Background/Aims: Krebs von den Lungen-6 (KL-6) is associated with prognosis in patients with COVID-19. However, there is limited data on the correlation between the prognosis of COVID-19 and varying KL-6 levels at different time points. We investigated the optimal cutoff values of the initial and peak serum KL-6 levels to predict mortality and evaluated their correlation with mortality. Methods: This retrospective cohort study collected data on serially collected serum KL-6 levels in patients hospitalized with COVID-19 between October 2020 and January 2022 at a single tertiary hospital in South Korea. The area under the receiver operating characteristic curve and Youden index were used to determine the cutoff points for the initial and peak KL-6 levels that best predicted 30-day mortality. The association between the initial and peak KL-6 values was assessed by univariate and multivariate logistic regression models. Results: A total of 349 patients were included in this study. The mean initial and peak KL-6 levels were significantly higher in the non-survivor group than in the survivor group. The initial and peak KL-6 values that best predicted 30-day mortality were 491.85 U/mL and 660.05 U/mL, respectively. An initial KL-6 level greater than 491.85 U/mL and a peak KL-6 level greater than 660.05 U/mL were significantly associated with 30-day mortality. Conclusions The initial and peak levels of KL-6 were significantly associated with 30-day mortality in hospitalized patients with COVID-19. These findings suggest that serially monitoring blood KL-6 levels could be a valuable prognostic indicator for COVID-19.

Background/Aims: Atrial fibrillation (AF) significantly contributes to global morbidity and mortality. Paroxysmal atrial fibrillation (PAF) is particularly common among patients with cryptogenic strokes or transient ischemic attacks and has a silent nature. This study aims to develop reliable artificial intelligence (AI) algorithms to detect early signs of AF in patients with normal sinus rhythm (NSR) using a 12-lead electrocardiogram (ECG). Methods: Between 2013 and 2020, 552,372 ECG traces from 318,321 patients were collected and split into training (n = 331,422), validation (n = 110,475), and test sets (n = 110,475). Deep neural networks were then trained to predict AF onset within one month of NSR. Model performance was evaluated using the area under the receiver operating characteristic curve (AUROC). An explainable AI technique was employed to identify the inference evidence underlying the predictions of deep learning models. Results: The AUROC for early diagnosis of PAF was 0.905 ± 0.007. The findings reveal that the vicinity of the T wave, including the ST segment and S-peak, significantly influences the ability of the trained neural network to diagnose PAF. Additionally, comparing the summarized ECG in NSR with those in PAF revealed that nonspecific ST-T abnormalities and inverted T waves were associated with PAF. Conclusions Deep learning can predict AF onset from NSR while detecting key features that influence decisions. This suggests that identifying undetected AF may serve as a predictive tool for PAF screening, offering valuable insights into cardiac dysfunction and stroke risk.

Purpose: To investigate the clinical characteristics of South Korean patients with pericentral retinitis pigmentosa (RP) and to identify clinical biomarkers associated with rapid visual acuity decline based on baseline factors. Methods: This retrospective study included 59 eyes of 31 patients diagnosed with pericentral RP. Comprehensive ophthalmological examinations and genetic sequencing were conducted to assess the baseline characteristics. For biomarker analysis, eyes were categorized into two groups based on the annual rate of change in visual acuity. The clinical findings of the two groups were evaluated to identify the biomarkers associated with rapid loss of visual acuity. Results: Patients with pericentral RP in this study exhibited a mean best-corrected visual acuity of 0.17 ± 0.23 in logarithm of the minimum angle of resolution. The visual field test showed annular or semicircular scotoma with relatively preserved periphery and 27 eyes (45.8%) exhibited no macular complications in optical coherence tomography. Genetic analysis identified genes associated with previous typical and pericentral RP studies but also highlighted that many genetic causes of pericentral RP remain unidentified. Of the 55 eyes for which the rate of visual acuity change could be estimated, 18 exhibited an annual decline of ≥10%, whereas 37 showed an annual decline of <10%. Male sex and prolonged b-wave latency on dark-adapted 0.01 electroretinogram correlated with rapid visual acuity decline in the multivariate analysis. Conclusions South Korean patients with pericentral RP exhibited a milder phenotype compared to typical RP patients reported in previous studies. Genetic analysis revealed heterogeneity, with mutations in some genes commonly associated with milder forms of RP. Male sex and prolonged b-wave latency on dark-adapted 0.01 electroretinogram were significant biomarkers for predicting rapid visual acuity decline. Monitoring initial b-wave latency is important for predicting visual decline, particularly in male patients with pericentral RP.

Purpose: To evaluate the long-term efficacy, safety, and prognostic factors of pulsed-light accelerated corneal collagen cross-linking (A-CXL) with continuous riboflavin application to halt keratoconus progression Methods: A-CXL with retention ring-assisted continuous riboflavin application for either 10 or 5 minutes was performed in 37 eyes of 33 patients with progressive keratoconus between 2016 and 2020. Successful halting rates and prognostic factors of time-dependent changes in keratometric values, visual acuity, refractive errors, topographic indices, central corneal thickness, thinnest corneal thickness, irregularity at 3- and 5-mm zone, and endothelial cell density were evaluated. Results: Survival analysis showed successful halting rates of 71% and 89% in A-CXL with 5- and 10-minute–applied riboflavin, respectively. Best-corrected visual acuity significantly improved after A-CXL in both groups. Maximum keratometry decreased significantly from 52.52 to 50.39 diopters (p < 0.001) in the 10-minute group, while there was no significant decrease in the 5-minute group (52.77–51.80 diopters, p = 0.146). irregularity in 3- and 5-mm zone decreased significantly in the 10-minute group, while there was no difference in 5-minute group. Central corneal thickness and thinnest corneal thickness did not differ, and endothelial cell density changes were within acceptable ranges in both groups before and after the surgery. Among keratometric values, keratometric astigmatism was significantly related to posttreatment corneal flattening effect in multivariate regression analysis. Conclusions A-CXL with continuous riboflavin application for 10 minutes is an effective and safe treatment for preventing keratoconus progression. In addition, higher corneal astigmatism showed greater posttreatment corneal flattening effect in successfully treated patients.

It is difficult to determine a cause of bile duct stricture and dilatation. Eosinophilic cholangitis, a rare benign condition, may be one cause of bile duct stricture and dilatation. It can be evaluated using various methods of histopathology, radiographs, endoscopy, and hematologic findings. Treatment generally involves steroid therapy which can lead to improvement. This case report will discuss eosinophilic cholangitis, emphasizing that while it can easily be overlooked but should be considered in differential diagnoses.

Purpose: To investigate the clinical characteristics of South Korean patients with pericentral retinitis pigmentosa (RP) and to identify clinical biomarkers associated with rapid visual acuity decline based on baseline factors. Methods: This retrospective study included 59 eyes of 31 patients diagnosed with pericentral RP. Comprehensive ophthalmological examinations and genetic sequencing were conducted to assess the baseline characteristics. For biomarker analysis, eyes were categorized into two groups based on the annual rate of change in visual acuity. The clinical findings of the two groups were evaluated to identify the biomarkers associated with rapid loss of visual acuity. Results: Patients with pericentral RP in this study exhibited a mean best-corrected visual acuity of 0.17 ± 0.23 in logarithm of the minimum angle of resolution. The visual field test showed annular or semicircular scotoma with relatively preserved periphery and 27 eyes (45.8%) exhibited no macular complications in optical coherence tomography. Genetic analysis identified genes associated with previous typical and pericentral RP studies but also highlighted that many genetic causes of pericentral RP remain unidentified. Of the 55 eyes for which the rate of visual acuity change could be estimated, 18 exhibited an annual decline of ≥10%, whereas 37 showed an annual decline of <10%. Male sex and prolonged b-wave latency on dark-adapted 0.01 electroretinogram correlated with rapid visual acuity decline in the multivariate analysis. Conclusions South Korean patients with pericentral RP exhibited a milder phenotype compared to typical RP patients reported in previous studies. Genetic analysis revealed heterogeneity, with mutations in some genes commonly associated with milder forms of RP. Male sex and prolonged b-wave latency on dark-adapted 0.01 electroretinogram were significant biomarkers for predicting rapid visual acuity decline. Monitoring initial b-wave latency is important for predicting visual decline, particularly in male patients with pericentral RP.

Purpose: To evaluate the long-term efficacy, safety, and prognostic factors of pulsed-light accelerated corneal collagen cross-linking (A-CXL) with continuous riboflavin application to halt keratoconus progression Methods: A-CXL with retention ring-assisted continuous riboflavin application for either 10 or 5 minutes was performed in 37 eyes of 33 patients with progressive keratoconus between 2016 and 2020. Successful halting rates and prognostic factors of time-dependent changes in keratometric values, visual acuity, refractive errors, topographic indices, central corneal thickness, thinnest corneal thickness, irregularity at 3- and 5-mm zone, and endothelial cell density were evaluated. Results: Survival analysis showed successful halting rates of 71% and 89% in A-CXL with 5- and 10-minute–applied riboflavin, respectively. Best-corrected visual acuity significantly improved after A-CXL in both groups. Maximum keratometry decreased significantly from 52.52 to 50.39 diopters (p < 0.001) in the 10-minute group, while there was no significant decrease in the 5-minute group (52.77–51.80 diopters, p = 0.146). irregularity in 3- and 5-mm zone decreased significantly in the 10-minute group, while there was no difference in 5-minute group. Central corneal thickness and thinnest corneal thickness did not differ, and endothelial cell density changes were within acceptable ranges in both groups before and after the surgery. Among keratometric values, keratometric astigmatism was significantly related to posttreatment corneal flattening effect in multivariate regression analysis. Conclusions A-CXL with continuous riboflavin application for 10 minutes is an effective and safe treatment for preventing keratoconus progression. In addition, higher corneal astigmatism showed greater posttreatment corneal flattening effect in successfully treated patients.

It is difficult to determine a cause of bile duct stricture and dilatation. Eosinophilic cholangitis, a rare benign condition, may be one cause of bile duct stricture and dilatation. It can be evaluated using various methods of histopathology, radiographs, endoscopy, and hematologic findings. Treatment generally involves steroid therapy which can lead to improvement. This case report will discuss eosinophilic cholangitis, emphasizing that while it can easily be overlooked but should be considered in differential diagnoses.