Chunhui Jiang

Correlation between optic disc perfusion and glaucomatous severity in patients with open-angle glaucoma: an optical coherence tomography angiography study

PurposeTo explore how optic disc perfusion varies in patients with open-angle glaucoma (OAG) and how this correlates with glaucoma severity.MethodsWe performed a prospective and cross-sectional observational study that included 62 eyes from 62 patients with OAG, divided into three groups according to their visual field (VF) results, and 20 eyes from 20 normal control subjects. Optic disc perfusion was studied using optical coherence tomography angiography (angio-OCT), and flow index and vessel density were determined. The VF, mean deviation (MD), pattern standard deviation (PSD), retinal nerve fiber layer (RNFL) thickness, and ganglion cell complex (GCC) thickness were also recorded. The potential associations between disc perfusion and VF defects or structural loss were analyzed.ResultsIn OAG patients, the disc flow index and vessel density were significantly lower than in normal controls (all p<0.001) and were correlated with the severity of glaucoma. In OAG eyes, the flow index and vessel density were significantly correlated with MD, RNFL, and GCC thickness (all p<0.01), but were not in the normal controls. The receiver operating characteristic (ROC) curve analysis also revealed that disc flow index and vessel density had the power to differentiate normal eyes from eyes with OAG (under the ROC curves: 0.82 and 0.80, respectively).ConclusionsAngiograms demonstrated a reduced disc flow index and vessel density in glaucoma, and this reduction was closely related to GCC thickness. This indicated that measurement of disc perfusion by angio-OCT might be important for the monitoring of glaucoma.

Relationship Between Retinal Perfusion and Retinal Thickness in Healthy Subjects: An Optical Coherence Tomography Angiography Study.

Purpose To investigate the relationship between retinal perfusion and retinal thickness in the peripapillary and macular areas of healthy subjects. Methods Using spectral-domain optic coherence tomography and split-spectrum amplitude decorrelation angiography (SSADA) algorithm, retinal perfusion and retinal thicknesses in the macular and peripapillary areas were measured in healthy volunteers, and correlations among these variables were analyzed. Results Overall, 64 subjects (121 eyes) including 28 males and 36 females with a mean ± SD age of 38 ± 13 years participated. Linear mixed-models showed that vessel area density was significantly correlated with the inner retinal thickness (from the inner limiting membrane to the outer border of the inner nucleus layer; P < 0.05), but not with the thickness of the full retina (P > 0.05) in the parafoveal area. The area of the foveal capillary-free zone was negatively correlated with the inner and full foveal thicknesses (all P < 0.001). In the peripapillary area, the vessel area density was positively correlated with the thickness of the retinal nerve fiber layer (P < 0.001). Conclusions In healthy subjects, retinal perfusion in small vessels was closely correlated with the thickness of the inner retinal layers in both the macular and peripapillary areas.

Morphometric measurement of Schlemm’s canal in normal human eye using anterior segment swept source optical coherence tomography

We have used anterior segment swept source optical coherence tomography to measure Schlemms canal (SC) morphometric values in the living human eye. Fifty healthy volunteers with 100 normal eyes were measured in the nasal and temporal side. Comparison with the published SC morphometric values of histologic sections proves the reliability of our results. The statistical results show that there are no significant differences between nasal and temporal SC with respect to their diameter, perimeter, and area in our study (diameter: t=0.122, p=0.903; perimeter: t=-0.003, p=0.998; area: t=-1.169, p=0.244); further, no significant differences in SC morphometric values are found between oculus sinister and oculus dexter (diameter: t=0.943, p=0.35; perimeter: t=1.346, p=0.18; area: t=1.501, p=0.135).

Comparison of Schlemm’s canal’s biological parameters in primary open-angle glaucoma and normal human eyes with swept source optical

Abstract. Thirty-seven normal and primary open angle glaucoma (POAG) subjects were noninvasively imaged by a tailor-made real-time anterior segment swept source optical coherence tomography (SS-OCT) to demonstrate the differences of the Schlemm’s canal (SC) between POAG and normal eyes. After the cross-section images of the anterior chamber angle were acquired by SS-OCT, SC was confirmed by two independent masked observers and the average area, long diameter, and perimeter of the SC were measured. In normal subjects the circumference, area, and long diameter is 580.34±87.81  μm, 8023.89±1486.10  μm2, and 272.83±49.39  μm, respectively, and these parameters were 393.25±98.04  μm, 3941.50±1210.69  μm2, and 190.91±46.47  μm in the POAG subjects. The area of SC in the normal ones was significantly larger than that in POAG eyes (p<0.001), so as the long diameter and the perimeter (p<0.001; p<0.001).

Interleukin-17A neutralization alleviated ocular neovascularization by promoting M2 and mitigating M1 macrophage polarization

Neovascularization (NV), as a cardinal complication of several ocular diseases, has been intensively studied, and research has shown its close association with inflammation and immune cells. In the present study, the role of interleukin‐17A (IL‐17A) in angiogenesis in the process of ocular NV both in vivo and in vitro was investigated. Also, a paracrine role of IL‐17A was demonstrated in the crosstalk between endothelial cells and macrophages in angiogenesis. In the retinas of mice with retinopathy of prematurity, the IL‐17A expression increased significantly at postnatal day 15 (P15) and P18 during retinal NV. Mice given IL‐17A neutralizing antibody (NAb) developed significantly reduced choroidal NV and retinal NV. Studies on vascular endothelial growth factor (VEGF) over‐expressing mice suggested that IL‐17A modulated NV through the VEGF pathway. Furthermore, IL‐17A deficiency shifted macrophage polarization toward an M2 phenotype during retinal NV with significantly reduced M1 cytokine expression compared with wild‐type controls. In vitro assays revealed that IL‐17A treated macrophage supernatant gave rise to elevated human umbilical vascular endothelial cell proliferation, tube formation and VEGF receptor 1 and receptor 2 expression. Therefore, IL‐17A could potentially serve as a novel target for treating ocular NV diseases. The limitation of this study involved the potential mechanisms, such as which transcription accounted for macrophage polarization and how the subsequent cytokines were modulated when macrophages were polarized. Further studies need to be undertaken to definitively determine the extent to which IL‐17A neutralizing anti‐angiogenic activity depends on macrophage modulation compared with anti‐VEGF treatment.

Microcirculatory Responses to Hyperoxia in Macular and Peripapillary Regions

Purpose To evaluate the hyperoxia response of the retinal vascular system in different parts of the fundus using optical coherence tomography (OCT) angiography. Methods Using an OCT angiography system and a split-spectrum amplitude decorrelation angiography (SSADA) algorithm, perfused vessel density at the macular and peripapillary regions was measured before and after breathing 80% oxygen in 10 healthy Chinese subjects. The repeatability of the hyperoxia response was also tested. Results Hyperoxia provocation caused a significant decrease in retinal perfused vessel density in both the macular and peripapillary areas. The para- and perifoveal area had a mean reduction of 13.66% and 15.17%, respectively; these reductions were significantly greater than in the peripapillary area (9.52%; parafovea versus peripapillary, P = 0.023; perifovea versus peripapillary, P = 0.006). The coefficients of variation (CV), intraclass correlations (ICC), and Bland-Altman plots suggested strong repeatability of the hyperoxia response. Conclusions The optical coherence tomography system, in conjunction with the SSADA algorithm, recorded a significant reduction in retinal perfused vessel density after hyperoxia, and the reduction was greater in the macular area than in the peripapillary area.

Reduced Retinal Vessel Density in Obstructive Sleep Apnea Syndrome Patients: An Optical Coherence Tomography Angiography Study

Purpose To examine the retinal vasculature in patients with obstructive sleep apnea-hypopnea syndrome (OSAS) and to determine the correlation between retinal vascularity and the severity of OSAS. Design Prospective, cross-sectional study. Methods Sixty-nine consecutive subjects who underwent polysomnography were enrolled. Patients were divided into three groups according to the severity of OSAS, which was defined using the apnea-hypopnea index (AHI) as normal-to-mild (AHI <15), moderate (≥15 to <30), or severe (≥30). The vessel densities, and macular and retinal nerve fiber layer thicknesses were compared among the three groups. The correlations between clinical variables (age, heart rate, body mass index, ocular perfusion pressure, spherical equivalence, IOP, inner retinal thickness, and AHI) and vessel densities were also determined. Results The full and inner parafoveal retinal thickness and the retinal nerve fiber layer thickness were similar in all three groups. The retinal vessel density decreased with greater severity of OSAS. The decrease in vessel density differed between the peripapillary and parafoveal areas. The moderate group had a significantly lower vessel density than the normal-to-mild group in the peripapillary area (P < 0.05), but similar vessel density as the normal-to-mild group in the parafoveal area (P > 0.05). The vessel densities in the parafoveal and peripapillary areas were significantly and negatively correlated with AHI (both P < 0.05); the relative reduction in vessel density was greater in the peripapillary area than in the parafoveal area. Conclusions In OSAS patients, the vessel densities in the peripapillary and parafoveal areas decreased with greater disease severity, and the decrease was more prominent in the peripapillary area.

Schlemm's Canal Expansion After Uncomplicated Phacoemulsification Surgery: An Optical Coherence Tomography Study

Purpose To evaluate the effects of phacoemulsification cataract surgery on Schlemms canal (SC) using swept-source optical coherence tomography (OCT). Methods Patients with a senile cataract were included. The SC area and diameter were checked by OCT at the baseline and 1 day, 1 week, 1 month, and 6 months after the cataract surgery. Multivariate linear regression analysis was performed for predictors of change in the mean SC area and diameter. Results Twenty-five eyes (25 patients) were included in the final analysis. After the cataract surgery, there was a significant increase in the SC area and diameter, and a decrease in the intraocular pressure (IOP) (repeated-measures analysis of variance; all P < 0.05), which extended to the end of the follow-up period. After multivariate analysis, the changes in the SC area and diameter 6 months after surgery were correlated with the change in the IOP (SC area, β = -0.575, P < 0.0001; SC diameter, β = -0.576, P < 0.0001) and the change in the anterior vault (AV) (SC area, β = 0.359, P = 0.007; SC diameter, β = 0.413, P = 0.003). Conclusions Expansion of the SC was observed after cataract surgery. The degree of expansion was related to the extent of the decrease in the IOP. Further studies are needed to determine whether these changes will last over a long period of time.

αA-crystallin gene CpG islands hypermethylation in nuclear cataract after pars plana vitrectomy.

PurposeTo investigate the DNA methylation status of αA-crystallin gene in cataract secondary to pars plana vitrectomy.MethodsAnterior capsular membranes of 40 eyes of 40 patients with cataract secondary to vitrectomy were collected. Another 20 eyes of 20 patients who received pars plana vitrectomy and phacoemulsification in the primary procedure, were recruited as control. Methylation status of the CpG islands of αA-crystallin gene was analyzed by pyrosequencing. Expression of αA-crystallin was evaluated by real-time polymerase chain reaction and western blot.ResultsIn the post vitrectomy group, five patients with posterior subcapsular opacity and four patients with cortical opacity were excluded from further analysis. The remaining 31 patients with nuclear cataract were assigned into two groups according to tamponade types: 19 of octafluoropropane (C3F8) and 12 of silicone oil (SiO). The average nuclear color grading was elevated both in C3F8 and SiO groups after vitrectomy. Compared to the control group, hypermethylation of the CpG islands in the αA-crystallin gene promoter was found in both post vitrectomy groups, accompanied by significantly reduced αA-crystallin expression. No statistically significant differences were found between the C3F8 and SiO groups either for DNA methylation status or αA-crystallin expression.ConclusionsCpG islands hypermethylation of αA-crystallin gene may be involved in nuclear cataract formation after pars plana vitrectomy.

Cannabinoids Regulate the Diameter of Pericyte-Containing Retinal Capillaries in Rats

Background/Aims: Cannabinoids are vasoactive substances that act as key regulators of arterial tone in the blood vessels supplying peripheral tissues and the central nervous system. We therefore investigated the effect of cannabinoids on retinal capillaries and pericytes. Methods: The effects of cannabinoids on capillary diameters were determined using an ex vivo whole-mount rat retinal model. Western blotting, quantitative PCR, and immunohistochemistry were performed to explore the underlying mechanism. Results: Endogenous cannabinoid 2-arachidonoylglycerol and anandamide and exogenous cannabinoid (R-(+)-WIN55212-2) dilated the noradrenaline-precontracted capillaries in a concentration-dependent manner (1 µM to 0.1 mM). The extent of vasorelaxation was positively correlated with changes in pericyte width. The effects of R-(+)-WIN55212-2 on vasorelaxation and pericyte width were inhibited by a cannabinoid receptor type-1 (CB1) antagonist, AM251 or rimonabant (SR141716A), the nitric oxide synthase inhibitor l-NAME, and the guanylate cyclase inhibitor ODQ. They were also abolished by the removal of the endothelium, but not by the cannabinoid receptor-2 antagonist SR144528, the endothelial cannabinoid receptor antagonist O-1918, or the cyclooxygenase inhibitor indomethacin. Conclusion: The exogenous cannabinoid R-(+)-WIN55212-2 promotes the vasorelaxation of pericyte-containing rat retinal capillaries. This effect of R-(+)-WIN55212-2 is dependent on CB1 and the nitric oxide–cyclic guanosine monophosphate pathway, and requires an intact endothelium.