Mizuho Mitamura

Human injuries caused by Hokkaido brown bears have been described in fragmented public and clinical records. We conducted a retrospective descriptive public record cohort study of Hokkaido brown bear attack episodes from 2019 to 2024, supplemented by linked clinical records for selected episodes. The primary aim was to characterize publicly recorded episodes and victims; exploratory analyses compared fatal episode proportions by attack time grouping and broad activity context, and the linked clinical subset was used for descriptive clinical characterization only. Among 28 episodes involving 36 victims, seven (25.0%) were fatal. At the victim level, 17 injuries were minor, 12 severe, and seven fatal. Fatal episodes occurred in seven of 16 solo-coded episodes (43.8%) and none of 11 group-coded episodes (0.0%; two-sided Fisher exact P = 0.0216), an exploratory, noncausal association. Seven victims from five episodes were linked to clinical records. Their injuries included complex craniofacial and soft tissue trauma, ocular injury, open fractures, major vascular injury, and thoracic trauma; all received plastic and reconstructive surgical care, with additional specialty involvement in selected cases. This study describes recent Hokkaido brown bear attack episodes using a public record cohort with transparent source documentation and linked clinical details for selected cases. Because of the small number of episodes, potential public record ascertainment bias, and the nonrepresentative clinical subset, the findings should be interpreted descriptively and as hypothesis generating.

Background: Indolent, nonprogressive, multifocal choroidal lesions (INMCLs) are low-grade B-cell lymphoid infiltration with a good visual prognosis, yet their impact on choroidal circulation remains poorly understood. Clinical Significance: We report two cases of INMCLs evaluated via multimodal imaging, focusing on circulatory dynamics using laser speckle flowgraphy (LSFG). Case Presentation: Two patients (a 71-year-old female and a 54-year-old male) with histories of glaucoma presented with multiple yellow-white choroidal lesions at the posterior pole. Optical coherence tomography revealed extensive hyporeflective choroidal spaces in the outer choroid, while indocyanine green angiography (ICGA) showed corresponding hypofluorescent spots. Significantly, LSFG demonstrated regional reduction in LSFG signal, visualized as a “cold colour” pattern extending from the optic disc to the macula. Although both patients exhibited glaucomatous visual field changes, the extent to which INMCL contributed to the paracentral defects remains uncertain and difficult to separate from advanced glaucomatous damage. The clinical findings remained stable over several years without treatment. Conclusions: Our multimodal analysis leads to the tentative hypothesis that INMCLs may be associated with choroidal circulation disturbances, which could putatively stem from mechanical vascular compression due to localized lymphocyte accumulation. These cases highlight the potential utility of longitudinal LSFG in monitoring regional choroidal hemodynamics in INMCL, although its capability to differentiate INMCLs from other choroidal infiltrative diseases warrants validation in future comparative cohorts.

Background and Clinical Significance: Tumors of the lacrimal drainage system are rare but clinically important diagnostic pitfalls because they may mimic benign lacrimal drainage obstruction, chronic dacryocystitis, or sinonasal disease. Pleomorphic adenoma (PA) in this region is exceptionally rare, and delayed recognition may allow progressive extension into adjacent structures. Case Presentation: A 51-year-old woman presented with left nasal obstruction 16 years after external dacryocystorhinostomy for presumed lacrimal drainage obstruction. Examination showed a firm left lacrimal sac mass, proptosis, mild ocular motility limitation, and an intranasal mass. Computed tomography and magnetic resonance imaging showed a large lesion centered in the lacrimal sac region and extending into the nasolacrimal duct, nasal cavity, and maxillary sinus, with orbital displacement. Preoperative biopsy showed epithelial neoplastic tissue without definitive malignant features, but low-grade epithelial malignancy could not be excluded. Complete en bloc excision and medial/inferior orbital wall reconstruction with an autologous calvarial outer table bone graft were performed. The tumor measured 55 × 35 × 25 mm. Final histopathology confirmed PA without malignant transformation. At 2 years postoperatively, there was no recurrence, and proptosis and ocular motility limitation had improved. Conclusions: This case illustrates two diagnostic pitfalls: an underlying tumor may masquerade as lacrimal drainage obstruction, whereas a large benign PA may clinically and radiologically mimic malignancy. Long-standing or atypical unilateral lacrimal symptoms should prompt consideration of tumors and selected use of imaging and tissue diagnosis before lacrimal drainage surgery.

Background/Objectives: To investigate the impact of pachychoroid on the clinical features of neovascular age-related macular degeneration (nAMD) in Japan using the deep learning-based Hokkaido University pachychoroid index (HUPI), which has a high discriminative ability for pachychoroid. Methods: This retrospective observational study examined 124 eyes of 111 treatment-naïve nAMD patients, including 44 eyes with type 1 macular neovascularization (MNV), 26 eyes with type 2 MNV, and 54 eyes with polypoidal choroidal vasculopathy (PCV). HUPI was calculated for each eye from EDI-OCT choroidal images using our modified LeNet that had learned the image patterns of pachychoroid. Differences in HUPI between nAMD types and inter-relationships between nAMD parameters, including HUPI, were evaluated. Results: The mean HUPI was 0.53 ± 0.30 for type 1 MNV, 0.33 ± 0.23 for type 2 MNV, and 0.61 ± 0.3 for PCV, with significant differences between any two of the three groups (p < 0.05, for each). Round-robin multiple regression analysis for nAMD parameters showed the close associations of the HUPI with choroidal vascular hyperpermeability (CVH) and subretinal fluid (SRF) (p = 0.017 and p < 0.001 for each) and the clear division of nAMD parameters into the following two groups: one including intraretinal fluid and type 1 and type 2 MNV and the other including SRF, CVH, polypoidal lesions, and HUPI. Conclusions: HUPI revealed that eyes with type 1 MNV and PCV had more pachychoroid-like features than eyes with type 2 MNV. HUPI was tightly associated with CVH and SRF but not MNV per se in nAMD parameters, reinforcing the pathoetiological concept of differentiating pachychoroid from typical nAMD.

Background/Objectives: The aim of this study was to determine artificial intelligence-based macular fluid (MF) parameters in diabetic macular edema (DME) with optical coherence tomography (OCT) and examine stage-by-stage differences in MF parameters and their relationship with best-corrected visual acuity (BCVA). Methods: This study enrolled 104 eyes with treatment-naïve DME. Intraretinal fluid (IRF) and subretinal fluid (SRF) were detected in horizontal OCT images based on the “Hokkaido University MF segmentation model” when DME was first observed together with BCVA testing. The MF area, the mean brightness, and the variance of brightness were compared between mild or moderate non-proliferative diabetic retinopathy (mNPDR, n = 33), severe NPDR (sNPDR, n = 52), and PDR eyes (n = 19). Correlations between logMAR BCVA and MF parameters were also examined. Results: All the MF parameters tended to increase with DR stages. Especially, the mean brightness of IRF was significantly greater in PDR than in mNPDR. The variance of brightness of IRF increased in sNPDR compared to mNPDR, whereas that of SRF increased in PDR compared to sNPDR. LogMAR BCVA showed positive correlations with MF areas and the variance of brightness of SRF. Conclusions: The qualitative and quantitative MF parameters may be useful for better understanding DME pathogenesis according to DR progression.

Background/Objectives: The purpose of this study was to analyze relevant areas in acute-stage fluorescein angiography (FA) images, predicting the long-term visual prognosis of branch retinal vein occlusion (BRVO) based on gradient-weighted class activation mapping (Grad-CAM). Methods: This retrospective observational study included 136 eyes with BRVO that were followed up for more than a year post-FA. Cropped grayscale images centered on the fovea (200 × 200 pixels) were manually pre-processed from early-phase FA at the acute phase. Pairs of the cropped FA images and the best-corrected visual acuity (BCVA) in remission at least one year post-FA were used to train a 38-layer ResNet with five-fold cross-validation. Correlations between the ResNet-predicted and true (actually measured) logMAR BCVAs in remission, and between the foveal avascular zone (FAZ) area measured by ImageJ (version 1.52r) from FA images and true logMAR BCVA in remission were evaluated. The heat maps generated by Grad-CAM were evaluated to determine which areas were consumed as computational resources for BCVA prediction. Results: The correlation coefficient between the predicted and true logMAR BCVAs in remission was 0.47, and that between the acute-stage FAZ area and true logMAR BCVA in remission was 0.42 (p < 0.0001 for both). The Grad-CAM-generated heat maps showed that retinal vessels adjacent to the FAZ and the FAZ per se had high selectivity (95.7% and 62.2%, respectively). Conclusions: The Grad-CAM-based analysis demonstrated FAZ-neighboring vessels as the most relevant predictor for the long-term visual prognosis of BRVO.