Radial peripapillary capillary(RPC)density,all VD,large VD and retinal nerve fiber layer thickness(RNFLT)in total disc,inside disc,and different peripapillary sectors were assessed and analyzed.Image quality score(QS),fundus photography grading and bestcorrected visual acuity(BCVA)were also collected,and correlation analyses were performed between VD change and these parameters.·RESULTS:Compared with baseline,both RPC and all VD increased in inside disc area 3mo postoperatively(from 47.5%±5.3%to 50.2%±3.7%,and from 57.87%±4.30%to 60.47%±3.10%,all P<0.001),but no differences were observed in peripapillary area.However,large VD increased from 5.63%±0.77%to 6.47%±0.72%in peripapillary ONH region(P<0.001).RPC decreased in inferior and superior peripapillary ONH parts(P=0.019,<0.001 respectively).There were obvious negative correlations between RPC change and large VD change in inside disc,superior-hemi,and inferior-hemi(r=-0.419,-0.370,and-0.439,P=0.017,0.044,and 0.015,respectively).No correlations were found between VD change and other parameters including QS change,fundus photography grading,postoperative BCVA,and postoperative peripapillary RNFLT.·CONCLUSION:RPC density and all VD in the inside disc ONH region increase 3mo after surgery in patients with mild to moderate cataract.No obvious VD changes are found in peripapillary area postoperatively.

Vessel density in OCT angiography permits differentiation between normal and glaucomatous optic nerve heads

AIM：To evaluate whether optical coherence tomography angiography（OCTA） can detect altered vessel density（VD） at the optic nerve head（ONH） in glaucoma patients.Special attention is paid to the accuracy of the OCTA technique for distinguishing healthy from glaucomatous eyes.METHODS：A total of 171 eyes were examined by the OCTA system Angio Vue^TM（Optovue）：97 eyes diagnosed with glaucoma and 74 healthy control eyes.The papillary and peripapillary VD was measured.Furthermore,the VD was correlated with different structural and functional measurements.In order to test the accuracy of differentiation between eyes with and without glaucoma,we calculated the receiver operating characteristic curve（ROC） and the area under the curve（AUC）.RESULTS：The papillary and peripapillary VD in glaucomatous eyes was significantly lower than in healthy eyes（P〈0.05）.The VD of the nasal peripapillary sector was significantly lower than in the other sectors.The further the disease had progressed [measured by determining the thickness of the ganglion cell complex（GCC） and the retinal nerve fiber layer（RNFL）] the greater the VD reduction.The AUC discriminated well between glaucomatous and normal eyes（consensus classifier 94.2%）.CONCLUSION：OCTA allows non-invasive quantification of the peripapillary and papillary VD,which is significantly reduced in glaucomatous eyes and accurately distinguishes between healthy and diseased eyes.OCTA expands the spectrum of procedures for detecting and monitoring glaucoma.

Effect of femtosecond laser-assisted lens surgery on the optic nerve head and the macula

AIM: To evaluate the effect of femtosecond laser-assisted lens surgery(FLALS;cataract surgery or refractive lens exchange) on the structure of the optic nerve head and the macula.METHODS: This prospective longitudinal study included healthy eyes undergoing FLALS. Eyes with glaucoma or any other ocular disease that could alter optical coherence tomography results were excluded. Retinal nerve fiber layer(RNFL), Bruch’s membrane opening-minimum rim width(BMO-MRW) and macular thickness(MT) were measured preoperatively, 1 and 6 mo after surgery using spectral-domain optical coherence tomography(SD-OCT). Changes between preoperative and postoperative values were evaluated.RESULTS: A total of 87 eyes of 46 patients were included in this study. Preoperative RNFL, BMO-MRW and MT in microns(μm) were 100.77±10.39, 330.31±49.99 and 276.30±33.39, respectively. Postoperative RNFL, BMO-MRW and MT were 104.74±11.55, 348.32±54.05 and 279.83±22.65 1 mo after surgery and 102.93±11.17, 343.11±53.4 and 278.90±22.19 6 mo after surgery, respectively;which equals an increase of 3.93%, 5.45% and 1.27%,respectively, 1 mo after surgery, and 2.14%, 3.87% and 0.94% 6 mo after surgery. The differences between the preoperative and the postoperative RNFL and BMO-MRW values were statistically significant(P<0.001). Regarding MT values, there were not statistically significant differences(P=0.26).CONCLUSION: Our study suggests that FLALS does not have a negative impact on the structural status of the optic nerve head in healthy eyes, assessed by SD-OCT. There is a slight increase in the values of RNFL, BMO-MRW and MT 1 mo and 6 mo after surgery.

Spectral domain optical coherence tomography crosssectional image of optic nerve head during intraocular pressure elevation

AIM: To analyze changes of the optic nerve head(ONH) and peripapillary region during intraocular pressure(IOP) elevation in patients using spectral domain optical coherence tomography(SD-OCT).METHODS: Both an optic disc 200×200 cube scan and a high-definition 5-line raster scan were obtained from open angle glaucoma patients presented with monocular elevation of IOP(≥30 mm Hg) using SD-OCT. Additional baseline characteristics included age, gender, diagnosis,best-corrected visual acuity, refractive error, findings of slit lamp biomicroscopy, findings of dilated stereoscopic examination of the ONH and fundus, IOP, pachymetry findings, and the results of visual field.RESULTS: The 24 patients were selected and divided into two groups: group 1 patients had no history of IOP elevation or glaucoma(n =14), and group 2 patients did have history of IOP elevation or glaucoma(n =10). In each patient, the study eye with elevated IOP was classified into group H(high), and the fellow eye was classified into group L(low). The mean deviation(MD)differed significantly between groups H and L when all eyes were considered(P =0.047) and in group 2(P =0.042), not in group 1(P =0.893). Retinal nerve fiber layer(RNFL) average thickness(P =0.050), rim area(P =0.015),vertical cup/disc ratio(P =0.011), cup volume(P =0.028),inferior quadrant RNFL thickness(P =0.017), and clockhour(1, 5, and 6) RNFL thicknesses(P =0.050, 0.012, and0.018, respectively), cup depth(P =0.008), central prelaminar layer thickness(P =0.023), mid-inferior prelaminar layer thickness(P =0.023), and nasal retinal slope(P =0.034)were significantly different between the eyes with groups H and L.CONCLUSION:RNFLaveragethickness,rim area,vertical cup/disc ratio, cup volume, inferior quadrant RNFL thickness, and clock-hour(1, 5, and 6) RNFL thicknesses significantly changed during acute IOP elevation.

Intraretinal layer segmentation and parameter measurement in optic nerve head region through energy function of spatial-gradient continuity constraint

For the diagnosis of glaucoma,optical coherence tomography(OCT)is a noninvasive imaging technique for the assessment of retinal layers.To accurately segment intraretinal layers in an optic nerve head(ONH)region,we proposed an automatic method for the segmentation of three intraretinal layers in eye OCT scans centered on ONH.The internal limiting membrane,inner segment and outer segment,Bruch’s membrane surfaces under vascular shadows,and interaction of multiple high-reflectivity regions in the OCT image can be accurately segmented through this method.Then,we constructed a novel spatial-gradient continuity constraint,termed spatial-gradient continuity constraint,for the correction of discontinuity between adjacent image segmentation results.In our experiment,we randomly selected 20 B-scans,each annotated three retinal layers by experts.Signed distance errors of?0.80μm obtained through this method are lower than those obtained through the state-of-art method(?1.43μm).Meanwhile,the segmentation results can be used as bases for the diagnosis of glaucoma.

Influence of corneal power on circumpapillary retinal nerve fiber layer and optic nerve head measurements by spectral-domain optical coherence tomography

AIM：To evaluate the influence of corneal power on circumpapillary retinal nerve fiber layer（cp RNFL）and optic nerve head（ONH）measurements by spectral-domain optical coherence tomography（SD-OCT）.METHODS：Twenty-five eyes of 25 healthy participants（mean age 23.6±3.6y）were imaged by SD-OCT using horizontal raster scans.Disposable soft contact lenses of different powers（from-11 to＋5 diopters including 0diopter）were worn to induce 2-diopter changes in corneal power.Differences in the cp RNFL and ONH measurements per diopter of change in corneal power were analyzed.RESULTS：As corneal power increased by 1 diopter,total and quadrant cp RNFL thicknesses,except for the nasal sector,decreased by-0.19 to-0.32μm（P〈0.01）.Furthermore,the disc,cup,and rim areas decreased by-0.017,-0.007,and-0.015 mm2,respectively（P〈0.001）;the cup and rim volumes decreased by-0.0013 and-0.006 mm3,respectively（P〈0.01）;and the vertical and horizontal disc diameters decreased by-0.006 and-0.007 mm,respectively（P〈0.001）.CONCLUSION：For more precise OCT imaging,the ocular magnification should be corrected by considering both the axial length and corneal power.However,the effect of corneal power changes on cp RNFL thickness and ONH topography are small when compare with those of the axial length.

Correlations between corneal and optic nerve head variables in healthy subjects and patients with primary open angle glaucoma

AIMTo correlate corneal variables (determined using the Pentacam) with optic nerve head (ONH) variables determined using the Heidelberg retina tomograph (HRT) in healthy subjects and patients diagnosed with primary open angle glaucoma (POAG).METHODSMeasurements were made in 75 healthy eyes and 73 eyes with POAG and correlations examined through Pearson correlation coefficients between the two sets of variables in the two subject groups. The corneal variables determined were corneal volume (CVol), central corneal thickness (CCT), overall corneal thickness (OvCT), the mean thickness of a circular zone centered at the corneal apex of 1 mm radius (zone I) and the mean thickness of several concentric rings, also centered at the apex until the limbus, each of 1 mm width (zones II to VI respectively). The ONH variables were determined using the HRT.RESULTSThe following pairs of variables were correlated in the control group: CCT-disc area (DAr) (-0.48; P&#x0003c;0.0001), Zone I-DAr (-0.503; P&#x0003c;0.0001) and Zone II-DAr (-0.443; P&#x0003c;0.0001); and in the POAG group: CCT-cup-to-disc area ratio (CDRa) (-0.402; P&#x0003c;0.0001), Zone I-CDRa (-0.418; P&#x0003c;0.0001), Zone II-CDRa (-0.405; P=0.006), Zone I-cup shape measure (CSM) (-0.415; P=0.002), Zone II-CSM (-0.405; P=0.001), Zone IV-height variation contour (HVC) (0.378; P=0.002); Zone V-HVC (0.388, P&#x0003c;0.0001).CONCLUSIONSIn the healthy subjects, significant negative correlation was detected between central and paracentral corneal thickness and optic disc area. In contrast, the POAG patients showed significant negative correlation between central and paracentral corneal thickness and the cup-disc ratio and CSM, and positive correlation between peripheral corneal thickness and HVC.

Optical coherence tomography angiography of the optic nerve head, current situation and future perspective

The circulation of the optic nerve head is derived from two sources;the prelaminar,laminar and retrolaminar circulation are mainly arise from the posterior ciliary artery circulation,whereas the nerve fiber layer over the optic disc is fed by central retinal artery(1,2).A variety of optic neuropathies with ischemic,glaucomatous,inflammatory and hereditary etiologies may affect the

The in vivo 3D Optic Nerve Head Modeling Based on Human Multimodality Images

Introduction： The human optic nerve head （ONH） is vulnerable to the damage in glaucomatous high intraocular pressure （IOP）. In order to analyze the human ONH head stress and deformation in high IOP, an in vivo three-dimensional （3D） ONH model was reconstructed by optical coherence tomography （OCT） images and magnetic resonance imaging （MRI） images. Materials and Methods： A human eye was scanned by MRI and OCT in serial imaging protocol. The sclera and ONH were segmented from the images, and 3D models were reconstructed by multimodality image registration. Through the morphological segmentation, part of lamina cribrosa （LC） was acquired and reconstructed in combination with the ONH and sclera. Results： The models of ONH and sclera were got, the part of LC was included in the model. In the analysis of FEM, the ONH was compressed and the cup/disk ratio was changed obviously in high glaucomatous IOP. Discussion： This study described a method to build a 3D in vivo ONH model by image processing. It can be used in biomechanieal analysis, and provide the stress state of ONH for the research about the fundus damage of glaucoma.

Comparison of cross sectional optical coherence tomography images of elevated optic nerve heads across acquisition devices and scan protocols

Background:Optic nerve head measurements extracted from optical coherence tomography(OCT)show promise for monitoring clinical conditions with elevated optic nerve heads.The aim of this study is to compare reliability within and between raters and between image acquisition devices of optic nerve measurements derived from OCT scans in eyes with varying degrees of optic nerve elevation.Methods:Wide angle line scans and narrow angle radial scans through optic nerve heads were obtained using three spectral domain(SD)OCT devices on 5 subjects(6 swollen optic nerves,4 normal optic nerves).Three raters independently semi-manually segmented the internal limiting membrane(ILM)and Bruch’s membrane(BM)on each scan using customized software.One rater segmented each scan twice.Segmentations were qualitatively and quantitatively compared.Inter-rater,intra-rater and inter-device reliability was assessed for the optic nerve cross sectional area calculated from the ILM and BM segmentations using intraclass correlation coefficients and graphical comparison.Results:Line scans from all devices were qualitatively similar.Radial scans for which frame rate could not be adjusted were of lower quality.Intra-rater reliability for segmentation and optic nerve cross sectional area was better than inter-rater reliability,which was better than inter-device reliability,though all ICC exceeded 0.95.Reliability was not impacted by the degree of optic nerve elevation.Conclusions:SD-OCT devices acquired similar quality scans of the optic nerve head,with choice of scan protocol affecting the quality.For image derived markers,variability between devices was greater than that attributable to inter and intra-rater differences.

Structural measurements and vessel density of spectraldomain optic coherence tomography in early,moderate,and severe primary angle-closure glaucoma

AIM:To compare the macular ganglion cell-inner plexiform layer(GCIPL)thickness,retinal nerve fiber layer(RNFL)thickness,optic nerve head(ONH)parameters,and retinal vessel density(VD)measured by spectral-domain optical coherence tomography(SD-OCT)and analyze the correlations between them in the early,moderate,severe primary angle-closure glaucoma(PACG)and normal eyes.METHODS:Totally 70 PACG eyes and 20 normal eyes were recruited for this retrospective analysis.PACG eyes were further separated into early,moderate,or severe PACG eyes using the Enhanced Glaucoma Staging System(GSS2).The GCIPL thickness,RNFL thickness,ONH parameters,and retinal VD were measured by SD-OCT,differences among the groups and correlations within the same group were calculated.RESULTS:The inferior and superotemporal sectors of the GCIPL thickness,rim area of ONH,average and inferior sector of the retinal VD were significantly reduced(all P<0.05)in the early PACG eyes compared to the normal and the optic disc area,cup to disc ratio(C/D),and cup volume were significantly higher(all P<0.05);but the RNFL was not significant changes in early and moderate PACG.In severe group,the GCIPL and RNFL thickness were obvious thinning with retinal VD were decreasing as well as C/D and cup volume increasing than other three groups(all P<0.01).In the early PACG subgroup,there were significant positive correlations between retinal VD and GCIPL thickness(except superonasal and inferonasal sectors,r=0.573 to 0.641,all P<0.05),superior sectors of RNFL thickness(r=0.055,P=0.049).More obvious significant positive correlations were existed in moderate PACG eyes between retinal VD and superior sectors of RNFL thickness(r=0.650,P=0.022),and temporal sectors of RNFL thickness(r=0.740,P=0.006).In the severe PACG eyes,neither GCIPL nor RNFL thickness was associated with retinal VD.CONCLUSION:The ONH damage and retinal VD loss appears earlier than RNFL thickness loss in PACG eyes.As the PACG disease progressed from the early to the moderate stage,the correlations between the retinal VD and RNFL thickness increases.

Parameters of ocular fundus on spectral-domain optical coherence tomography for glaucoma diagnosis

In this review, we summarize the progression of several parameters assessed by spectral-domain optical coherence tomography （SD-OCT） in recent years for the detection of glaucoma. Monitoring the progression of defects in the retinal nerve fiber layer （RNFL） thickness is essential. Imaging and analysis of retinal ganglion cells （RGCs） and inner plexiform layer （IPL）, respectively, have been of great importance. Optic nerve head （ONH） topography obtained from 3D SD-OCT images is another crucial step. Other important assessments involve locating the Bruch＇s membrane opening （BMO）, estimating the optic disc size and rim area, and measuring the lamina cribrosa displacement. Still other parameters found in the past three years for glaucoma diagnosis comprise central retinal artery resistive index, optic disc perfusion in optical coherence tomography angiography （OCTA） study, peripapillary choroidal thickness, and choroidal area in SD-OCT. Recently, several more ocular fundus parameters have been found, and compared with the earlier parameters to judge the accuracy of diagnosis. While a few of these parameters have been widely used in clinical practice, a fair number are still in the experimental stage.

Analysis of retinal vasculature changes in indirect traumatic optic neuropathy using optic coherence tomography angiography

AIM:To assess the retinal vasculature alterations in indirect traumatic optic neuropathy(ITON)patients following craniofacial trauma by optic coherence tomography angiography(OCTA).METHODS:Patients diagnosed of monocular ITON were recruited from August 2016 to May 2020.OCTA was performed using the Angio Vue OCT-A system for two cube scans centered at the optic nerve head and fovea.OCTA data included thicknesses of peripapillary retinal nerve fiber layer(RNFL)and macular ganglion cell complex(GCC),as well as proportion of capillary perfusion and data were analyzed for correlation with post-injury timepoints:within 7,8-30,31-90,and 91-365d.RESULTS:A total of 73 ITON patients were studied.Significant thinning of RNFL and GCC layers and attenuation of microvascular perfusion were observed in ITON eyes as compared to contralateral unaffected eyes(for most of the analyzed sectors and quadrants,P<0.05).Without respect to surgical intervention and vision recovery,the decrease in retinal layer thicknesses and microvascular perfusion was time-dependent,and most significant within three months(P<0.001).CONCLUSION:ITON presents with time-dependent thinning of retinal layers and attenuation of microvasculature,indicating possible degeneration of retinal ganglion cells due to reduced retinal blood supply.

Hub Genes of Astrocyte Involved in Glaucoma with Ocular Hypertension by Integrated Bioinformatics Analysis

This study was conducted to elucidate the potential key candidate genes and pathways in role of astrocyte involved in glaucoma with ocular hypertension.Methods Expression profiles GSE2378 and GSE758 including 27 reactive optic nerve head astrocytes(ONHAs)by hypertensions and 26 normal controls,were integrated and deeply analyzed.Differentially expressed genes(DEGs)were sorted and candidate genes and pathways enrichment were analyzed.DEGs-associated protein-protein interaction network(PPI)was performed.Results A total of 119 consistently expressed genes were identified from 281 commonly changed DEGs,including 68 up-regulated genes and 51 down-regulated genes.PPI network complex filtered 75 DEGs(43 up-regulated and 32 down-regulated genes)of the 119 consistently altered DEGs and developed 117 edges,and 10 hub genes were identified.The most significant 3 modules were filtered from PPI,pathway enrichment analysis showed that module 1 was associated with extracellular exosome.Module 2 was mainly associated with antibody-dependent cellular cytotoxicity(ADCC)and module 3 was mainly associated with Hippo signaling pathway.Conclusion Taken above,using integrated bioinformatical analysis,we have identified DEGs candidate genes and pathways in role of astrocyte involved in glaucoma with ocular hypertension,which could improve our understanding of the cause and underlying molecular events,and these candidate genes and pathways could be therapeutic targets for glaucoma.

Optical coherence tomography angiography at the acute phase of optic disc edema

Background:The differential diagnosis of optic disc edema at the acute phase can be challenging.OCT angiography(OCTA)is a new technology allowing the visualization of the peripapillary vascular network and optic disc capillaries.The peripapillary network alterations of glaucoma and chronic non-arteritic anterior ischemic optic neuropathy(NAION)were reported.However,no OCTA studies on acute optic disc edema from various causes.The aim of this project was to use OCTA to demonstrate the vascular changes the optic nerve head of various types of optic disc edema at the acute phase.Methods:In this retrospective study,patients with non-arteritic anterior ischemic optic neuropathy(NAION),papillitis or papilledema were recruited.Each patient was imaged using the AngioPlex^(TM)CIRRUS^(TM)HD-OCT device(model 5000,Carl Zeiss Meditec,Inc.,Dublin,USA)with a scanning area of 6×6 mm^(2) centered on the optic disc.A morphological analysis of the peripapillary network was performed.For some patients with unilateral optic disc edema,a quantitative analysis was performed using a swept-source OCT-A system(PLEX®Elite 9000,Carl Zeiss Meditec,Inc.,Dublin,USA).Vessel perfusion density and flux index of the peripapillary area were calculated.Results:Eight eyes with NAION(4 patients),12 eyes with papillitis(6 patients)and 25 eyes with papilledema(13 patients)were imaged.The apparent disappearance or moderate pattern alteration of the peripapillary capillary vessels were observed in patients with NAION or papillitis,respectively.For papilledema,the capillaries at the surface of the optic disc were dilated and tortuous,but no peripapillary network pattern changes were observed.The quantitative analysis did not show any difference of peripapillary network between NAION and healthy eyes.For papillitis,the flux index was higher in inflammatory eyes compared to the healthy eyes in average(p=0.03).Conclusion:At the acute phase,the morphological analysis of OCT-A appeared to be more useful than the quantification analysis,facilitating the differentiation between the three kinds of ONH edema:ischemic,inflammatory and papilledema.

Dual-beam delay-encoded all fiber Doppler optical coherence tomography for in vivo measurement of retinal blood flow

In this paper,we propose and demonstrate a dual-beam delay-encoded Doppler spectral domain optical coherence tomography(OCT) system for in vivo measurement of absolute retinal blood velocity and flow with arbitrary orientation.The incident beam is split by a beam displacer into two probe beams of the single-spectrometer spectral domain OCT system with orthogonal polarization states and an optical path length delay.We validate our approach with a phantom and in vivo experiments of human retinal blood flow,respectively.

Advances in myopia research anatomical findings in highly myopic eyes

Background:The goal of this review is to summarize structural and anatomical changes associated with high myopia.Main text:Axial elongation in myopic eyes is associated with retinal thinning and a reduced density of retinal pigment epithelium(RPE)cells in the equatorial region.Thickness of the retina and choriocapillaris and RPE cell density in the macula are independent of axial length.Choroidal and scleral thickness decrease with longer axial length in the posterior hemisphere of the eye,most marked at the posterior pole.In any eye region,thickness of Bruch's membrane(BM)is independent of axial length.BM opening,as the inner layer of the optic nerve head layers,is shifted in temporal direction in moderately elongated eyes(axial length<26.5 mm).It leads to an overhanging of BM into the intrapapillary compartment at the nasal optic disc side,and to an absence of BM at the temporal disc border.The lack of BM at the temporal disc side is the histological equivalent of parapapillary gamma zone.Gamma zone is defined as the parapapillary region without BM.In highly myopic eyes(axial length>26.5 mm),BM opening enlarges with longer axial length.It leads to a circular gamma zone.In a parallel manner,the peripapillary scleral flange and the lamina cribrosa get longer and thinner with longer axial length in highly myopic eyes.The elongated peripapillary scleral flange forms the equivalent of parapapillary delta zone,and the elongated lamina cribrosa is the equivalent of the myopic secondary macrodisc.The prevalence of BM defects in the macular region increases with longer axial length in highly myopic eyes.Scleral staphylomas are characterized by marked scleral thinning and spatially correlated BM defects,while thickness and density of the choriocapillaris,RPE and BM do not differ markedly between staphylomatous versus non-staphylomatous eyes in the respective regions.Conclusions:High axial myopia is associated with a thinning of the sclera and choroid posteriorly and thinning of the retina and reduction of RPE density in the equatorial region,while BM thickness is independent of axial length.The histological changes may point towards BM having a role in the process of axial elongation.

Advances in myopia research anatomical findings in highly myopic eyes

Background:The goal of this review is to summarize structural and anatomical changes associated with high myopia.Main text:Axial elongation in myopic eyes is associated with retinal thinning and a reduced density of retinal pigment epithelium(RPE)cells in the equatorial region.Thickness of the retina and choriocapillaris and RPE cell density in the macula are independent of axial length.Choroidal and scleral thickness decrease with longer axial length in the posterior hemisphere of the eye,most marked at the posterior pole.In any eye region,thickness of Bruch’s membrane(BM)is independent of axial length.BM opening,as the inner layer of the optic nerve head layers,is shifted in temporal direction in moderately elongated eyes(axial length<26.5 mm).It leads to an overhanging of BM into the intrapapillary compartment at the nasal optic disc side,and to an absence of BM at the temporal disc border.The lack of BM at the temporal disc side is the histological equivalent of parapapillary gamma zone.Gamma zone is defined as the parapapillary region without BM.In highly myopic eyes(axial length>26.5 mm),BM opening enlarges with longer axial length.It leads to a circular gamma zone.In a parallel manner,the peripapillary scleral flange and the lamina cribrosa get longer and thinner with longer axial length in highly myopic eyes.The elongated peripapillary scleral flange forms the equivalent of parapapillary delta zone,and the elongated lamina cribrosa is the equivalent of the myopic secondary macrodisc.The prevalence of BM defects in the macular region increases with longer axial length in highly myopic eyes.Scleral staphylomas are characterized by marked scleral thinning and spatially correlated BM defects,while thickness and density of the choriocapillaris,RPE and BM do not differ markedly between staphylomatous versus non-staphylomatous eyes in the respective regions.Conclusions:High axial myopia is associated with a thinning of the sclera and choroid posteriorly and thinning of the retina and RPE density in the equatorial region,while BM thickness is independent of axial length.The histological changes may point towards BM having a role in the process of axial elongation.