Peripheral Distortion Research Articles

In silico validation of non-invasive arterial compliance estimation and potential determinants of its variability.

Arterial compliance (AC) is an important cardiovascular parameter characterizing mechanical properties of arteries. AC is significantly influenced by arterial wall structure and vasomotion, and it markedly influences cardiac load. A new method, based on a two-element Windkessel model, has been recently proposed for estimating AC as the ratio of the time constant T of the diastolic blood pressure decay and peripheral vascular resistance derived from clinically available stroke volume measurements and selected peripheral blood pressure parameters which are less prone to peripheral distortions. The aim of this study was to validate AC estimation using a virtual population generated by in silico model of the systemic arterial tree. In the second part of study, we analysed causal coupling between AC oscillations and variability of its potential determinants - systolic blood pressure and heart rate in healthy young human subjects. The pool of virtual subjects (n=3818) represented an extensive AC distribution. AC was estimated from the peripheral blood pressure curve and by the standard method from the aortic blood pressure curve. The proposed method slightly overestimated AC set in the model but both ACs were strongly correlated (r=0.94, p<0.001). In real data, we observed that AC dynamics was coupled with basic cardiovascular parameters variability independently of the autonomic nervous system state. In silico analysis suggests that AC can be reliably estimated by noninvasive method. The analysis of short-term AC variability together with its determinants could improve our understanding of factors involved in AC dynamics potentially improving assessment of AC changes associated with atherosclerosis process. Key words Arterial compliance, Cardiovascular model, Arterial blood pressure, Causal analysis, Volume-clamp photoplethysmography.

Modern Approach to Diabetic Retinopathy Diagnostics.

This article reviews innovative diagnostic approaches for diabetic retinopathy as the prevalence of diabetes mellitus and its complications continue to escalate. Novel techniques focus on early disease detection. Technological innovations, such as teleophthalmology, smartphone-based photography, artificial intelligence with deep learning, or widefield photography, can enhance diagnostic accuracy and accelerate the treatment. The review highlights teleophthalmology and handheld photography as promising solutions for remote eye care. These methods revolutionize diabetic retinopathy screening, offering cost-effective and accessible solutions. However, the use of these techniques may be limited by insurance coverage in certain world regions. Ultra-widefield photography offers a comprehensive view of up to 80.0% of the retina in a single image, compared to the 34.0% coverage of the traditional seven-field imaging protocol. It allows retinal imaging without pupil dilation, especially for individuals with compromised mydriasis. However, they also have drawbacks, including high costs, artifacts from eyelashes, eyelid margins, and peripheral distortion. Recent advances in artificial intelligence and machine learning, particularly through convolutional neural networks, are revolutionizing diabetic retinopathy diagnostics, enhancing screening efficiency and accuracy. FDA-approved Artificial Intelligence-powered devices such as LumineticsCore™, EyeArt, and AEYE Diagnostic Screening demonstrate high sensitivity and specificity in diabetic retinopathy detection. While Artificial Intelligence offers the potential to improve patient outcomes and reduce treatment costs, challenges such as dataset biases, high initial costs, and cybersecurity risks must be considered to ensure safety and efficiency. Nanotechnology advancements further enhance diagnosis, offering highly branched polyethyleneimine particles with fluorescein sodium (PEI-NHAc-FS) for better fluorescein angiography or vanadium oxide-based metabolic fingerprinting for early detection.

Comparison of Foldscope to optical microscope to identify basic histology

Introduction: The teaching of basic histology is crucial in the training of healthcare professionals. Traditionally, the optical microscope is used, but it has limitations such as cost and the need for specific infrastructure. The Foldscope (FS), a low-cost and easy-to-handle tool, emerges as a promising alternative. Objective: To validate the efficacy of the FS in teaching basic histology for healthcare training, comparing it with the traditional method of binocular optical microscopy. Method: We used a kit of prepared histology slides, first examined with an optical microscope and then with the FS. We used a smartphone for image capture, ensuring comparative accuracy between the methods. Results: The FS could observe structures seen with a 10x objective in conventional microscopy but with less sharpness and some peripheral distortions. The applicability of the FS proved effective in observing structures of various tissues, such as the thyroid, arteries, veins, and neurons, although it has limitations for teaching muscular and testicular tissues. Conclusion: The FS is an innovative educational tool that bridges the gap between theory and practice in histology teaching. It is a complementary resource to the optical microscope, effectively identifying structures with about 100x magnification. However, it does not completely replace the optical microscope due to its limitations in magnification and image quality.

Active Object Detection and Tracking Using Gimbal Mechanisms for Autonomous Drone Applications

Object recognition, localization, and tracking play a role of primordial importance in computer vision applications. However, it is still an extremely difficult task, particularly in scenarios where objects are attended to using fast-moving UAVs that need to robustly operate in real time. Typically the performance of these vision-based systems is affected by motion blur and geometric distortions, to name but two issues. Gimbal systems are thus essential to compensate for motion blur and ensure visual streams are stable. In this work, we investigate the advantages of active tracking approaches using a three-degrees-of-freedom (DoF) gimbal system mounted on UAVs. A method that utilizes joint movement and visual information for actively tracking spherical and planar objects in real time is proposed. Tracking methodologies are tested and evaluated in two different realistic Gazebo simulation environments: the first on 3D positional tracking (sphere) and the second on tracking of 6D poses (planar fiducial markers). We show that active object tracking is advantageous for UAV applications, first, by reducing motion blur, caused by fast camera motion and vibrations, and, second, by fixating the object of interest within the center of the field of view and thus reducing re-projection errors due to peripheral distortion. The results demonstrate significant object pose estimation accuracy improvements of active approaches when compared with traditional passive ones. More specifically, a set of experiments suggests that active gimbal tracking can increase the spatial estimation accuracy of known-size moving objects, under conditions of challenging motion patterns and in the presence of image distortion.

Contact lens‐related complications

The use of contact lens is very popular and its global market is growing. They have numerous applications, some well‐established and others still not consensual but which have been gaining more and more approval, namely refractive errors, dry eye management, post refractive surgery rehabilitation, persistent epithelial defects, cosmetic approaches and drug delivery systems. Unfortunately, there are some complications caused by their use, some of them sight threatening. The purpose of this presentation is to review these problems and to provide a better understanding of them.The major mechanisms implicated are numerous: trauma, decreased corneal oxygenation, reduced corneal and conjunctival lubrication, allergic and inflammatory responses and infection. However, depending on the complication we are talking about, there are other factors involved, such as contact lens‐related factors (material, design, fit and wearing schedule) and environmental factors (ocular surface condition, external environment, occupational factors, medications and compliance).The symptomatology experienced by patients ranges from hypoesthesia and mild conjunctival hyperemia to photophobia, contact lens intolerance and even decreased visual acuity.Many complications have been described. The most important (most common or most serious) are contact lens discomfort (CLD), dry eye, corneal deepithelialization (CD), sterile infiltrates (SI), corneal neovascularization (CNV), infectious keratitis (IK) and giant papillary conjunctivitis (GPC). Superior epithelial arcuate lesion, contact lens‐related peripheral ulcer, corneal distortion, hypoesthesia, ptosis, pinguecula, corneal edema, allergy aggravation, herpes reactivation and endothelial changes have also been described.CLD is an episodic or persistent adverse ocular sensation related to lens wear with a variable incidence in the literature, ranging from 23% to 94% in different series, being less common with soft lenses. Dry eye plays its role acting as a risk factor for CLD and/or as a consequence of contact lens use. CD manifests as punctate epithelial keratopathy, epithelial abrasions, foreign body tracks, corneal dellen, microcysts, vacuoles, mucin balls and dimple veiling. GPC is one of the most common adverse effects of contact lenses and the papillary reaction of the upper tarsal conjunctiva is the main feature of this entity. CNV is the formation of new vessels basically found in capillaries and venules of the pericorneal plexus, which may progress to the corneal stroma. They are much more associated with soft contact lenses, especially in extended wearers. Of note, contact lens use is one of the most common causes of CNV usually highlighted. SI are the result of an immunological reaction, often do not contain overlying epithelial defect or anterior chamber reaction and may manifest as stromal deep opacities. IK may be caused by bacteria, viruses, fungus or parasites and prompt immediate care and close revaluations to anticipate disastrous outcomes.Conservative measures play a role in almost all complications and their prevention, such as patient education, lubrication, contact lens exchange when applicable and modification of environmental factors. Addressing and learning how to prevent or quickly diagnose all these complications is crucial to prevent serious consequences.

Two-Dimensional Peripheral Refraction and Image Quality for Four Types of Refractive Surgeries.

To provide a comprehensive investigation of the optical quality across the visual field for current mainstream types of refractive surgeries. Sixty eyes from 60 adults who received refractive surgery of either femtosecond laser-assisted laser in situ keratomileusis (FS-LASIK), Q-value guided customized laser in situ keratomileusis (Q-LASIK), small incision lenticule extraction (SMILE), or Implantable Collamer Lens (ICL) (STAAR Surgical) implantation were included in this study. Refraction and optical aberrations from a visual field of horizontal 60° (from temporal 30° to nasal 30°) and vertical 36° (from superior 20° to inferior 16°) were measured using a custom-made Hartmann-Shack wavefront peripheral sensor. Refractive error, higher order aberrations, point spread function (PSF), and Strehl ratio were compared among these groups prior to and after the surgical procedures, respectively. All types of surgical procedures achieved an almost plano refraction in the central retina. This was also the case in the peripheral retina for the three types of laser refractive surgeries. However, residual peripheral relative hyperopic defocus was observed after ICL implantation. In all groups prior to the surgery, PSFs showed increasing distortion with eccentricity and arrow-like shape pointing toward the central fovea in the periphery in diagonals. Degradation of the PSFs was diminished by all three types of laser refractive surgeries, whereas ICL implantation made the peripheral distortion more prominent. Although ICL implantation produced a similar impact on refractive correction and objective optical quality in the central vision compared with other laser refractive surgeries, its outcome on the peripheral optics is different. The impact of this difference on visual performance deserves notice and warrants further investigation. [J Refract Surg. 2023;39(1):40-47.].

RETINAL VASCULAR BED AREA IN EYES WITH RETINAL VEIN OCCLUSION ON ULTRA-WIDEFIELD FLUORESCEIN ANGIOGRAPHY: WAVE Study.

To compute retinal vascular bed area (RVBA) in square millimeters on distortion corrected ultra-widefield fluorescein angiography images in eyes with retinal vein occlusion (RVO). Prospective observational study. The peripheral distortion of baseline ultra-widefield fluorescein angiography (Optos 200Tx) images of 30 patients with RVO from the WAVE study (NCT01710839) and 13 control eyes of normal subjects was corrected using the stereographic projection method to compute RVBA in square millimeters. In comparison with age- and sex-matched normal control eyes, eyes with RVO had a decreased global RVBA for the entire retina (50.5 ± 20.4 mm 2 vs. 62.6 ± 12.2 mm 2 , P = 0.023). Eyes with RVO and the unaffected fellow eye had a similar RVBA globally (50.5 ± 20.4 mm 2 vs. 46.2 ± 18.9 mm 2 , P = 0.523). The RVBA was observed to negatively correlate with nonperfusion area (R = -0.47, P = 0.009). However, RVBA was not related to the severity of macular edema ( P > 0.05). Eyes with RVO have a similar RVBA to the unaffected fellow eyes but with a reduction when compared with normal control eyes. Retinal vascular bed area appears to be a surrogate biomarker of retinal ischemia on ultra-widefield fluorescein angiography but not the extent of macular edema.

The impact of out-the-window size on air traffic controllers’ visual behaviours and response time on digital tower operations

Digital tower using video-panorama display permits the provision of air traffic services remotely without the need for a local physical tower. The recent growth of visual science has demonstrated the popular concept in respect of the size of display “bigger is better”. The aim of this research is to examine the sizes of Out-the-Window (OTW) panoramic displays and how they affect controller's visual behaviours, response time and workload. There are two validated OTW (43-inch vs 55-inch) which can potentially be implemented in the digital tower module. It is critical to investigate air traffic controllers’ cognitive demand and monitoring performance while interacting with different sizes of OTW in the digital tower module. This research recruited 15 qualified controllers working at a European regional airport. The results demonstrated that a 43-inch display was a better human-computer interaction in target identification than a 55-inch OTW panorama display. The subjective and objective approaches revealed that controllers’ visual behaviours and response times were difference while interacting with different sizes of OTW, but controllers’ workload did not show difference. The bigger screen presents bigger stimuli which are easier spotted by ATCOs, but it induces bigger amplitude of head and eye movements, bigger distortion on both edges of screen and longer response time on target identifications. System designers should be aware of the effects of peripheral vision and visual distortion on panorama displays while designing digital tower modules for the provision of future air traffic services.

Baseline retinal vascular bed area on ultra-wide field fluorescein angiography correlates with the anatomical outcome of diabetic macular oedema to ranibizumab therapy: two-year analysis of the DAVE Study.

To determine the relationship between baseline retinal non-perfusion area (NPA) and retinal vascular bed area (RVBA) on ultra-wide field fluorescein angiography (UWF FA) and long-term response to intravitreal ranibizumab therapy in diabetic macular oedema (DMO). A post-hoc, 2-year observational case series. Baseline UWF FA images (Optos 200Tx) of 40 eyes from 29 patients with diabetes mellitus and treatment naïve DMO in the DAVE (NCT01552408) study were montaged and stereographically projected at the Doheny Image Reading Center to adjust for peripheral distortion. The retinal vasculature was automatically extracted to calculate RVBA. NPA was manually delineated by two masked certified graders. RVBA and NPA were computed in mm2 automatically by adjusting for peripheral distortion and then correlated with the severity of DMO. While global NPA at baseline was not correlated to retinal thickness measurements, baseline NPA in the superior retina was associated with the macular volume (MV) improvement (P = 0.022). Multivariate analysis revealed a smaller RVBA at baseline was correlated with a better MV outcome at two-year follow-up after adjusting for confounding factors (P = 0.049). Eyes with smaller baseline RVBA appear to have a better long-term anatomic outcome of DMO.

NEW BIOMARKER QUANTIFYING THE EFFECT OF ANTI-VEGF THERAPY IN EYES WITH PROLIFERATIVE DIABETIC RETINOPATHY ON ULTRAWIDE FIELD FLUORESCEIN ANGIOGRAPHY: RECOVERY Study.

To quantify changes of the retinal vascular bed area (RVBA) in mm2 on stereographically projected ultrawide field fluorescein angiography images in eyes with proliferative diabetic retinopathy after antivascular endothelial growth factor injection. This is a prospective, observational study. The early-phase ultrawide field fluorescein angiography images (Optos 200Tx) of 40 eyes with proliferative diabetic retinopathy and significant nonperfusion obtained at baseline and after six months (NCT02863354) were stereographically projected by correcting peripheral distortion. The global retinal vasculature on ultrawide field fluorescein angiography was extracted for calculating RVBA by summing the real size (mm2) of all the pixels automatically. For the entire cohort, the global RVBA for the entire retina decreased from 67.1 ± 15.5 to 43.6 ± 18.8 mm2 after anti-VEGF treatment at six months (P < 0.001). In the subgroup receiving monthly anti-VEGF injections, the global RVBA decreased from 68.7 ± 16.2 to 33.9 ± 13.3 mm2 (P < 0.001). In the subgroup receiving anti-VEGF every three months, the global RVBA decreased from 65.6 ± 15.1 to 50.8 ± 19.3 mm2 (P = 0.004). RVBA seems to be a new biomarker to indicate efficiency of retinal vascular changes after anti-VEGF injection. Eyes with proliferative diabetic retinopathy and significant nonperfusion demonstrate reduced RVBA after anti-VEGF treatment.

Retinal vascular bed area on ultra-wide field fluorescein angiography indicates the severity of diabetic retinopathy

AimsTo quantify retinal vascular bed area (RVBA) in square millimetres on stereographically projected ultra-wide field (UWF) fluorescein angiography (FA) in eyes with diabetic retinopathy (DR).MethodsA prospective, observational study. Baseline Optos...

Objective analysis of perfluoropropane tamponade area after pars plana vitrectomy using ultra-widefield fundus stereographic projection images

To objectively analyze the gas tamponade area in patients with different concentrations of perfluoropropane (C3F8) after pars plana vitrectomy (PPV), retrospective analysis was performed in patients diagnosed with retinal detachment or macular hole and underwent PPV with C3F8 tamponade of two concentrations (14% and 20%). The ultra-widefield fundus (UWF) images at one and 10 days and four weeks postoperatively were corrected using stereographic projection to adjust peripheral distortion. The gas–fluid interface curvatures were delineated using UWF stereographic projection images, and the gas–fluid area ratio and estimated gas area were calculated at each concentration. Among 65 eyes, 30 were in the 14% group and 35 were in the 20% group. The gas–fluid area ratio was 0.71 in the 14% group and 0.83 in the 20% group at 10 days (p = 0.046) and 0.27 and 0.45, respectively, at four weeks postoperatively (p < 0.001). The estimated gas area was 52.56 and 60.82 mm2 at 10 days (p = 0.025) and 19.83 and 33.86 mm2 at four weeks (p < 0.001). The gas tamponade areas were objectively shown to be greater under the 20% concentration than the 14% concentration of C3F8 at 10 days and 4 weeks postoperatively using UWF stereographic projection images.

SEVERITY OF DIABETIC MACULAR EDEMA CORRELATES WITH RETINAL VASCULAR BED AREA ON ULTRA-WIDE FIELD FLUORESCEIN ANGIOGRAPHY: DAVE Study.

To quantify retinal nonperfusion area and retinal vascular bed area (RVBA) in mm on ultra-widefield fluorescein angiography in eyes with diabetic macular edema (DME) and explore their relationship with the severity of DME. Prospective, observational case series. Baseline ultra-widefield fluorescein angiography images of 40 eyes from 29 patients with treatment-naive DME who participated in the DAVE study (NCT01552408) were stereographically projected at Doheny Image Reading Center. The retinal vasculature was automatically extracted to calculate RVBA. Nonperfusion area was manually delineated by two masked certified graders. Retinal vascular bed area and nonperfusion area were computed in mm automatically by adjusting for peripheral distortion and then correlated with the severity of DME. The global RVBA for the entire retina in eyes with DME was increased compared with healthy controls (54.7 ± 16.6 mm vs. 37.2 ± 9.9 mm, P < 0.001) and correlated with the severity of DME (P < 0.05). Retinal ischemia (nonperfusion area) was nonuniformly distributed and not related to DME extent (P > 0.05). Eyes with DME have an increased RVBA compared with healthy controls. The severity of DME appears to be related to global RVBA, but not to retinal ischemia.

Hearing impairment is associated with enhanced neural tracking of the speech envelope

Elevated hearing thresholds in hearing impaired adults are usually compensated by providing amplification through a hearing aid. In spite of restoring hearing sensitivity, difficulties with understanding speech in noisy environments often remain. One main reason is that sensorineural hearing loss not only causes loss of audibility but also other deficits, including peripheral distortion but also central temporal processing deficits. To investigate the neural consequences of hearing impairment in the brain underlying speech-in-noise difficulties, we compared EEG responses to natural speech of 14 hearing impaired adults with those of 14 age-matched normal-hearing adults. We measured neural envelope tracking to sentences and a story masked by different levels of a stationary noise or competing talker. Despite their sensorineural hearing loss, hearing impaired adults showed higher neural envelope tracking of the target than the competing talker, similar to their normal-hearing peers. Furthermore, hearing impairment was related to an additional increase in neural envelope tracking of the target talker, suggesting that hearing impaired adults may have an enhanced sensitivity to envelope modulations or require a larger differential neural tracking of target versus competing talker to segregate speech from noise. Lastly, both normal-hearing and hearing impaired participants showed an increase in neural envelope tracking with increasing speech understanding. Hence, our results open avenues towards new clinical applications, such as neuro-steered prostheses as well as objective and automatic measurements of speech understanding performance.

Distribution and Location of Vortex Vein Ampullae in Healthy Human Eyes as Assessed by Ultra-Widefield Indocyanine Green Angiography

To study the number and distribution of vortex ampullae in healthy eyes using ultra-wide field (UWF) indocyanine green angiography (ICGA). Prospective, observational study. Thirty-six eyes of 36 healthy participants with no evidence of ocular or systemic disease. The UWF ICGA images (central and peripheral steered) were captured using the Optos California (Optos, Dunfermline, United Kingdom) instrument. The images were projected stereographically to correct for peripheral distortion and obtain accurate measurements. All images were graded and analyzed for number, location, and distance of the vortex vein ampullae from the center of optic nerve. Mean number and the distance of ampullae from the center of optic nerve in all quadrants. The mean number of ampullae observed by UWF ICGA was 8.0±2.1 (range, 5-13). The mean distance of a vortex vein ampulla from the optic nerve was 14.2±1.1 mm (range, 10.3-17.7 mm). The frequency of ampullae was higher in the superior and inferior quadrants than the nasal and temporal quadrants. Ampullae were never observed in the 3- or 9-o'clock meridians. Multiple regression analysis showed no relationship with age, gender, axial length, or ethnicity. Excellent intergrader reproducibility was found between graders with an intraclass correlation coefficient (distance measurements: intraclass correlation coefficient, 0.99; 95% CI, 0.979-0.999; P < 0.001; number of ampullae: intraclass correlation coefficient, 0.99; 95% CI, 0.988-0.999; P < 0.001). The number of discrete vortex vein ampullae that can be discerned by UWF ICGA in healthy individuals is greater frequently and substantially than the 4 that are traditionally thought to drain the major quadrants. Considerable variability in the number and position of the ampullae may be apparent in healthy individuals.

Relationship Between Retinal Fractal Dimension and Nonperfusion in Diabetic Retinopathy on Ultrawide-Field Fluorescein Angiography

To correlate fractal dimension (FD) of the retinal vasculature with the extent of retinal nonperfusion area in diabetic retinopathy (DR) on ultrawide-field fluorescein angiography (FA). Cross-sectional study. Baseline Optos 200Tx ultrawide-field FA images of 80 eyes with DR from the DAVE (NCT01552408) and RECOVERY (NCT02863354) studies were stereographically projected at the Doheny Image Reading Center. The retinal vasculature was extracted from an early-phase FA frame by exploiting the elongated nature of the vessels and then skeletonized for calculation of FD using a box-counting method. The nonperfusion area was delineated by 2 independent, reading center-certified graders who were masked to the study groups and who were using a standardized protocol and then computed in millimeters squared. While no difference in FD was observed for the entire retina in DR compared with normal control subjects, a significantly smaller FD was found in the far-periphery of the DR eyes (P < .001). FD for the entire retina was negatively associated with global nonperfusion area (R=-0.44; P < .001), and this relationship was also present within the 3 concentric retinal zones (posterior: R=-0.31, P= .016; midperiphery: R=-0.35, P= .007; and far periphery: R=-0.31, P= .015). Peripheral FD on ultrawide-field FA is reduced in DR eyes compared with normal eyes and is correlated with severity of retinal nonperfusion. FD can be calculated automatically without the need for correction of peripheral distortion, and therefore it may prove to be a useful surrogate biomarker when precise quantification of nonperfusion is not feasible.

Image content is more important than Bouma's Law for scene metamers.

We subjectively perceive our visual field with high fidelity, yet peripheral distortions can go unnoticed and peripheral objects can be difficult to identify (crowding). Prior work showed that humans could not discriminate images synthesised to match the responses of a mid-level ventral visual stream model when information was averaged in receptive fields with a scaling of about half their retinal eccentricity. This result implicated ventral visual area V2, approximated 'Bouma's Law' of crowding, and has subsequently been interpreted as a link between crowding zones, receptive field scaling, and our perceptual experience. However, this experiment never assessed natural images. We find that humans can easily discriminate real and model-generated images at V2 scaling, requiring scales at least as small as V1 receptive fields to generate metamers. We speculate that explaining why scenes look as they do may require incorporating segmentation and global organisational constraints in addition to local pooling.

Classification of Regions of Nonperfusion on Ultra-widefield Fluorescein Angiography in Patients with Diabetic Macular Edema

To classify retinal nonperfusion regions (NPRs) in patients with diabetic macular edema (DME) and assess the relationship with severity of DME. Prospective, observational case series. Forty eyes of 29 patients with treatment-naïve center-involved macular edema secondary to diabetes mellitus were included (The DAVE study, NCT01552408) in this analysis. Ultra-widefield fluorescein angiography (UWF FA) images were transmitted to the Doheny Image Reading Center, where they were corrected using stereographic projection to adjust for peripheral distortion. Two independent, certified graders manually evaluated the NPR and classified the nonperfusion as being associated with leakage or without leakage. The size of these 2 subtypes of NPR were computed in mm2 and assessed across the entire retina and within 3 concentric retinal zones. The relationship between subtype of NPR and the severity of DME was assessed. In 40 eyes with treatment-naïve DME, visual acuity was significantly correlated with central macular thickness (CMT) and macular volume (MV). The NPR with leakage was positively correlated with CMT (R= 0.408, P= .009) and MV (R= 0.399, P= .011), whereas the NPR without leakage was negatively correlated with CMT (R=-0.468, P= .002) and MV (R=-0.473, P= .002). The NPR with leakage in the posterior region was significantly greater compared to the mid-periphery and the far periphery (P < .001), whereas the NPR without leakage was significantly greater in the mid-periphery compared with the far periphery or the posterior region (P= .001). In patients with DME, the severity of DME appears to be positively correlated with NPR with leakage but negatively correlated with NPR without leakage. These findings may have implications for the pathophysiology of DME and the design of protocols for targeted laser in these eyes.

Gas flow characteristics of argon inductively coupled plasma and advections of plasma species under incompressible and compressible flows** Project supported by the National Natural Science Foundations of China (Grant No. 11305023). The author is deeply indebted to the Dalian University of Technology for providing the authority of utilizing the COMSOL software.

In this work, incompressible and compressible flows of background gas are characterized in argon inductively coupled plasma by using a fluid model, and the respective influence of the two flows on the plasma properties is specified. In the incompressible flow, only the velocity variable is calculated, while in the compressible flow, both the velocity and density variables are calculated. The compressible flow is more realistic; nevertheless, a comparison of the two types of flow is convenient for people to investigate the respective role of velocity and density variables. The peripheral symmetric profile of metastable density near the chamber sidewall is broken in the incompressible flow. At the compressible flow, the electron density increases and the electron temperature decreases. Meanwhile, the metastable density peak shifts to the dielectric window from the discharge center, besides for the peripheral density profile distortion, similar to the incompressible flow. The velocity profile at incompressible flow is not altered when changing the inlet velocity, whereas clear peak shift of velocity profile from the inlet to the outlet at compressible flow is observed as increasing the gas flow rate. The shift of velocity peak is more obvious at low pressures for it is easy to compress the rarefied gas. The velocity profile variations at compressible flow show people the concrete residing processes of background molecule and plasma species in the chamber at different flow rates. Of more significance is it implied that in the usual linear method that people use to calculate the residence time, one important parameter in the gas flow dynamics, needs to be rectified. The spatial profile of pressure simulated exhibits obvious spatial gradient. This is helpful for experimentalists to understand their gas pressure measurements that are always taken at the chamber outlet. At the end, the work specification and limitations are listed.

Novel grid combined with peripheral distortion correction for ultra-widefield image grading of age-related macular degeneration.

PurposeEyes with age-related macular degeneration (AMD) often harbor pathological changes in the retinal periphery and perimacular region. These extramacular changes have not been well classified, but may be phenotypically and functionally relevant. The purpose of this study was to demonstrate a novel grid to systematically study peripheral retinal abnormalities in AMD using geometric distortion-corrected ultra-widefield (UWF) imaging.MethodsThis is a cross-sectional observational case series. Consecutive patients with AMD without any other coexisting vitreoretinal disease and control patients over age 50 without AMD or any other vitreoretinal disease were imaged using Optos 200 Tx. Captured 200° UWF images were corrected for peripheral geometric distortion using Optos transformation software. A newly developed grid to study perimacular and peripheral abnormalities in AMD was then projected onto the images.ResultsPeripheral and perimacular changes such as drusen, retinal pigment epithelium changes and atrophy were found in patients with AMD. The presented grid in conjunction with geometric distortion-corrected UWF images allowed for systematic study of these peripheral changes in AMD.ConclusionWe present a novel grid to study peripheral and posterior pole changes in AMD. The grid is unique in that it adds a perimacular zone, which may be important in characterizing certain phenotypes in AMD. Our UWF images were corrected for geometric peripheral distortion to accurately reflect the anatomical dimensions of the retina. This grid offers a reliable and reproducible foundation for the exploration of peripheral retinal pathology associated with AMD.