Automated evaluation of parapapillary choroidal microvasculature in crowded optic discs:a controlled,optical coherence tomography angiography study

AIM:To compare superficial and deep vascular properties of optic discs between crowded discs and controls using optical coherence tomography angiography(OCT-A).METHODS:Thirty patients with crowded discs,and 47 control subjects were enrolled in the study.One eye of each individual was included and OCT-A scans of optic discs were obtained in a 4.5×4.5 mm^(2) rectangular area.Radial peripapillary capillary(RPC)density,peripapillary retinal nerve fiber layer(pRNFL)thickness,cup volume,rim area,disc area,cup-to-disc(c/d)area ratio,and vertical c/d ratio were obtained automatically using device software.Automated parapapillary choroidal microvasculature(PPCMv)density was calculated using MATLAB software.When the vertical c/d ratio of the optic disc was absent or small cup,it was considered as a crowded disc.RESULTS:The mean signal strength index of OCT-A images was similar between the crowded discs and control eyes(P=0.740).There was no difference in pRNFL between the two groups(P=0.102).There were no differences in RPC density in whole image(P=0.826)and peripapillary region(P=0.923),but inside disc RPC density was higher in crowded optic discs(P=0.003).The PPCMv density in the inner-hemisuperior region was also lower in crowded discs(P=0.026).The pRNFL thickness was positively correlated with peripapillary RPC density(r=0.498,P<0.001).The inside disc RPC density was negatively correlated with c/d area ratio(r=-0.341,P=0.002).CONCLUSION:The higher inside disc RPC density and lower inner-hemisuperior PPCMv density are found in eyes with crowded optic discs.

Measurements of the parapapillary atrophy area and other fundus morphological features in high myopia with or without posterior staphyloma and myopic traction maculopathy

AIM:To investigate the affecting factors of parapapillary gamma and delta zones and other fundus morphological features in high myopia.METHODS:Seventy high myopia patients were included in this retrospective observational study and 47 patients were female.Patients were divided into three groups:no posterior staphyloma(no PS),PS with myopic traction maculopathy(PS with MTM),and PS without MTM using 3-dimensional magnetic resonance imaging and optical coherence tomography.MTM patients were fur ther classified into three types[epiretinal membrane,macular hole,and macular retinoschisis(MRS)].Diameters of the gamma and delta zones were measured among other morphometric variables using fundus photographs.RESULTS:Of the 70 individuals(127 eyes),the mean age was 57.46±13.56y.In univariate analysis,morphological features changed most dramatically in PS with MTM patients,who had the largest gamma zone diameters,the largest disk-fovea distance(DFD)and disk-fovea angle,and the smallest angle kappa and vertical distance of temporal arterial arcade.However,their horizontal delta zone diameter was smaller than in the patients with PS yet without MTM.In multivariate analysis,with axial length(AL)and age adjusted,the horizontal diameter in the delta zone of the PS without MTM group was still significantly larger than in the PS with MTM group(P=0.024).Comparing the three subtypes of MTM patients,the diameters of the gamma zone and DFD in MRS group were the largest.CONCLUSION:The characteristics of the gamma and delta zones change inconsistently in different stages of high myopia.These changes may be associated with anatomical changes caused by local traction.Factors such as PS,AL and age play an important role.These findings may provide a hint about the pathogenesis of traction in high myopia.

Commentary review on peripapillary morphological characteristics in high myopia eyes with glaucoma:diagnostic challenges and strategies

The incidences of open angle glaucoma(OAG)and high myopia are increasing concomitantly.Considering the aging population and concurrent rapid increase in the number of individuals with myopia,the risk of visual defects caused by highly myopic OAG is likely to increase dramatically over the next few decades.However,precise screening and diagnosis of OAG is challenging because of the tilt and rotation of the optic disc,as well as extensiveβ-zone parapapillary atrophy in highly myopic eyes.Recent advances in optical coherence tomography(OCT)and OCT angiography(OCTA)technologies imply that both modalities are promising tools for the detection of highly myopic OAG.Notably,the diagnosis of OAG remains to be determined with the longitudinal changes of functional damages(e.g.visual field defect,visual electrophysiological changes).We herein describe some aspects of microvascular and microstructural pathology in patients with highly myopic OAG and proposes a framework for the development of novel diagnostic and therapeutic strategies.

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.