Analysis of retinal arteriolar and venular parameters in primary open angle glaucoma

AIM: To measure the retinal vessels of primary open angle glaucoma(POAG) patients on spectral domain optical coherence tomography(SD-OCT) with a full-width at half-maximum(FWHM) algorithm to better explore their structural changes in the pathogenesis of POAG.METHODS: In this retrospective case-control study, the right eyes of 32 patients with POAG and 30 healthy individuals were routinely selected.Images of the supratemporal and infratemporal retinal vessels in the B zones were obtained by SD-OCT, and the edges of the vessels were identified by the FWHM method.The internal and external diameters, wall thickness(WT), wall cross-sectional area(WCSA) and wall-to-lumen ratio(WLR) of the blood vessels were studied.RESULTS: Compared with the healthy control group, the POAG group showed a significantly reduced retinal arteriolar outer diameter(RAOD), retinal arteriolar lumen diameter(RALD) and WSCA in the supratemporal(124.22±12.42 vs 138.32±10.73 μm, 96.09±11.09 vs 108.53±9.89 μm,and 4762.02 ± 913.51 vs 5785.75 ± 114 8.28 μm^(2), respectively, all P<0.05) and infratemporal regions(125.01±15.55 vs 141.57±10.77 μm, 96.27±13.29 vs 110.83 ± 10.99 μm, and 4925.56 ± 1302.88 vs 6087.78±1061.55 μm^(2), all P<0.05).The arteriolar WT and WLR were not significantly different between the POAG and control groups, nor were the retinal venular outer diameter(RVOD), retinal venular lumen diameter(RVLD) or venular WT in the supratemporal or infratemporal region.There was a positive correlation between the arteriolar parameters and visual function.CONCLUSION: In POAG, narrowing of the supratemporal and infratemporal arterioles and a significant reduction in the WSCA is observed, while the arteriolar WT and WLR do not change.Among the venular parameters, the external diameter, internal diameter, WT, WLR, and WSCA of the venules are not affected.

Quantification of radiation damage in natural and synthetic zircon by Raman spectroscopy:application to low-temperature thermochronology

Due to its ubiquitous occurrence in igneous,metamorphic,and sedimentary rocks and its wide application in geochronology and geochemistry,zircon has become the most widely used accessory mineral in the geological community.Nevertheless,the decay of U and Th causes radiation damage to the zircon structure,resulting in various degrees of metamictization,which can affect the accuracy of U–Pb dates and Hf and O isotope results.If the degree of zircon radiation damage can be quantified,the influence on geochemical analyses can be evaluated,and the results can be corrected more precisely.In this paper,synthetic and natural zircon crystals with different crystallization ages were selected for Raman spectroscopy analysis,cathodoluminescence imaging,and determination of the U and Th concentrations.The results show that Raman FWHM(full width at half bandmaximum)and Raman shift correlate with alpha dose(Da)ofzirconsfollowingtheseequations,FWHM=44.36(±2.32)×[1-exp(-2.74×Da)]-+1.7(±0.19),Raman Shift=-6.53×Da+1007.69.Analysis of synthetic zircon crystals shows that doped REEs(rare earth elements and P)can also lead to an increase in the FWHM.However,this effect can be ignored for natural zircon samples with REE contents at a normal level of hundreds to a few thousand ppm.The FWHM and Raman shift can be used as proxies to measure the degree of zircon radiation damage.Using the updated equations to calculate the latest age when zircon began to accumulate radiation damage,a more accurate and more meaningful“radiation damage age”can be obtained.