Detachment Volume Research Articles

Artificial intelligence-based analysis of retinal fluid volume dynamics in neovascular age-related macular degeneration and association with vision and atrophy.

To characterise morphological changes in neovascular age-related macular degeneration (nAMD) during anti-angiogenic therapy and explore relationships with best-corrected visual acuity (BCVA) and development of macular atrophy (MA). Post-hoc analysis of the phase III HARBOR trial. SD-OCT scans from 1097 treatment-naïve nAMD eyes were analysed. Volumes of intraretinal cystoid fluid (ICF), subretinal hyperreflective material (SHRM), subretinal fluid (SRF), pigment epithelial detachment (PED) and cyst-free retinal volume (CFRV) were measured by deep-learning model. Volumes were analysed by treatment regimen, macular neovascularisation (MNV) subtypes and topographic location. Associations of volumetric features with BCVA and MA development were quantified at month 12/24. Differences in feature volume changes by treatment regimens and MNV subtypes were observed. Each additional 100 nanolitre unit (AHNU) of residual ICF, SHRM and CFRV at month 1 in the fovea was associated with deficits of 10.3, 7.3 and 12.2 letters at month 12. Baseline AHNUs of ICF, CFRV and PED were associated with increased odds of MA development at month 12 by 10%, 4% and 3%. While that of SRF was associated with a decrease in odds of 5%. Associations at month 24 were similar to those at month 12. Eyes with different MNV subtypes showed distinct trajectories of feature volume response to treatment. Higher baseline volumes of ICF or PED and lower baseline volume of SRF were associated with higher likelihoods of MA development over 24 months. Residual intraretinal fluid, including ICF and CFRV, along with SHRM were predictors of poor visual outcomes.

The interaction between water droplets and superhydrophobic holes: Detachment and penetration

Water droplets of varying volumes exhibit distinct behaviors at the tip of a needle under the influence of gravitational force: larger droplets fall from the needle tip, while smaller droplets adhere to the needle tip. By integrating a superhydrophobic hole, which allows the needle to pass through but hinders droplets' passage, a method to allow smaller droplets to fall from the needle was evaluated. The interaction between water droplets and a superhydrophobic hole was studied experimentally, and two phenomena were observed: either the droplet detached from the needle tip or the needle pulled it through the superhydrophobic hole. A critical detachment volume Vcrid0,D, dependent on the needle diameter d0 and the superhydrophobic hole diameter D, determines droplet behavior. When the volume of the droplet Vdroplet>Vcrid0,D, the droplet detaches from the needle tip. When the Vdroplet<Vcrid0,D, the droplet penetrates through the superhydrophobic hole. The results show that the critical detachment volume Vcrid0,D increases with an increase in d0 for a given superhydrophobic hole and with an increase in D for a given needle. To enable a 0.25 μl droplet to fall from a 32G needle, a superhydrophobic hole of 0.48 mm diameter was employed. Furthermore, a mechanical model based on force equilibrium was developed to describe the interaction between water droplets and a superhydrophobic hole.

Investigation of the 2010 rock avalanche onto the regenerated glacier Brenndalsbreen, Norway

Rock avalanches onto glaciers are rare in Norway. Here, we examine a rock avalanche that spread onto the regenerated Brenndalsbreen, an outlet glacier from Jostedalsbreen ice cap. The rock avalanche is intriguing in that limited information exists with respect to the exact time of failure, location of detachment area, and preparatory and triggering processes. Based on an analysis of ice stratigraphy and photographic documentation, we assess that the event happened between mid-March and June 4, 2010. A potential triggering factor could have been heavy snow and rainfall combined with above freezing air temperatures on March 18–19, 2010. We use digital terrain models to determine that the detachment area is at an almost vertical rock slope in a narrow gorge above Lower Brenndalsbreen. The deposit volume is estimated to 0.130 ± 0.065 Mm3, and the H/L ratio and fahrböschung are 0.45 and 24°, respectively. We apply a Voellmy flow model to confirm the detachment location and volume estimate by producing realistic runout lengths. Although glacial debuttressing may have been a likely preparatory process, the detachment area was exposed for 45–70 years before the rock avalanche occurred. The supraglacial rock avalanche debris was separated into two branches with a distinct melt-out line across the glacier. The debris reached the glacier front in 2019 and 2020, where it started being deposited proglacially while Lower Brenndalsbreen kept receding. The 2010 Brenndalsbreen rock avalanche may not be a unique event, as deposits constituting evidence of an old rock avalanche are currently melting out at the glacier front.

3D Mapping of the DMEK Detachment Area from OCT Scans of the Anterior Segment of the Eye - Clinical Applications.

Graft detachment is the most common complication after Descemet membrane endothelial keratoplasty (DMEK). To assess the amount of graft detachment, precision is limited when using slit-lamp biomicroscopy. Detachment of DMEK grafts can be assessed automatically on anterior segment optical coherence tomography (AS OCT) images and allows visualization of the area and volume of detachment using 3D maps. This article provides an overview of its applications such as accurately assessing the course of natural graft attachment, identification of potential risk factors for detachment and evaluation of the long-term effect of graft detachment. The 3D map of DMEK detachment may support researchers and clinicians in precise quantification of the area and volume of graft detachment even in large data sets, and the intuitive, fast and reliable evaluation.

Visual Outcome and Fluid Changes Between Eyes With Polypoidal Choroidal Vasculopathy Receiving Biosimilar CKD-701 or Reference Ranibizumab Therapy: A Post Hoc Analysis of a Phase 3 Randomized Clinical Trial

Purpose To compare the visual outcome and fluid features of a proposed biosimilar, CKD-701, versus the reference ranibizumab in eyes with polypoidal choroidal vasculopathy (PCV). Methods This was a post hoc analysis of a phase 3 randomized clinical trial assessing the efficacy and safety of CKD-701 and ranibizumab. A total of 73 PCV eyes were assigned randomly to either CKD-701 (36 eyes) or ranibizumab (37 eyes). The mean changes in best-corrected visual acuity (BCVA), central retinal thickness (CRT), pigment epithelial detachment (PED) volume, and fluid features were compared. Results After three loading injections, the mean change in BCVA (letters) was +7.50 in the CKD-701 group and +6.32 in the ranibizumab group (p = .447). The changes in CRT and PED volume of the CKD-701 group (−107.25 ± 102.66 μm and −0.22 ± 0.46 mm3) were similar to those of the ranibizumab group (−96.78 ± 105.00 μm and −0.23 ± 0.54 mm3) (p = .668 and p = .943, respectively). Proportions of eyes with subretinal, intraretinal and sub-retinal pigment epithelium (RPE) fluids after three loading injections were not different between CKD-701 group (33.3%, 13.9% and 42.9%) and ranibizumab group (51.4%, 16.2% and 40.0%) (p = .071, p = 1.000 and p = .808). The visual and anatomical changes were similar between two groups at month 6 and 12 (all, p > .05). Conclusion Biosimilar CKD-701 monotherapy resulted in comparable visual and anatomical changes to those achieved with reference ranibizumab in PCV eyes.

Short-term response to anti-VEGF as indicator of visual prognosis in refractory age-related macular degeneration.

Some patients with neovascular age-related macular degeneration (nAMD) respond insufficiently to anti-VEGF treatment despite maximal monthly intravitreal injections. Their short-term response between injections was investigated for extent and visual prognosis. Monocentric retrospective observational study. 45 eyes from 41 patients with refractory nAMD (who previously received at least 12 months of anti-VEGF treatment), evaluated by optical coherence tomography (OCT) in between monthly anti-VEGF injections. The fluid profile on OCT was evaluated before, 1 week after, and 1 month after an intravitreal injection, using central retinal thickness (CRT), manual measurements, and fluid specific volumetric measurements performed by an automated algorithm based on artificial intelligence. A significant improvement was found at week 1 in terms of CRT (p < 0.0001), intraretinal (IRF) (p = 0.007), subretinal fluid (SRF) (p < 0.0001), and pigment epithelium detachment (PED) volume (p < 0.0001). Volumetric fluid measures revealed a >50% reduction at week 1 for both IRF and SRF for approximately two-thirds of eyes. Poorer short-term response was associated with larger exudative fluid amounts (IRF + SRF) (p = 0.003), larger PED (p = 0.007), lower visual acuity (p = 0.004) and less anatomic changes at treatment initiation (p < 0.0001). Univariate and multivariate analysis revealed that visual outcomes 4 and 5 years later was significantly worse with weaker short-term responsiveness (p = 0.005), with the presence of atrophy (p = 0.01) and larger PED volumes (p = 0.002). Incomplete responders to anti-VEGF showed a significant short-term response, identifiable at 1 week after injection, with rapid recurrence at 1 month. Weaker short-term responsiveness at 1 week was associated with poorer long term visual prognosis. These patients may need adjuvant treatment to improve their prognosis.

Supine Positioning for Graft Attachment After Descemet Membrane Endothelial Keratoplasty: A Randomized Controlled Trial

The Supine Positioning for Descemet Membrane Endothelial Keratoplasty Attachment (SUPER-DMEK) trial assessed the efficacy of prolonged supine head positioning on graft attachment. Randomized controlled trial. Participants with Fuchs' dystrophy were randomized to 5 days of supine head positioning (intervention) or to 1 day (control). Participants, surgeons, and investigators were masked until the day after surgery. Adherence to the allocated intervention was monitored using a head sensor. Main outcome measures were area and volume of graft detachment (coprimary end points) 2 weeks after surgery quantified using a validated neural network for image segmentation on anterior segment optical coherence tomography images, and repeat air injection (rebubbling), subjective visual function, and adverse events (secondary end points). A total of 86 participants received the allocated intervention (35 eyes intervention and 51 eyes control). In the intention-to-treat analysis, the mean area of graft detachment was 28.6% in the intervention arm and 27.5% in the control arm (adjusted between-arm difference, 1.3; 95% CI, -8.7 to 11.4; P = .80). Results for volume of detachment and as-treated analyses based on head position sensor data indicated no potentially clinically relevant effect of prolonged supine positioning on graft attachment. Results were not compatible with a relevant treatment effect on rebubbling or subjective visual function. Adverse events, most commonly back pain, were more common and more severe with the intervention. In this randomized controlled trial, graft attachment was not improved with prolonged supine head positioning. Prolonged supine positioning frequently caused back pain. Prolonged supine positioning after Descemet membrane endothelial keratoplasty for Fuchs' dystrophy may not be needed in routine practice.

Influence of the wettability dividing line on bubble growth and detachment behavior in a von Kármán swirling flow field

The contact-angle (CA) hysteresis generated by the difference between the advancing and receding CAs of a droplet on an inclined surface generates an adhesion force that can hold the droplet on the surface. Similarly, the CA hysteresis generated by a wettability dividing line (WDL) between the superhydrophobic and superhydrophilic regions can improve the anti-shear stability of bubbles in water, with a maximum range of more than 150° for the difference between the advancing and receding CAs. Based on this mechanism, the influence of a WDL on the growth and detachment behavior of bubbles at different Reynolds numbers (Re) in a von Kármán swirling flow field was experimentally studied. The results show that the WDL significantly improves the anti-shear stability of bubbles when compared to uniform superhydrophobic and hydrophilic surfaces. Furthermore, the detachment volume and maximum contact width decrease with increasing Re, while the tilt angle and asymmetry ratio increase significantly. The fluctuation amplitudes of these parameters gradually increase with rising Re. Based on variations in these parameters, bubbles' growth behavior can be classified into three modes: stabilization, transition, and oscillation. Additionally, the constraint mechanism of a WDL on a bubble was analyzed based on variations in the CA hysteresis generated by the WDL and the maximum contact width. Finally, the detachment dynamics of bubbles in the three modes were analyzed based on a force–balance model.

Optical coherence tomography angiography biomarkers in a bi-monthly maintenance dosing aflibercept in patients with neovascular age-related macular degeneration

PurposeTo evaluate the correlations between swept-source optical coherence tomography angiography (SS-OCTA) parameters and clinical outcomes in eyes with neovascular age-related macular degeneration (nAMD) administered a bimonthly intravitreal aflibercept regimen.MethodsThis prospective, single-arm, interventional study enrolled 33 patients with treatment-naïve nAMD. The eyes received three monthly aflibercept injections followed by five bi-monthly regimens (total 50 weeks). The structural parameters including central subfield thickness (CST) and 5 mm pigment epithelial detachment (PED) volume and microvascular parameters including macular neovascularization (MNV) area, vessel density (VD), and vessel length density (VLD) were recorded every before and 1 week after treatment.ResultsPatients who gained > 5 letters of best-corrected visual acuity (BCVA) from the baseline showed greater decreases in VD and VLD during the loading phase. Patients without recurrent or persistent fluid during the maintenance phase showed greater decreases in CST and 5 mm PED volume after the first injection. The decrease in mean VD during the loading phase was significantly correlated with the final BCVA (r = -0.820, p = 0.004). Moreover, the decrease in mean VLD during the loading phase was significantly correlated with the improvement in the final BCVA (r = -0.726, p = 0.017).ConclusionsThe decrease in mean VD during the loading phase was significantly negatively correlated with the final BCVA at the last visit. The decrease in mean VLD during the loading phase, mean CST during the loading phase, and the improvement in final BCVA showed significant correlations. Therefore, early changes in OCTA microvascular and OCT structural parameters could help predict clinical outcomes in nAMD.Trial RegistrationThe trial was registered with the Clinical Research Information Service (CRIS), which joined the WHO International Clinical Trials Registry Platform (ICTRP) (Registration number: KCT0007375, Date of first trial registration: 10/06/2022).

Comparison of Optical Coherence Tomography Biomarkers between Bevacizumab Good Responders and Nonresponders Who were Switched to Dexamethasone Implant in Diabetic Macular Edema.

To compare volumetric optical coherence tomography (OCT) biomarkers in bevacizumab responsive and bevacizumab refractory diabetic macular edema (DME) patients switched to the dexamethasone implant to ultimately identify possible prognostic indicators. Retrospective analysis of DME patients treated with bevacizumab were done. Patients were divided into those who showed response to bevacizumab (bevacizumab only group) and others who were switched to the dexamethasone implant due to lack of response to bevacizumab (switching group). Volumetric OCT biomarkers such as central macular thickness (CMT), inner and outer cystoid macular edema (CME) volume, serous retinal detachment (SRD) volume, retinal volume (CME + SRD volume) within the 6-mm Early Treatment of Diabetic Retinopathy Study circle were calculated. OCT biomarkers were followed up throughout treatment. Among total of 144 eyes, 113 patients were included in the bevacizumab only group and 31 patients were included in the switching group. Compared to the bevacizumab only group, the switching group showed higher baseline CMT (558.00 ± 209.60 µm vs. 454.96 ± 125.88 µm, p = 0.003), larger inner CME (6.02 ± 1.43 mm3 vs. 5.12 ± 0.87 mm3, p = 0.004) and SRD volume (0.32 ± 0.40 mm3 vs. 0.11 ± 0.09 mm3, p = 0.015) and higher proportion of patients with SRD (58.06% vs. 31.86%, p = 0.008). In the switching group, CMT, inner CME and SRD volume all showed significant reduction after switching to the dexamethasone implant. DME with large SRD and inner nuclear layer edema volume may be more effectively treated with the dexamethasone implant than bevacizumab.

Bubble migration characteristics in power transformer oil under coupled stresses of forced vibration and electrical field

AbstractThe stresses existing in power transformers lead to the generation of bubbles. They are the primary source that worsens and leads to insulation failure. Due to the complexity of bubble dynamics, it is challenging to figure out bubble mechanisms. However, creation, migration, and accumulation mechanisms require further explanation. A set of experiments has been conducted to provide a scientific overview of bubbles. The results revealed that buoyancy is dominant in low electric fields, while high electric fields affect bubbles' rise. Bubbles stretch and oscillate while moving. When the electric field is not strong, the AC field reduces the duration and volume of bubble detachment. Vibration stress on the other side is leading the bubble motion including detachment frequency and migration speed. Under the combination of AC and vibration stresses, the bubble distortion degree aggravates and bubble gathering formation is easy. This research can provide a deeper acumen of the bubble's actions beneath a power transformer under a combination of vibration and electric fields. It provides essential technique parameters to deal with while investigating bubble's problems and related engineering research areas.

Graft Detachment after Descemet Membrane Endothelial Keratoplasty with and without Cataract Surgery.

To evaluate graft detachment after Descemet membrane endothelial keratoplasty (DMEK) in pseudophakic eyes and DMEK combined with cataract surgery (triple DMEK). Analysis of 3 single-center prospective cohort studies and 1 randomized controlled trial. Participants with Fuchs' endothelial corneal dystrophy. A validated neural network for image segmentation quantified graft detachment on anterior segment OCT (AS-OCT) images 3 days after DMEK and at the 2-week postoperative visit. Area and volume of graft detachment were compared between DMEK only and triple DMEK using generalized estimating equation models and adjusting for participant age and the size of the air bubble. Area and volume of DMEK graft detachment. Among 207 participants with 270 eyes included, 75 pseudophakic eyes had DMEK only and 195 eyes had triple DMEK. A total of 147 eyes had less than one third of detachment at day 3. In 139 of these eyes (95%), detachment was still less than one third at the 2-week scan, indicating that postoperative graft detachment at 2 weeks occurred mainly in eyes with early detachment. When superimposing all 3-dimensional maps from 2 weeks after surgery, the central graft was mainly attached and detachment was located at the graft margin. The mean area of graft detachment decreased from 28% in DMEK only and 38% in triple DMEK to 16% in DMEK only and 25% in triple DMEK at the 2-week postoperative visit. At 2 weeks, the mean area of detachment was 1.85-fold higher (95% confidence interval [CI], 1.34-2.56) and the mean volume was 2.41-fold higher (95% CI, 1.51-3.86) in triple DMEK compared with DMEK. A total of 46 eyes received rebubbling procedures, with 7 eyes (9%) in the DMEK group and 39 eyes (20%) in the triple DMEK group (adjusted risk ratio, 3.1; 95% CI, 1.3-7.1), indicating that rebubbling was more common in eyes undergoing triple DMEK. Automated segmentation of AS-OCT images allowed precise quantification of graft detachment over time and identified DMEK combined with cataract surgery as a risk factor. Frequency of operative follow-up might be guided by extent of detachment in the first postoperative days after DMEK.

Challenges Assessing Rock Slope Stability Using the Strength Reduction Method with the Hoek–Brown Criterion on the Example of Vals (Tyrol/Austria)

To estimate the hazard posed by rock slopes, it is essential to determine the overall stability and potential detachment volume. This is mostly solved using numerical methods together with the strength reduction method (SRM). Many calculation programs do not provide a direct implementation of the Hoek–Brown (HB) criterion. Equivalent Mohr–Coulomb (MC) parameters are often used. Especially for steep rock slopes, the use of equivalent MC parameters with numerical codes and the SRM lead to poor estimates of safety factors. The problem lies in the required and often difficult estimation of a suitable range of minor principal stresses over a ‘slope height’. In the example of the stability analysis of the rock slope Vals in Tyrol/Austria, we show the differences between the application of equivalent MC parameters and a direct application of the HB criterion with apparent MC parameters. The detachment volume and stability are overestimated when applying equivalent MC parameters, as confirmed by calculations with the continuum mechanics code FLAC3D (Itasca Consulting Group). However, the SRM with HB material (i.e., apparent MC parameters) results in a safety factor that cannot be applied to HB parameters. To date, it has not been possible to determine the HB parameters for limit equilibrium via the SRM. This challenge was overcome by fitting an HB envelope to the original HB shear envelope reduced by the safety factor. The envelope is adjusted by two HB variables: GSI and D. This allows to determine the HB parameters at limit equilibrium. It helps to make more realistic predictions about the detachment mechanism and volume.

Оптическая когерентная томография-ангиография в диагностике начальных проявлений неоваскулярного процесса при центральной серозной хориоретинопатии

In the chronic form of central serous chorioretinopathy (CSC), such a complication as the development of a neovascular membrane occurs, which requires a fundamentally different therapeutic approach. In this case, the correct diagnosis is very important. Purpose. To determine the value of the method of optical coherence tomography with angiography mode (OCTA) in the detection of neovascular process in CSC. Material and methods. The data of 29 patients (34 eyes) with acute (16 eyes) and chronic (18 eyes) forms of CSC were analyzed; we assessed best corrected visual acuity (BCVA), perimetry – the presence of scotoma, the presence of exudative detachment of neuroepithelium and retinal pigment epithelium (RPE) the presence or absence of newly formed vessels in the area of RPE detachment, the thickness and total volume of the retina in the macula. Results. According to the results of examinations, BCVA averaged 0.7 ± 0.1, relative scotomas were detected in 10 cases, retinal thickness averaged 306±18 µm, retinal volume 7.18 ± 0.5 mm3. In the chronic form of CSC, neovascularization under RPE was detected in 4 cases, which amounted to 22.2 %. Conclusion. OCT angiography makes it possible to detect the neovascular membrane, which determines the choice of treatment for CSC. Keywords: central serous chorioretinopathy, neovascular membrane, OCT angiography.

Three-Dimensional Map of Descemet Membrane Endothelial Keratoplasty Detachment: Development and Application of a Deep Learning Model.

PurposeTo develop and apply a neural network for quantification of endothelial corneal graft detachment using anterior segment (AS) OCT.DesignTraining and validation of a neural network and application within a prospective cohort.ParticipantsPatients two weeks after Descemet membrane endothelial keratoplasty.MethodsInvestigators manually labeled the posterior cornea and the graft in cross-sectional images of rotational AS OCT scans. Neural networks for image segmentation were trained to identify the area of graft detachment on cross-sectional images. The best-performing neural network with the lowest misclassification (Youden index) and highest spatial overlap with the ground truth (Dice coefficient) was selected and evaluated in a separate dataset. Three-dimensional maps of the area and volume of graft detachment were calculated. For application, the neural network’s rating on the detachment was compared with slit-lamp–based ratings of cornea specialists on the same day as the AS OCT imaging took place.Main Outcome MeasuresYouden index and Dice coefficient.ResultsNeural networks were trained on 27 AS OCT scans with 6912 labeled images. Among 48 combinations of probability thresholds and epoch states, the best-performing neural network showed a Youden index of 0.99 and a Dice coefficient of 0.77, indicating low misclassification and good spatial overlap on individual image segmentation. In the validation set unknown to the neural network with 20 scans (5120 images), the Youden index was 0.85 and the Dice coefficient was 0.73, and a high overall performance compared with the manually labeled ground truth (R2 = 0.90). In the application set with 107 eyes, the neural network estimated the mean percent detachment larger than the cornea specialist (mean difference, 8.2 percentage points; 95% confidence interval, 6.2–10.2). Masked review of 42 AS OCTs with more than ±10 percentage points difference in ratings showed that clinicians underestimated the true detachment in cases with significant detachment requiring intervention.ConclusionsDeep learning-based segmentation of AS OCT images quantified the percent and the volume of DMEK graft detachment with high precision. Fully automated 3-dimensional quantification of graft detachment is highly sensitive, particularly in corneas with a significant amount of detachment, and may support decision making.

Swept-Source OCT Angiographic Characteristics of Treatment-Naïve Nonexudative Macular Neovascularization in AMD Prior to Exudation.

PurposeTo investigate the characteristics of treatment-naïve nonexudative macular neovascularization (MNV) in age-related macular degeneration before the onset of exudation using swept-source optical coherence tomography angiography.MethodsMNV area, choriocapillaris (CC) flow deficits (FDs), vessel area density (VAD), vessel skeleton density (VSD), retinal pigment epithelial detachment (PED) volume, mean choroidal thickness (MCT), and choroid vascularity index (CVI) measurements were assessed at two visits prior to exudation. We compared measurements made at the second visit and the rate of change between visits in eyes with and without exudation. The differences in these parameters between eyes with and without subsequent exudation were summarized with 95% confidence intervals (CIs).ResultsTwenty-one eyes with nonexudative MNV were identified and followed. Nine eyes developed exudation, and 12 eyes did not develop exudation. Differences between these groups of eyes for all parameters tended to be small, and the 95% CIs largely ruled out any substantial differences. Overall, eyes with exudation had 24% smaller VAD, 20% smaller VSD, and 33% smaller PED volume measurements. No noteworthy differences were observed for MNV area, CC FDs, MCT, or CVI measurements.ConclusionsThe onset of exudation was correlated with lesions having less vascularity and smaller PED volume measurements, but measurements of MNV area, CC FDs, MCT, and CVI were not correlated with near-term exudation. Investigations are ongoing to further explore these and other anatomic changes as harbingers of near-term exudation.

One-year results of intravitreal conbercept in treatment-naïve subjects with polypoidal choroidal vasculopathy.

To evaluate the functional and structural outcomes of intravitreal conbercept monotherapy using a "3 + pro re nata (PRN)" regimen in treatment-naïve subjects with polypoidal choroidal vasculopathy (PCV) up to 12months. Thirty subjects (30 eyes) with PCV participated in this interventional, retrospective study. All subjects received intravitreal injections of 0.5mg (0.05ml) conbercept using a "3 + PRN" regimen for 12months. The changes in best-corrected visual acuity (BCVA) and optical coherence tomography (OCT) parameters, polyp lesion area, and regression rate were evaluated at baseline, month 3, and month 12. At the study end-point, BCVA improved significantly from 52.80 ± 17.17 ETDRS letters at baseline to 62.20 ± 18.96 letters (P< 0.001), with a mean gain of 9.40 ± 14.97 letters. The central retinal thickness (CRT) significantly reduced from 454.93 ± 147.31μm at baseline to 308.73 ± 106.80μm (P< 0.001) at end-point, and the total macular volume (TMV) decreased from 9.51 ± 1.04mm3 at baseline to 8.32 ± 0.84mm3 at end-point (P< 0.001). The mean volume of pigment epithelial detachment (PED) decreased from 0.73 ± 0.97mm3 at baseline to 0.48 ± 0.71mm3 (P<0.05) at month 3. At month 12, the mean volume of PED was 0.57 ± 0.80mm3 (P> 0.05 compared to baseline). After the 3-monthly loading injections, 6 eyes (20.0%) showed complete polyp regression, whereas a total of 19 eyes (63.5%) showed complete regression at month 12. The average injections given per subject were 7.70 ± 1.81. Intravitreal conbercept using the "3 + PRN" regimen was effective in the treatment of PCV.

On the validity of force balance models for predicting gravity-induced detachment of pendant drops and bubbles

We show that it is fundamentally inaccurate to apply force-balance models to predict the gravity/buoyancy induced detachment of quasi-steadily growing pendant droplets/bubbles. We solve the governing Young–Laplace (Y–L) equation to clarify that all forces acting on a droplet/bubble always sum up to zero, even prior to or beyond the well-accepted critical volume of detachment. Accordingly, the typical force balance models reported in the literature do not hold any physical justification and are merely a curve fit to the experimental trends. We clarify that the physical constraints imposed by the contact line conditions and the surface geometry are instead responsible for detachment.

Bubble Formation in Yield-Stress Fluids Using a Coupled Level-Set and Volume-of-Fluid Method.

The bubble formation under the influence of orifice diameter submerged in yield-stress fluids was studied numerically using a coupled level-set (LS) and the volume-of-fluid (VOF) method and was in contrast with that seen in Newtonian fluids. The bubble formation process had a good consistency by virtue of comparing numerical simulation and experiment. The process of bubble formation could be divided into two parts, bubble expansion stage and stretch stage. The influence of orifice diameter and liquid rheological characteristics (consistency coefficient, flow index, and yield stress) on the bubble formation parameters (the bubble formation time, detachment volume, and aspect ratio) was investigated. The results revealed that the bubble detachment volume increases with the increase of orifice diameter, consistency coefficient, flow index, and yield stress. In different kinds of fluids, the formation time and detachment volume of bubbles in the shear-thinning fluid were the lowest, followed by the Newtonian fluid, and finally, in yield-stress fluids.

A comparative study of bubble formation characteristics in non-Newtonian and high-viscosity Newtonian fluids by a laser image technique

A laser image measurement system has been established to study the problem of dynamic bubble formation from a submerged orifice in two kinds of high-viscous fluids, namely Newtonian glycerol aqueous solution and non-Newtonian carboxymethylcellulose (CMC) aqueous solutions. The bubble generation process was measured accurately by means of He-Ne laser as light source using the beam expanding and light amplification technology. The whole formation process, including bubble expansion, stretching and detachment three stages, and the dynamic characteristics of each stage, were investigated experimentally by analyzing comparatively the evolution of the instantaneous shape, volume, surface area, and deformation rate in both fluids. The influences of solution mass concentration, gas chamber volume and orifice diameter on bubble detached volume were discussed respectively, and the results reveals that bubble begins to grow spherically due to the predominant role of surface tension, and then is elongated gradually owing to the increasing buoyancy force. Compared with Newtonian fluid, bubble formed in non-Newtonian fluid presents a slim shape as a result of the shear-thinning effect of CMC solution. Bubble detachment volume in both kinds of fluids increases with solution mass concentration and gas chamber volume, but declines with orifice inner diameter, respectively.