Endovenous radiofrequency ablation using a new bipolar electrode in a canine model: a new endovenous radiofrequency electrode

Purpose@#This study aimed to determine the effectiveness and safety of a newly developed endovenous radiofrequency (RF) catheter compared with that of the existing RF catheter in a canine model. @*Methods@#Seven dogs underwent ablation using 1 control catheter (ClosureFAST, CF; Covidien) and 1 experimental catheter (VENISTAR, VS; STARmed Co., Ltd.) in the femoral and cephalic veins. The ablated vein was evaluated macroscopically (2,3,5-triphenyltetrazolium chloride staining, TTC), microscopically (hematoxylin and eosin staining), and ultrasonographically. Vessel injury score was used to evaluate the ablating effect objectively. Veins from 1 dog were evaluated on the day of ablation, while in the remaining 6 dogs, the ablated veins were evaluated 2 weeks later. @*Results@#A total of 23 veins (CF, 11 veins; VS, 12 veins) were ablated in 7 dogs. Non–TTC-stained vein wall areas were identified in all ablated veins. No significant difference was observed in the mean vessel injury score (2.54 ± 1.16 vs. 2.42 ± 1.13, P = 0.656) and the mean vessel wall thickness (0.32 ± 0.03 mm vs. 0.31 ± 0.05 mm, P = 0.212) between CF and VS. There was no blood flow in all veins ablated with VS, whereas there was remaining blood flow in 1 vein ablated with CF. Perivenous complication was not observed. @*Conclusion@#Endovenous RF ablation using a newly developed VS RF catheter seems to provide comparable occlusion rate and degree of vein wall injury without perivenous adverse events compared to the most commonly used RF catheter (CF).

Short-term Efficacy and Safety of XEN Stent Implantation with or without a Conjunctival Incision

Purpose@#Comparison of the 6-month outcomes of ab externo XEN 45 gel stent implantation with conjunctival resection in Korean glaucoma patients. @*Methods@#From January to May 2021, 43 open-angle glaucoma patients who underwent ab externo XEN stent insertion alone and were followed for more than 6 months were classified into incision (n = 23) and non-incision (n = 20) groups according to the presence or absence of a conjunctival incision and analyzed retrospectively. Qualified or complete success was defined as achieving the personal target intraocular pressure (IOP) with or without medication, respectively. @*Results@#The IOP measured 6 months after surgery decreased significantly in both groups. The number of IOP-lowering drugs required was also reduced. The decrease in IOP after surgery was greater in the non-incision group. Six months after surgery, the qualified success rate was 55% in the non-incision group and 52.2% in the incision group, while the complete success rate was 40% and 8.7%, respectively. During follow-up, 58.1% of the patients underwent bleb needling more than once, and 20.9% underwent additional IOP-lowering surgery, but there was no difference between the two groups. @*Conclusions@#XEN stent insertion helped to reduce IOP and the number of IOP-lowering agents after 6 months regardless of a conjunctival incision. However, to maintain the target IOP, bleb manipulation was required in many cases.

Effects of Vascular Endothelial Growth Factor on YAP/TAZ Signaling in Trabecular Meshwork Cells

Purpose@#To investigate the effects of vascular endothelial growth factor (VEGF) on yes-associated protein (YAP)/transcriptional coactivator with a PDZ-binding motif (TAZ), a Hippo pathway-related transcription factor, and the role of YAP/TAZ induced by trabecular meshwork stimulation. @*Methods@#Human trabecular meshwork cells were cultured and treated with various VEGF concentrations to verify cell cytotoxicity using the CCK-8 solution. Transforming growth factor β-2 (TGFβ2; 5 ng/mL) and VEGF (30 ng/mL) were applied and YAP/TAZ expression was assessed by western blotting, reverse transcription quantitative polymerase chain reaction and immunocytochemistry. Fibronectin, collagen 1, and myocilin expression were also assessed by western blotting. The cells were stained using Alexa Fluor 488-phalloidin to observe F-actin changes. @*Results@#YAP and TAZ expression increased following TGFβ2 and VEGF treatment for 24 hours. Fibronectin and collagen 1 increased significantly in all three treatment groups, while myocilin increased in the TGFβ2 and TGFβ2+VEGF groups. The F-actin staining showed increased cross-linking in the trabecular meshwork cells. @*Conclusions@#VEGF induced YAP/TAZ signaling and increased trabecular meshwork cell fibrosis. Based on the functional changes caused by VEGF, it is suggested that VEGF and YAP/TAZ may increase aqueous humor outflow resistance in trabecular meshwork cells.

Intermediate levels of asymptomatic transmission can lead to the highest levels of epidemic fatalities

Asymptomatic infections have hampered the ability to characterize and prevent the transmission of SARS-CoV-2 throughout the ongoing pandemic. Even though asymptomatic infections reduce severity at the individual level, they can make population-level outcomes worse if asymptomatic individuals--unaware they are infected--transmit more than symptomatic individuals. Using an epidemic model, we show that intermediate levels of asymptomatic infection lead to the highest levels of epidemic fatalities when the increase in asymptomatic transmission, due either to individual behavior or mitigation efforts, is strong. We generalize this result to include presymptomatic transmission, showing how intermediate levels of non-symptomatic transmission can lead to the highest levels of fatalities. Finally, we extend our framework to illustrate how the intersection of asymptomatic spread and immunity profiles determine epidemic trajectories, including population-level severity, of future variants.

Inferring the differences in incubation-period and generation-interval distributions of the Delta and Omicron variants of SARS-CoV-2

Estimating the differences in the incubation-period, serial-interval, and generation-interval distributions of SARS-CoV-2 variants is critical to understanding their transmission and control. However, the impact of epidemic dynamics is often neglected in estimating the timing of infection and transmission--for example, when an epidemic is growing exponentially, a cohort of infected individuals who developed symptoms at the same time are more likely to have been infected recently. Here, we re-analyze incubation-period and serial-interval data describing transmissions of the Delta and Omicron variants from the Netherlands at the end of December 2021. Previous analysis of the same data set reported shorter mean observed incubation period (3.2 days vs 4.4 days) and serial interval (3.5 days vs 4.1 days) for the Omicron variant, but the number of infections caused by the Delta variant decreased during this period as the number of Omicron infections increased. When we account for growth-rate differences of two variants during the study period, we estimate similar mean incubation periods (3.8-4.5 days) for both variants but a shorter mean generation interval for the Omicron variant (3.0 days; 95% CI: 2.7-3.2 days) than for the Delta variant (3.8 days; 95% CI: 3.7-4.0 days). We further note that the differences in estimated generation intervals may be driven by the "network effect"--higher effective transmissibility of the Omicron variant can cause faster susceptible depletion among contact networks, which in turn prevents late transmission (therefore shortening realized generation intervals). Using up-to-date generation-interval distributions is critical to accurately estimating the reproduction advantage of the Omicron variant. SignificanceRecent studies suggest that individuals infected with the Omicron variant develop symptoms earlier (shorter incubation period) and transmit faster (shorter generation interval) than those infected with the Delta variant. However, these studies typically neglect population-level effects: when an epidemic is growing, a greater proportion of current cases were infected recently, biasing us toward observing faster transmission events. Accounting for this dynamical bias, we find that Omicron infections from the Netherlands at the end of December 2021 had similar incubation periods, but shorter generation intervals, compared to Delta infections from the same period. Shorter generation intervals of the Omicron variant might be due to its higher effective reproduction number, which can cause faster local susceptible depletion around the contact network.

How time-scale differences in asymptomatic and symptomatic transmission shape SARS-CoV-2 outbreak dynamics

Asymptomatic and symptomatic SARS-CoV-2 infections can have different characteristic time scales of transmission. These time-scale differences can shape outbreak dynamics as well as bias population-level estimates of epidemic strength, speed, and controllability. For example, prior work focusing on the initial exponential growth phase of an outbreak found that larger time scales for asymptomatic vs. symptomatic transmission can lead to under-estimates of the basic reproduction number as inferred from epidemic case data. Building upon this work, we use a series of nonlinear epidemic models to explore how differences in asymptomatic and symptomatic transmission time scales can lead to changes in the realized proportion of asymptomatic transmission throughout an epidemic. First, we find that when asymptomatic transmission time scales are longer than symptomatic transmission time scales, then the effective proportion of asymptomatic transmission increases as total incidence decreases. Moreover, these time-scale-driven impacts on epidemic dynamics are enhanced when infection status is correlated between infector and infectee pairs (e.g., due to dose-dependent impacts on symptoms). Next we apply these findings to understand the impact of time-scale differences on populations with age-dependent assortative mixing and in which the probability of having a symptomatic infection increases with age. We show that if asymptomatic generation intervals are longer than corresponding symptomatic generation intervals, then correlations between age and symptoms lead to a decrease in the age of infection during periods of epidemic decline (whether due to susceptible depletion or intervention). Altogether, these results demonstrate the need to explore the role of time-scale differences in transmission dynamics alongside behavioural changes to explain outbreak features both at early stages (e.g., in estimating the basic reproduction number) and throughout an epidemic (e.g., in connecting shifts in the age of infection to periods of changing incidence).

Direct and indirect mortality impacts of the COVID-19 pandemic in the US, March 2020-April 2021

Excess mortality studies provide crucial information regarding the health burden of pandemics and other large-scale events. Here, we used time series approaches to separate the direct contribution of SARS-CoV-2 infections on mortality from the indirect consequences of pandemic interventions and behavior changes in the United States. We estimated deaths occurring in excess of seasonal baselines stratified by state, age, week and cause (all causes, COVID-19 and respiratory diseases, Alzheimers disease, cancer, cerebrovascular disease, diabetes, heart disease, and external causes, including suicides, opioids, accidents) from March 1, 2020 to April 30, 2021. Our estimates of COVID-19 excess deaths were highly correlated with SARS-CoV-2 serology, lending support to our approach. Over the study period, we estimate an excess of 666,000 (95% Confidence Interval (CI) 556000, 774000) all-cause deaths, of which 90% could be attributed to the direct impact of SARS-CoV-2 infection, and 78% were reflected in official COVID-19 statistics. Mortality from all disease conditions rose during the pandemic, except for cancer. The largest direct impacts of the pandemic were seen in mortality from diabetes, Alzheimers, and heart diseases, and in age groups over 65 years. In contrast, the largest indirect consequences of the pandemic were seen in deaths from external causes, which increased by 45,300 (95% CI 30,800, 59,500) and were statistically linked to the intensity of non-pharmaceutical interventions. Within this category, increases were most pronounced in mortality from accidents and injuries, drug overdoses, and assaults and homicides, while the rate of death from suicides remained stable. Younger age groups suffered the brunt of these indirect effects. Overall, on a national scale, the largest consequences of the COVID-19 pandemic are attributable to the direct impact of SARS-CoV-2 infections; yet, the secondary impacts dominate among younger age groups, in periods of stricter interventions, and in mortality from external causes. Further research on the drivers of indirect mortality is warranted to optimize interventions in future pandemics.

Hydrophilic guidewire usage under ultrasound guidance in facilitating catheter advancement during endovenous treatment of incompetent great saphenous veins

Purpose@#This study was performed To investigate the use of hydrophilic guidewires for facilitating catheter advancement during varicose vein treatment using radiofrequency ablation (RFA) or cyanoacrylate closure (CAC). @*Methods@#From March 2016 to April 2019, 463 limbs of 285 with incompetent great saphenous veins were subjected to RFA (321 limbs of 197 patients) or CAC (142 limbs of 88 patients). Procedure records were reviewed for the use of a hydrophilic guidewire, reason for the guidewire usage, and diameter of the guidewire. @*Results@#A hydrophilic guidewire was used to facilitate catheter advancement to treat 92 of 463 limbs (19.9%). For RFA, a guidewire was used to treat 53 of 321 limbs (16.5%). Among them, 15 limbs (28.3%) had vasospasm, and 38 limbs (71.7%) had venous tortuosity. For CAC, guidewire was used for 39 of 142 limbs (27.5%). Among them, 10 limbs (25.6%) had vasospasm, 23 limbs (59.0%) had venous tortuosity, and 6 limbs (15.4%) had repeated engagement of a J-tip guidewire into the varicose tributaries. In CAC, the frequency of hydrophilic guidewire usage was higher than that in RFA (P = 0.006). All varicose vein treatment sessions were technically successful. @*Conclusion@#Hydrophilic guidewire usage could facilitate catheter advancement when hindered by vasospasm, tortuosity of the saphenous vein, or repeated engagement into the varicose tributaries.

The unmitigated profile of COVID-19 infectiousness

Quantifying the temporal dynamics of infectiousness of individuals infected with SARS-CoV-2 is crucial for understanding the spread of the COVID-19 pandemic and for analyzing the effectiveness of different mitigation strategies. Many studies have tried to use data from the onset of symptoms of infector-infectee pairs to estimate the infectiousness profile of SARS-CoV-2. However, both statistical and epidemiological biases in the data could lead to an underestimation of the duration of infectiousness. We correct for these biases by curating data from the initial outbreak of the pandemic in China (when mitigation steps were still minimal), and find that the infectiousness profile is wider than previously thought. For example, our estimate for the proportion of transmissions occurring 14 days or more after infection is an order of magnitude higher - namely 19% (95% CI 10%-25%). The inferred generation interval distribution is sensitive to the definition of the period of unmitigated transmission, but estimates that rely on later periods are less reliable due to intervention effects. Nonetheless, the results are robust to other factors such as the model, the assumed growth rate and possible bias of the dataset. Knowing the unmitigated infectiousness profile of infected individuals affects estimates of the effectiveness of self-isolation and quarantine of contacts. The framework presented here can help design better quarantine policies in early stages of future epidemics using data from the initial stages of transmission.

Roles of generation-interval distributions in shaping relative epidemic strength, speed, and control of new SARS-CoV-2 variants

Inferring the relative strength (i.e., the ratio of reproduction numbers, [R]var/[R]wt) and relative speed (i.e., the difference between growth rates, rvar -rwt) of new SARS-CoV-2 variants compared to their wild types is critical to predicting and controlling the course of the current pandemic. Multiple studies have estimated the relative strength of new variants from the observed relative speed, but they typically neglect the possibility that the new variants have different generation intervals (i.e., time between infection and transmission), which determines the relationship between relative strength and speed. Notably, the increasingly predominant B.1.1.7 variant may have a longer infectious period (and therefore, a longer generation interval) than prior dominant lineages. Here, we explore how differences in generation intervals between a new variant and the wild type affect the relationship between relative strength and speed. We use simulations to show how neglecting these differences can lead to biases in estimates of relative strength in practice and to illustrate how such biases can be assessed. Finally, we discuss implications for control: if new variants have longer generation intervals then speed-like interventions such as contact tracing become more effective, whereas strength-like interventions such as social distancing become less effective.

Choroidal Thickness in Advanced Glaucoma Patients

Purpose@#We investigated choroidal thickness according to the classification of glaucoma and related factors in patients with advanced glaucoma. @*Methods@#The present study included 133 eyes of 133 advanced glaucoma patients with a mean deviation of <-12 dB. Patients were classified into primary open angle glaucoma (POAG) and normal-tension glaucoma (NTG) groups. Factors related to the subfoveal and peripapillary choroidal thickness were analyzed using linear regression analysis. @*Results@#The mean peripapillary choroid thickness was 99.20 ± 46.85 µm in the NTG group, which was significantly thinner than in the POAG group (121.85 ± 45.39 µm, p = 0.006). Additionally, in the sectoral comparison, the NTG group had thinner choroids than the POAG group in all areas (p < 0.05 for all). In the linear regression analysis, glaucoma class (p = 0.007), age (p = 0.005), and intraocular pressure (IOP) (p = 0.024) significantly affected the peripapillary choroid thickness. Moreover, age (p = 0.029) and macular thickness (p = 0.002) were significantly associated with subfoveal choroid thickness. @*Conclusions@#In advanced glaucoma, low baseline IOP, NTG, and old age were significantly associated with a thin peripapillary choroid, suggesting an association between thin peripapillary choroid and the etiology of NTG. Further studies are needed to clarify the significance of a thin choroid in the pathogenesis of glaucoma.

Cutaneous Mycobacterium massiliense Infection Caused by Skin Coining ‘Gua Sha’ in Korean Healthy Female

Nontuberculous mycobacteria are ubiquitous environmental organisms that are rare pathogens in immunocompetent individuals. However, cutaneous nontuberculous mycobacteria infections have been increasingly associated with invasive procedures, including surgery, liposuction, filler injection, intramuscular injection, mesotherapy, piercing, acupuncture, and cupping therapy. Herein, we report the first case of cutaneous nontuberculous mycobacteria infection caused by the East-Asian traditional treatment ‘Gua Sha’, also known as scraping, coining or spooning in English. A 35-year-old healthy female presented with widespread, painful skin nodules and pustules on her upper and lower extremities that had developed after Gua Sha treatment for body contouring. Histopathologic examination of the lesions revealed granulomatous inflammation in the dermis and the culture isolates were identified as Mycobacterium massiliense with molecular identification. The patient was successfully treated with intermittent incision and drainage of persistent nodules and oral clarithromycin based on antimicrobial susceptibility testing. We recommend implementation of a standard safety protocol for Gua Sha practitioners to minimize the risk of infection transmission.

Difference in Vitamin D Levels Between Children with Clostridioides difficile Enteritis and Those with Other Acute Infectious Enteritis / 대한소아소화기영양학회지

Purpose@#A steady increase in Clostridioides difficile enteritis (CDE) has been reported recently.CDE is associated with intestinal dysbiosis, and vitamin D receptors are known to play an important role in this microbial imbalance as immunological regulators. We investigated the difference in vitamin D levels between children with CDE and those with other acute infectious enteritis. @*Methods@#This retrospective study was conducted on children below 18 years of age who visited the Gil hospital, underwent investigation to assess vitamin D levels, and had confirmed gastrointestinal infection between January 2015 and December 2018. Patients were divided into two groups: the “CDE group” (n=18) and the “other infectious enteritis group” (n=88); their clinical characteristics, other laboratory results, and vitamin D levels were analyzed. @*Results@#There was no difference in gender, age, and seasonal distributions between the CDE and other infectious enteritis groups. Other laboratory results were not significantly different between two groups, excluding serum albumin level (4.52±0.45 g/dL vs. 4.31±0.28 g/dL, p=0.011). The mean 25-hydroxy vitamin D level in the CDE group was higher than that in the control group (18.75±8.11 ng/mL vs. 14.50±6.79 ng/mL, p=0.021). @*Conclusion@#Vitamin D levels in the CDE group were lower than normal but higher than the other infectious enteritis group. These results suggested that CDE has a different mechanism or susceptibility associated with vitamin D in children, and even marginal changes in vitamin D levels can act as a risk factor for infection.

Methodology and Rationale for Ophthalmic Examinations in the Seventh and Eighth Korea National Health and Nutrition Examination Surveys (2017–2021)

This report provides a detailed description of the methodology for ophthalmic examinations according to the Korea National Health and Nutrition Examination Survey (KNHANES) VII and VIII (from 2017 to 2021). The KNHANES is a nationwide survey which has been performed since 1998 in representatives of whole Korean population. During the KNHANES VII and VIII, in addition to the ophthalmic questionnaire, intraocular pressure measurement, visual field test, auto refractometry, axial length and optical coherence tomography measurements were included. This new survey will provide not only provide normative and pathologic ophthalmic data including intraocular pressure, refractive error, axial length, visual field and precise measurement of anterior segment, macula and optic nerve with optical coherence tomography, but also a more accurate diagnosis for major adult blindness diseases, including age-related macular degeneration, diabetic retinopathy, glaucoma, and other ocular diseases, for the national Korean population.

Current Strategy in Endovascular Management for Below-the-Knee Arterial Lesions

The below-the-knee arterial tree is the thinnest of all the leg vessels and is an important path for blood flow to the foot. Hence, lesions including stenosis, especially obstruction, may lead to critical limb ischemia which represents the most severe clinical manifestation of peripheral arterial disease. It is characterized by the presence of ischemic rest pain, ischemic lesions, or gangrene attributable to the objectively proven arterial occlusive disease. Typically, the atherosclerotic disease process involving the below-the-knee arterial tree is diffuse in the majority of patients. The cornerstone of therapy is vascular reconstruction and limb salvage. Revascularization should be attempted whenever technically possible, without delay, in patients presenting critical limb ischemia and when the clinical status is not hopelessly non-ambulatory. Therefore, endovascular treatment can become the gold standard for the full range of patients including below-the-knee, limiting the clinical role of the classically trained surgeons.

Characteristics of Visual Field Defects in Korean Advanced Glaucoma

Purpose@#We investigated the clinical characteristics of visual field (VF) defects in Korean advanced glaucoma patients. @*Methods@#The present study included 109 eyes of 109 advanced glaucoma patients whose mean deviation (MD) is under -12 dB. The subjects were classified into primary open angle glaucoma (POAG) and normal tension glaucoma (NTG) group. Average numeric decibel in each VF points were visualized with color topographic image and dot graph image using python 3.5. VF was divided into four quadrants or two half fields, and the differences in the degree of VF defects in each locations were assessed with raw decibel data. Additionally, mean sensitivity of central 12 points were compared between the two groups. @*Results@#Generally the features of VF defects were severely depressed VF sensitivity at the superonasal quadrant and relatively preserved central area and inferotemporal quadrant in both of the glaucoma groups. But we found the extent of deflection for VF defect in the NTG eyes was higher than that of the POAG eyes (p < 0.05). The POAG eyes tended to show more diffuse and evenly distributed VF defect, whereas NTG eyes tended to have more severely depressed VF at the superonasal quadrant and relatively preserved VF at the inferotemporal quadrant. There was no significant difference in the degree of central VF defects between the two groups. @*Conclusions@#The characteristics of VF defect in Korean advanced glaucoma revealed different features based on the glaucoma diagnosis. The POAG eyes tended to show diffuse VF defects, whereas NTG eyes tended to have more severely depressed VF sensitivity at the superonasal quadrant and relatively preserved VF at the inferotemporal quadrant.

Clinical Evaluation of Unilateral Open-Angle Glaucoma: A Two-Year Follow-Up Study / 전남의대학술지

To evaluate the clinical characteristics of unilateral open-angle glaucoma, patients diagnosed with unilateral open-angle glaucoma from January 2017 to October 2018 were divided into primary open-angle glaucoma and normal-tension glaucoma groups according to the type of glaucoma diagnosed. The glaucoma and the contralateral eyes were compared, and the contralateral eye was analyzed for conversion to glaucoma and its risk factors were assessed during the 2-year follow-up period. Among 99 patients, 36 were diagnosed with primary open-angle glaucoma and 63 with normal-tension glaucoma. When comparing the glaucoma eye with the contralateral eye, the visual field mean deviation value (all p<0.001), peripapillary retinal nerve fiber layer thickness (all p<0.001), macular ganglion cell layer-inner plexiform layer thickness (p< 0.001, p=0.003), and optic nerve cup-disc ratio (p=0.005, p<0.001) were significantly different in both the primary open-angle glaucoma and normal-tension glaucoma groups. In normal-tension glaucoma, peripapillary retinal nerve fiber layer thickness was significantly thinner in the glaucoma conversion group than in the glaucoma non-conversion group (p=0.008). It was significantly associated with glaucoma conversion (odds ratio=0.97, p=0.023). In conclusion, in patients with unilateral open-angle glaucoma, the contralateral eye may develop glaucoma. In particular, if the peripapillary retinal nerve fiber layer thickness is decreased in normal-tension glaucoma, the possibility of glaucoma conversion is high; hence, careful examination is required.

Difference in Vitamin D Levels Between Children with Clostridioides difficile Enteritis and Those with Other Acute Infectious Enteritis / 대한소아소화기영양학회지

Purpose@#A steady increase in Clostridioides difficile enteritis (CDE) has been reported recently.CDE is associated with intestinal dysbiosis, and vitamin D receptors are known to play an important role in this microbial imbalance as immunological regulators. We investigated the difference in vitamin D levels between children with CDE and those with other acute infectious enteritis. @*Methods@#This retrospective study was conducted on children below 18 years of age who visited the Gil hospital, underwent investigation to assess vitamin D levels, and had confirmed gastrointestinal infection between January 2015 and December 2018. Patients were divided into two groups: the “CDE group” (n=18) and the “other infectious enteritis group” (n=88); their clinical characteristics, other laboratory results, and vitamin D levels were analyzed. @*Results@#There was no difference in gender, age, and seasonal distributions between the CDE and other infectious enteritis groups. Other laboratory results were not significantly different between two groups, excluding serum albumin level (4.52±0.45 g/dL vs. 4.31±0.28 g/dL, p=0.011). The mean 25-hydroxy vitamin D level in the CDE group was higher than that in the control group (18.75±8.11 ng/mL vs. 14.50±6.79 ng/mL, p=0.021). @*Conclusion@#Vitamin D levels in the CDE group were lower than normal but higher than the other infectious enteritis group. These results suggested that CDE has a different mechanism or susceptibility associated with vitamin D in children, and even marginal changes in vitamin D levels can act as a risk factor for infection.

Methodology and Rationale for Ophthalmic Examinations in the Seventh and Eighth Korea National Health and Nutrition Examination Surveys (2017–2021)

This report provides a detailed description of the methodology for ophthalmic examinations according to the Korea National Health and Nutrition Examination Survey (KNHANES) VII and VIII (from 2017 to 2021). The KNHANES is a nationwide survey which has been performed since 1998 in representatives of whole Korean population. During the KNHANES VII and VIII, in addition to the ophthalmic questionnaire, intraocular pressure measurement, visual field test, auto refractometry, axial length and optical coherence tomography measurements were included. This new survey will provide not only provide normative and pathologic ophthalmic data including intraocular pressure, refractive error, axial length, visual field and precise measurement of anterior segment, macula and optic nerve with optical coherence tomography, but also a more accurate diagnosis for major adult blindness diseases, including age-related macular degeneration, diabetic retinopathy, glaucoma, and other ocular diseases, for the national Korean population.

Current Strategy in Endovascular Management for Below-the-Knee Arterial Lesions

The below-the-knee arterial tree is the thinnest of all the leg vessels and is an important path for blood flow to the foot. Hence, lesions including stenosis, especially obstruction, may lead to critical limb ischemia which represents the most severe clinical manifestation of peripheral arterial disease. It is characterized by the presence of ischemic rest pain, ischemic lesions, or gangrene attributable to the objectively proven arterial occlusive disease. Typically, the atherosclerotic disease process involving the below-the-knee arterial tree is diffuse in the majority of patients. The cornerstone of therapy is vascular reconstruction and limb salvage. Revascularization should be attempted whenever technically possible, without delay, in patients presenting critical limb ischemia and when the clinical status is not hopelessly non-ambulatory. Therefore, endovascular treatment can become the gold standard for the full range of patients including below-the-knee, limiting the clinical role of the classically trained surgeons.