Topcon (Japan)

To evaluate parameters measured using the tear film imager (TFI) prototype, a new technology that enables to quantify the tear film thickness of lipid and mucoaqueous layers. In this cross-sectional study, patients with dry eye, meibomian gland dysfunction (MGD), and non-dry eye/MGD from February 2020 to January 2021 were analyzed. Quantified TFI outputs included lipid layer thickness (LLT), mucoaqueous layer thickness (MALT), MALT rate of change (MALTR), and lipid breakup time. Two other interferometry devices, LipiView2 and DR-1α, were used for comparison. TFI outputs and other clinical parameters were analyzed using correlation coefficients. Each patient underwent one or several study visits. Baseline values of three device outputs, other clinical parameters, and their changes were examined. This study involved 28 patients (8 patients with dry eyes, 13 with MGD, and 7 with non-dry eye/MGD). Baseline TFI, LipiView2, and DR-1α values were associated with various clinical parameters. The LLT values estimated using TFI had a correlation with the plugging score in the upper eyelid (r=-0.42). Several TFI values have correlated better than LipiView2 and DR-1α, particularly with questionnaire scores. MALTR by TFI revealed a correlation between standardized patient evaluation on eye dryness (SPEED) and dry eye-related quality of life score (DEQS) scores (r=0.59, 0.43), respectively. TFI enabled to quantify the LLT and MALT separately over time and shows the moderate correlations between TFI measurements and clinical parameters, which yields the potential for TFI to serve as a complementary tool for assessing dry eye and MGD.

PurposeTo develop and validate a novel method for quantifying blood flow velocity in ocular vessels using speckle pattern analysis in optical coherence tomography (OCT) images.MethodsWe developed an OCT-based methodology that quantifies flow velocity by analyzing speckle structures within OCT images to derive a relative flow value (RFV) based on the horizontal derivative of speckle patterns. A model eye with 150-µm capillary tubing was used to evaluate speckle pattern analysis at controlled flow rates of human and porcine blood. We assessed the correlation between RFV and actual flow velocities and examined measurement consistency across vessel sectioning angles varying ±20° from perpendicular.ResultsRFV exhibited a power-law relationship with actual flow velocities, RFV = 169.6 × (Actual Flow)0.264 (r2 = 0.983), and maintained accuracy without saturation up to 70 mm/s. Measurements remained consistent across vessel sectioning angles. Intraluminal speckle structures changed dynamically with flow velocity, and averaged images revealed characteristic hourglass profiles at higher velocities. In a patient with central retinal vein occlusion, RFV detected altered pulsatility and reduced venous flow, aligning with clinical expectations.ConclusionsThis speckle-based OCT method provides a non-invasive, depth-resolved approach for quantifying ocular blood velocity with minimal computational requirements. It holds potential for diagnosing and monitoring vascular abnormalities in ocular and systemic diseases. Further validation is necessary across diverse patient populations.Translational RelevanceThis method simplifies blood flow quantification, enhancing the role of OCT in hemodynamic assessment both ocularly and systemically.

PurposeThe purpose of this study was to investigate the relationship among deep optic nerve head (ONH), lamina cribrosa (LC), and peripapillary sclera (pSc) configurations in healthy eyes.MethodsThis prospective cross-sectional study included 205 healthy eyes of 141 subjects. Multivariable linear mixed models identified factors associated with LC curvature index, prelaminar thickness (PLT), pSc angle, and LC depth (LCD). Explanatory variables included age, gender, intraocular pressure, axial length (AXL), visual field sensitivity, disc area, disc ovality, disc torsion, Bruch's membrane opening (BMO)-minimum rim width (MRW), BMO and anterior scleral canal opening (ASCO) area, peripapillary zone area with and without Bruch's membrane (PPZ+BM/–BM), and peripapillary choroidal thickness (pChT). A sub-analysis was conducted by dividing the eyes at the median AXL.ResultsLC curvature was flatter in eyes with large PPZ-BM, long AXL, and shallow LCD (P = 0.002, P = 0.015, and P = 0.042, respectively). Similar factors exhibited consistent effects in longer AXL eyes, whereas different factors, BMO-MRW, ASCO-area, and pSc-angle, were associated in shorter AXL eyes (P = 0.006, P = 0.012, and P = 0.018. respectively). PLT was thinner in eyes with thin BMO-MRW, large ASCO area, and young age (P < 0.001, P < 0.001, and P = 0.009, respectively). The pSc angle was steeper in eyes with long AXL and large PPZ+BM (P < 0.001). LCD was deeper in eyes with thick pChT, thin BMO-MRW, and small ASCO area (P < 0.001, P < 0.001, and P = 0.004, respectively).ConclusionsNovel associations between LC configurations with scleral canal size, PPZ+BM/–BM, and BMO-MRW were found after correction for confounding deep ONH morphologies. Given that these structures are associated with glaucomatous changes, these inter-structure correlations should be considered when distinguishing LC changes between healthy and glaucomatous eyes.

We propose a model eye for OCT angiography (OCT-A) with a retinal phantom without using any liquid flow. Instead of the flow, this phantom actively uses the particle movement caused by Brownian motion. The magnitude of the particle movement depends on particle size and liquid viscosity. We used much smaller particles of 150 to 250nm than erythrocytes so that Brownian motion generates sufficient particle displacement in OCT-A interscan duration. We controlled the liquid viscosity by changing the mixture ratio. The liquids were sealed in the phantom channels which having 100μm in height and 40 or 60μm in width. The OCT-A signals were successfully obtained at the particle-distributed liquids in the phantom channels. The obtained OCT-A signals became larger at lower viscosity liquid and were comparable to those at the human-eye fundus vessels. The proposed technique using Brownian motion in sealed liquid is promising to constitute the model eye that widely operatable in imaging validation without flow control and system maintenance.

Abstract As previously reported, we have proposed a vertical distribution of seismic design load for seismically isolated buildings (SIBs) corresponding to diversity of seismic isolation devices such as hysteretic dampers and velocity‐dependent dampers. This proposed seismic design load is obtained from the relationship between response amplification caused by higher mode responses and the isolation ratio which represents structural characteristics of SIBs. In this paper, we build a concept of the equivalent isolation ratio which has applicability to various dampers in order to simplify an evaluation formula of vertical distribution of seismic design load. Moreover, an effect of the combined application of various dampers on vertical distribution of shear force coefficient of SIBs is analyzed on the basis of the equivalent isolation ratio.

In our previous study, we visualized and systematically evaluated gas leakage from the forceps plug of the gastrointestinal endoscope system using the Schlieren system. In order to minimize the potential risk of infection from gas leakage from the gastrointestinal endoscope, the development of a new forceps plug was considered urgent. In this study, we analyzed the structure of commercially available forceps plugs and attempted to develop new forceps plugs with improvements. Microfocus computed tomography was used to nondestructively analyze the structural changes that occur when forceps are inserted into a commercially available forceps plug. Based on the findings, the basic structure of the newly developed forceps plug was set. We examined the airtightness of these newly developed plugs using the Schlieren system and also compared their fractional resistance with those of commercially available plugs. As a result of the nondestructive analysis, all of the commercially available plugs had a single valve, and the cleavage created in the valve during forceps, insertion was large in the case of plugs with slit-type entrances. In the newly developed forceps plugs, all four types of plugs showed less gas leakage and similar or better usability compared to the commercially available plugs. The structural weaknesses of the existing gastrointestinal endoscopic forceps plugs were identified. Based on the findings, we froze the design of a prototype of a new forceps plug that was airtight and not inferior in usability compared to commercially available plugs.