Changes of retinal vessel density in low to moderate myopic eyes with orthokeratology evaluated by optical coherence tomography angiography

AIM:To explore the effect of orthokeratology(OK)fitting on retinal vessel density in low to moderate myopia adolescents by using optical coherence tomography angiography.METHODS:Children aged 10 to 14y with a cycloplegic spherical equivalent refraction of−0.50 diopter(D)to−5.00 D and astigmatism with more than−1.50 D were recruited.The enrolled adolescents were divided into OK group and spectacle group.During regular followup,adolescents were measured respectively at pre-wear,1,3,and 6mo after treatment.The follow-up included uncorrected distance visual acuity(UDVA),axial length(AL),superficial capillary plexus density(SCPD),deep capillary plexus density(DCPD),central retinal thickness(CRT),foveal avascular zone area(FAZ-A),foveal avascular zone perimeter(FAZ-P)and foveal vessel density in a 300-μmwide region around foveal avascular zone(FD-300).The collected data were analyzed using statistical methods.RESULTS:By one month,SCPD significantly increased in the fovea and superior retina,and DCPD significantly increased inferiorly in OK group compared to spectacle group(P<0.05).By three months,there were significant increases in SCPD in the fovea and inferior retina,and DCPD in the parafovea,superior,and inferior retina in OK group(P<0.05),while the increase in SCPD and DCPD in the fovea were observed by six months(P<0.05).The FD-300 significantly increased at every follow-up in OK group compared to spectacle group(P<0.05).No significant differences in the CRT,FAZ-A and FAZ-P and FD-300 were observed between two groups(P>0.05).OK group showed a significant improvement in UDVA after wearing OK,compared to spectacle group(P<0.01),while the AL did not show a significant difference between two groups(P>0.05).CONCLUSION:Short-term OK worn can increase local retinal vessel density in adolescents with low-to-moderate myopia.

Cardiopulmonary bypass induced microcirculatory injury of the small bowel in rats

AIM： To investigate microvascular injury quantitatively in the small bowel with respect to cardiopulmonary bypass （CPB） and related mechanisms. METHODS： In 10 male SD rats, normothermic CPB was established and continued with a flow rate of 100-150 mL/kg per minute for 60 min, while another 10 sham-operated animals served as controls. An approximate 10-cm loop of the terminal ileum was exteriorized for observation by means of intravital fluorescence microscopy. The small bowel microcirculatory network including arterioles, capillaries, and collecting venules was observed prior to CPB, CPB 30 min, CPB 60 min, post-CPB 60 min and post-CPB 120 rain. The intestinal capillary perfusion, microvascular permeability and leukocyte adherence were also measured. RESULTS： The systemic hemodynamics remained stable throughout the experiment in both groups. In CPB animals, significant arteriolar vasoconstriction, blood velocity reduction and functional capillary density diminution were found. As concomitances, exaggerated albumin extravasation and increased leukocyte accumulation were also noted. These changes were more pronounced and there were no signs of restitution at the end of the observation period. CONCLUSION： CPB induces significant microcirculatory injury of the small bowel in rats. The major underlying mechanisms are blood flow redistribution and generalized inflammatory response associated with CPB.

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.

Associated risk factors in the early stage of diabetic retinopathy

Background:To investigate the retinal capillary density(RCD)of the macula using optical coherence tomography angiography(OCT-A)in type 2 diabetic patients and to further determine the association with risk factors.Methods:A total of 212 eyes from 212 subjects were recruited;subjects included diabetics with no retinopathy(NDR,n=90 eyes),diabetics with mild retinopathy DR(MDR,n=36 eyes),and healthy participants(Control,n=86 eyes).All participants underwent OCT-A scanning.RCD was quantified by superficial and deep retinal capillary layers(SRCL and DRCL)from OCT-A images.Results:RCD in SRCL and DRCL was lower in NDR(P<0.001)as well as in MDR(P<0.001)when compared with control eyes.Diabetic patients were subdivided according to individual risk factors,complications related to diabetes,and hyperglycemia.Diabetic patients showed lower RCD in both the SRCL and DRCL when compared with healthy controls.Diabetics with age>55y,HbA1c>7%had significantly reduced DRCL(P<0.05)when compared with the other group of diabetics(age<55y,HbA1c<7%).Diabetics with a blood urea nitrogen(BUN)>8.2 mmol/L had significantly reduced SRCL and DRCL when compared to the other group of diabetics.Conclusions:Risk factors including older age,higher level of HbA1c,LDL-C and BUN,were associated with lower RCDs found in type 2 diabetic patients with and without mild DR by OCT-A.The impairment of retinal capillary by OCT-A may play a key role in the early monitoring of management in diabetes.