Reinforcement learning-based dynamic obstacle avoidance and integration of path planning.

Deep reinforcement learning has the advantage of being able to encode fairly complex behaviors by collecting and learning empirical information. In the current study, we have proposed a framework for reinforcement learning in decentralized collision avoidance where each agent independently makes its decision without communication with others. In an environment exposed to various kinds of dynamic obstacles with irregular movements, mobile robot agents could learn how to avoid obstacles and reach a target point efficiently. Moreover, a path planner was integrated with the reinforcement learning-based obstacle avoidance to solve the problem of not finding a path in a specific situation, thereby imposing path efficiency. The robots were trained about the policy of obstacle avoidance in environments where dynamic characteristics were considered with soft actor critic algorithm. The trained policy was implemented in the robot operating system (ROS), tested in virtual and real environments for the differential drive wheel robot to prove the effectiveness of the proposed method. Videos are available at https://youtu.be/xxzoh1XbAl0.

Determination of Vehicle Trajectory through Optimization of Vehicle Bounding Boxes Using a Convolutional Neural Network.

In this manuscript, a new method for the determination of vehicle trajectories using an optimal bounding box for the vehicle is developed. The vehicle trajectory is extracted using images acquired from a camera installed at an intersection based on a convolutional neural network (CNN). First, real-time vehicle object detection is performed using the YOLOv2 model, which is one of the most representative object detection algorithms based on CNN. To overcome the inaccuracy of the vehicle location extracted by YOLOv2, the trajectory was calibrated using a vehicle tracking algorithm such as a Kalman filter and intersection-over-union (IOU) tracker. In particular, we attempted to correct the vehicle trajectory by extracting the center position based on the geometric characteristics of a moving vehicle according to the bounding box. The quantitative and qualitative evaluations indicate that the proposed algorithm can detect the trajectories of moving vehicles better than the conventional algorithm. Although the center points of the bounding boxes obtained using the existing conventional algorithm are often outside of the vehicle due to the geometric displacement of the camera, the proposed technique can minimize positional errors and extract the optimal bounding box to determine the vehicle location.

An Optical Coherence Tomography Angiography Study of the Relationship Between Foveal Avascular Zone Size and Retinal Vessel Density.

Purpose: To assess the relationship between the size of the foveal avascular zone (FAZ; area and perimeter) and vessel density (VD) at various retinal regions using optical coherence tomography angiography (OCTA) in patients with open-angle glaucoma (OAG). Methods: In this retrospective cross-sectional study, OAG eyes were grouped according to the presence/absence of central visual field (CVF) defects. A control group of normal eyes was also included. OCTA images were obtained from the optic nerve (4.5 × 4.5 mm2) and macular (3 × 3 mm2) area, in which VDs were measured in the circumpapilla, parafovea, and fovea regions. Partial correlation analyses between FAZ parameters representing size and VDs at different retinal regions were performed. The correlation between FAZ parameters and macular ganglion cell-inner plexiform layer thickness (mGCIPLT) and CVF mean sensitivity (MS) was also assessed. For spatial correspondence, correlations between FAZ parameters and corresponding VD, mGCIPLT, and CVF-MS measurements were assessed at each hemiretina. Results: A total of 126 OAG eyes and 40 controls were reviewed. Overall, FAZ parameters showed statistically significant correlations with VDs measured at the fovea, parafovea, and circumpapilla (FAZ area: r = -0.603, -0.385, -0.256; P < 0.001, < 0.001, and 0.003, respectively). These correlations were observed regardless of the presence of CVF defects (all P < 0.05). FAZ size showed significant spatial correlations with VD, mGCIPLT, and CVF-MS measurements at each hemiretina. Conclusions: OCTA-derived FAZ area and perimeter showed statistically significant correlations with VDs measured at various retinal locations with spatial correspondence in OAG.

Controllable Switching Filaments Prepared via Tunable and Well-Defined Single Truncated Conical Nanopore Structures for Fast and Scalable SiOx Memory.

The controllability of switching conductive filaments is one of the central issues in the development of reliable metal-oxide resistive memory because the random dynamic nature and formation of the filaments pose an obstacle to desirable switching performance. Here, we introduce a simple and novel approach to control and form a single silicon nanocrystal (Si-NC) filament for use in SiOx memory devices. The filament is formed with a confined vertical nanoscale gap by using a well-defined single vertical truncated conical nanopore (StcNP) structure. The physical dimensions of the Si-NC filaments such as number, size, and length, which have a significant influence on the switching properties, can be simply engineered by the breakdown of an Au wire through different StcNP structures. In particular, we demonstrate that the designed SiOx memory junction with a StcNP of pore depth of ∼75 nm and a bottom diameter of ∼10 nm exhibited a switching speed of up to 6 ns for both set and reset process, significantly faster than reported SiOx memory devices. The device also exhibited a high ON-OFF ratio, multistate storage ability, acceptable endurance, and retention stability. The influence of the physical dimensions of the StcNP on the switching features is discussed based on the simulated temperature profiles of the Au wire and the nanogap size generated inside the StcNP structure during electromigration.

Glaucoma Diagnostic Capabilities of Foveal Avascular Zone Parameters Using Optical Coherence Tomography Angiography According to Visual Field Defect Location.

PURPOSE: To assess the diagnostic ability of foveal avascular zone (FAZ) parameters to discriminate glaucomatous eyes with visual field defects (VFDs) in different locations (central vs. peripheral) from normal eyes. PATIENTS AND METHODS: Totally, 125 participants were separated into 3 groups: normal (n=45), glaucoma with peripheral VFD (PVFD, n=45), and glaucoma with central VFD (CVFD, n=35). The FAZ area, perimeter, and circularity and parafoveal vessel density were calculated from optical coherence tomography angiography images. The diagnostic ability of the FAZ parameters and other structural parameters was determined according to glaucomatous VFD location. Associations between the FAZ parameters and central visual function were evaluated. RESULTS: A larger FAZ area and longer FAZ perimeter were observed in the CVFD group than in the PVFD and normal groups. The FAZ area, perimeter, and circularity were better in differentiating glaucomatous eyes with CVFDs from normal eyes [areas under the receiver operating characteristic curves (AUC), 0.78 to 0.88] than in differentiating PVFDs from normal eyes (AUC, 0.51 to 0.64). The FAZ perimeter had a similar AUC value to the circumpapillary retinal nerve fiber layer and macular ganglion cell-inner plexiform layer thickness for differentiating eyes with CVFDs from normal eyes (all P>0.05, the DeLong test). The FAZ area was significantly correlated with central visual function (ß=-112.7, P=0.035, multivariate linear regression). CONCLUSIONS: The FAZ perimeter had good diagnostic capability in differentiating glaucomatous eyes with CVFDs from normal eyes, and may be a potential diagnostic biomarker for detecting glaucomatous patients with CVFDs.

Quantitative optical coherence tomography angiography of macular vascular structure and foveal avascular zone in glaucoma.

OBJECTIVE: The study aimed to evaluate the quantitative characteristics of the macular vessel density (VD) and foveal avascular zone (FAZ) in glaucoma using optical coherence tomography angiography (OCT-A). DESIGN: Cross-sectional, age- and sex-matched case-control study. METHODS: Fifty-two eyes of 52 patients with primary open angle glaucoma and 52 eyes from 52 healthy participants were recruited retrospectively. OCT-A was performed on a 3 x 3-mm macular region centered on the fovea. OCT-A scans were manually graded to define the FAZ. Parafoveal VD in superficial and deep retina were analyzed in the circular- and quadrant-segmented zone. The FAZ parameters included size, perimeter, and circularity index. The regression analysis among VD and FAZ-related parameters and ocular parameters was performed, and the diagnostic ability was calculated with refractive error adjusted. RESULTS: For both groups, the mean age and the sex ratio was not different between groups. With refractive error adjusted, the average macular VD was lower in glaucoma than in the control group for superficial (P = 0.013), deep (P<0.001), and the whole retina (P = 0.002). There were increased FAZ perimeter and decreased FAZ circularity index in glaucoma when compared with controls (P<0.001). In the multivariate regression models, FAZ circularity index were significantly associated with decreased peripapillary RNFL thickness (P = 0.007) and macular GCIPL thickness (P = 0.009) measured by OCT. The refractive-error adjusted area under receiver operating characteristics was highest for FAZ circularity index (0.905; 95% CI, 0.844-0.966), followed by temporal deep retinal VD (0.870; 95% CI, 0.803-0.937) and FAZ perimeter (0.858; 95% CI, 0.784-0.932). CONCLUSIONS: Decreased macular VD, increased FAZ perimeter, and decreased FAZ circularity index were observed in eyes with glaucoma using OCT-A. With refractive error adjusted, these parameters showed considerable diagnostic value for glaucoma. FAZ circularity index may be a novel biomarker representing disruption of the parafoveal capillary network in glaucoma, as supported by its association with structural parameters.

Regional vascular density-visual field sensitivity relationship in glaucoma according to disease severity.

AIMS: To study whether there are global and regional relationships between peripapillary vascular density (pVD) assessed by optical coherence tomography angiography (OCT-A) and visual field (VF) mean sensitivity at different glaucoma stages. METHODS: Microvascular images and peripapillary retinal nerve fibre layer (pRNFL) thicknesses were obtained using a Cirrus OCT-A device in 91 glaucoma subjects. The pVD was measured at various spatial locations according to the Garway-Heath map, using a MATLAB software (The MathWorks, Natick, Massachusetts). VF mean sensitivity (VFMS) was recorded in the 1/L scale. Global and regional vasculature-function (pVD vs VFMS) relationships were assessed in separate patient groups at mild and moderate-to-advanced stages of glaucoma. RESULTS: The pVDs at superotemporal and inferotemporal regions were significantly associated with corresponding VFMS in mild glaucoma (p<0.05). In moderate-to-advanced glaucoma, there were significant associations between pVD and VFMS, regardless of location. The association between global pVD and VFMS was significantly stronger than that between global pRNFL thickness and VFMS in moderate-to-advanced stage glaucoma (p <0.05). CONCLUSION: Global and regional pVD measured by OCT-A was significantly associated with corresponding VFMS in moderate-to-advanced glaucoma. OCT-A may be useful in monitoring glaucoma at various stages.

Alterations of the Foveal Avascular Zone Measured by Optical Coherence Tomography Angiography in Glaucoma Patients With Central Visual Field Defects.

Purpose: To investigate whether the area and shape of the foveal avascular zone (FAZ) as assessed by optical coherence tomography angiography (OCTA) are altered in glaucomatous eyes with central visual field defects (CVFDs). Methods: A total of 78 patients with open-angle glaucoma with central or peripheral visual field defects (PVFDs) confined to a single hemifield were studied retrospectively. Foveal avascular zone area and circularity were measured using OCTA images from the superficial retinal layer. Central retinal visual field (VF) sensitivity using Swedish Interactive Threshold Algorithm 24-2 VF and macular ganglion cell-inner plexiform layer (mGCIPL) thickness were measured. The FAZ area between VF-affected hemimacular segments and VF-unaffected hemimacular segments in eyes with CVFDs and matched hemimacular segments of eyes with PVFDs were compared. Factors associated with the presence and severity of CVFD at initial presentation were determined. Results: Eyes with CVFDs showed a significantly larger FAZ area, lower FAZ circularity, and lower mGCIPL thickness than the PVFD group. The mean hemi-FAZ area of VF-affected hemimaculas in eyes with CVFDs was significantly larger than that of the PVFD group (0.256 ± 0.07 mm2 vs. 0.184 ± 0.07 mm2) and the VF-unaffected hemimaculas of the CVFD group (0.179 ± 0.06 mm2; P < 0.05). Age, mean deviation, mGCIPL thickness, FAZ area, and circularity were associated with CVFDs (P < 0.05). Conclusions: Microcirculatory alterations in the perifovea are spatially correlated with central VF loss. Loss of FAZ circularity was significantly associated with presence of CVFD, whereas FAZ area was significantly associated with severity of CVFD.

Association Between Nocturnal Blood Pressure Dips and Optic Disc Hemorrhage in Patients With Normal-Tension Glaucoma.

PURPOSE: To investigate the effect of nocturnal blood pressure (BP) dips on the occurrence of optic disc hemorrhage (ODH) in normal-tension glaucoma (NTG) patients and determine whether ODH is associated with greater likelihood of visual field progression (VFP). DESIGN: Prospective case-control study. METHODS: This study enrolled 698 eyes of 349 consecutive NTG patients who were ≥40 years old, underwent 24-hour intraocular pressure and ambulatory BP monitoring in the habitual position, were examined for ODH every 4-6 months with optic disc photography, and had ≥5 reliable visual field tests with minimum follow-up of 3 years. NTG patients were classified into 2 groups: "nonphysiologic" dippers, including nondippers and overdippers, and "physiologic" dippers. Odds ratios for the association between the "nonphysiologic" group and ODH were calculated using logistic regression models. Kaplan-Meier analyses were performed to compare outcomes with reference to the presence of ODH for VFP. RESULTS: Overall, ODH and VFP were detected in 107 (15.3%) eyes and 60 (8.6%) eyes among total 698 eyes, respectively. Overdippers showed a significantly greater frequency of ODH than nondippers or dippers. Being an overdipper was a significant and an independent risk factor for ODH occurrence during follow-up. The rates of VFP were 6%, 7%, and 24% for dippers, nondippers, and overdippers, respectively. Eyes with ODH were associated with greater likelihoods of subsequent VFP than those without. VFP occurred only in eyes with ODH. CONCLUSIONS: Being an overdipper is a significant risk factor for ODH in NTG eyes. The detection of ODH during follow-up is a potent predictor of future VFP.

Difference in tongue strength using visual feedback in healthy adults.

[Purpose] This study investigated the difference in tongue strength with and without visual feedback in healthy adults. [Subjects and Methods] A total of 30 healthy adults were recruited. We measured the strength of the anterior region of the tongue before and after applying visual feedback using the Iowa Oral Performance Instrument. [Results] The tongue strength was measured as 45.5 ± 9.3 kilopascals with visual feedback and 41.1 ± 8.6 kilopascals without visual feedback, showing a statistically significant difference. [Conclusion] Visual feedback may be an effective tool for increasing the strength of the tongue.

Oxidative Dimerization of PHD2 is Responsible for its Inactivation and Contributes to Metabolic Reprogramming via HIF-1α Activation.

Prolyl hydroxylase domain protein 2 (PHD2) belongs to an evolutionarily conserved superfamily of 2-oxoglutarate and Fe(II)-dependent dioxygenases that mediates homeostatic responses to oxygen deprivation by mediating hypoxia-inducible factor-1α (HIF-1α) hydroxylation and degradation. Although oxidative stress contributes to the inactivation of PHD2, the precise molecular mechanism of PHD2 inactivation independent of the levels of co-factors is not understood. Here, we identified disulfide bond-mediated PHD2 homo-dimer formation in response to oxidative stress caused by oxidizing agents and oncogenic H-ras(V12) signalling. Cysteine residues in the double-stranded ß-helix fold that constitutes the catalytic site of PHD isoforms appeared responsible for the oxidative dimerization. Furthermore, we demonstrated that disulfide bond-mediated PHD2 dimerization is associated with the stabilization and activation of HIF-1α under oxidative stress. Oncogenic H-ras(V12) signalling facilitates the accumulation of HIF-1α in the nucleus and promotes aerobic glycolysis and lactate production. Moreover, oncogenic H-ras(V12) does not trigger aerobic glycolysis in antioxidant-treated or PHD2 knocked-down cells, suggesting the participation of the ROS-mediated PHD2 inactivation in the oncogenic H-ras(V12)-mediated metabolic reprogramming. We provide here a better understanding of the mechanism by which disulfide bond-mediated PHD2 dimerization and inactivation result in the activation of HIF-1α and aerobic glycolysis in response to oxidative stress.

Systemic and Ocular Hemodynamic Risk Factors in Glaucoma.

Primary open angle glaucoma (POAG) is a multifactorial disease characterized by progressive retinal ganglion cell death and visual field loss. It is known that alterations in intraocular pressure (IOP), blood pressure (BP), and ocular perfusion pressure (OPP) can play a significant role in the pathogenesis of the disease. Impaired autoregulatory capacity of ocular blood vessels may render tissues vulnerable to OPP changes and potentially harmful tissue ischemia-reperfusion damage. Vascular risk factors should be considered more important in a subgroup of patients with POAG, and especially in patients with normal tension glaucoma (NTG) with evidence of unphysiological BP response. For example, reduction of BP during the nighttime has an influence on OPP, and increased circadian OPP fluctuation, which might stand for unstable ocular blood flow, has been found to be the consistent risk factor for NTG development and progression. Central visual field may be affected more severely than peripheral visual field in NTG patients with higher 24-hour fluctuation of OPP. This review will discuss the current understanding of allegedly major systemic and ocular hemodynamic risk factors for glaucoma including systemic hypertension, arterial stiffness, antihypertensive medication, exaggerated nocturnal hypotension, OPP, and autonomic dysregulation.

Relationship between daytime variability of blood pressure or ocular perfusion pressure and glaucomatous visual field progression.

PURPOSE: To study daytime or nighttime variability of mean arterial pressure and ocular perfusion pressure in untreated normal-tension glaucoma (NTG) patients and determine whether increased short-term mean arterial pressure and/or ocular perfusion pressure variability are associated with greater risk of visual field (VF) progression. DESIGN: Longitudinal, retrospective, observational study. METHODS: This study enrolled 237 eyes of 237 untreated NTG patients who underwent 24-hour intraocular pressure and ambulatory blood pressure monitoring in the habitual position, and had ≥5 reliable VF tests during follow-up. Kaplan-Meier analyses were performed to compare outcomes with reference to the level of short-term mean arterial pressure and ocular perfusion pressure standard deviation for VF deterioration. Hazard ratios for the association between clinical factors, including short-term mean arterial pressure and ocular perfusion pressure standard deviation, and VF progression were obtained using Cox proportional hazards models. RESULTS: Over-dipper NTG patients showed significantly larger daytime and nighttime mean arterial pressure and ocular perfusion pressure standard deviation than non-dippers or dippers. Both increased daytime and nighttime mean arterial pressure or ocular perfusion pressure standard deviation were associated with greater VF progression probabilities. Increased daytime mean arterial pressure or ocular perfusion pressure standard deviation was a significant predictor of subsequent VF progression (P = .023 and P < .001, respectively). CONCLUSIONS: Over-dipper NTG eyes showed significantly higher daytime or nighttime mean arterial pressure and ocular perfusion pressure variabilities than non-dipper and dipper NTG eyes. Increased daytime mean arterial pressure and ocular perfusion pressure standard deviation at baseline were significant predictors of future VF progression in NTG.

Anti-Inflammatory Action of an Antimicrobial Model Peptide That Suppresses the TRIF-Dependent Signaling Pathway via Inhibition of Toll-Like Receptor 4 Endocytosis in Lipopolysaccharide-Stimulated Macrophages.

Antimicrobial peptides (AMPs), also called host defense peptides, particularly those with amphipathic helical structures, are emerging as target molecules for therapeutic development due to their immunomodulatory properties. Although the antimicrobial activity of AMPs is known to be exerted primarily by permeation of the bacterial membrane, the mechanism underlying its anti-inflammatory activity remains to be elucidated. We report potent anti-inflammatory activity of WALK11.3, an antimicrobial model peptide with an amphipathic helical conformation, in lipopolysaccharide (LPS)-stimulated RAW264.7 cells. This peptide inhibited the expression of inflammatory mediators, including nitric oxide, COX-2, IL-1ß, IL-6, INF-ß, and TNF-α. Although WALK11.3 did not exert a major effect on all downstream signaling in the MyD88-dependent pathway, toll-like receptor 4 (TLR4)- mediated pro-inflammatory signals were markedly attenuated in the TRIF-dependent pathway due to inhibition of the phosphorylation of STAT1 by attenuation of IRF3 phosphorylation. WALK11.3 specifically inhibited the endocytosis of TLR4, which is essential for triggering TRIF-mediated signaling in macrophage cells. Hence, we suggest that specific interference with TLR4 endocytosis could be one of the major modes of the anti-inflammatory action of AMPs. Our designed WALK11 peptides, which possess both antimicrobial and anti-inflammatory activities, may be promising molecules for the development of therapies for infectious inflammation.

Automatic extraction of optimal endmembers from airborne hyperspectral imagery using iterative error analysis (IEA) and spectral discrimination measurements.

Pure surface materials denoted by endmembers play an important role in hyperspectral processing in various fields. Many endmember extraction algorithms (EEAs) have been proposed to find appropriate endmember sets. Most studies involving the automatic extraction of appropriate endmembers without a priori information have focused on N-FINDR. Although there are many different versions of N-FINDR algorithms, computational complexity issues still remain and these algorithms cannot consider the case where spectrally mixed materials are extracted as final endmembers. A sequential endmember extraction-based algorithm may be more effective when the number of endmembers to be extracted is unknown. In this study, we propose a simple but accurate method to automatically determine the optimal endmembers using such a method. The proposed method consists of three steps for determining the proper number of endmembers and for removing endmembers that are repeated or contain mixed signatures using the Root Mean Square Error (RMSE) images obtained from Iterative Error Analysis (IEA) and spectral discrimination measurements. A synthetic hyperpsectral image and two different airborne images such as Airborne Imaging Spectrometer for Application (AISA) and Compact Airborne Spectrographic Imager (CASI) data were tested using the proposed method, and our experimental results indicate that the final endmember set contained all of the distinct signatures without redundant endmembers and errors from mixed materials.

Relationship between 24-hour mean ocular perfusion pressure fluctuation and rate of paracentral visual field progression in normal-tension glaucoma.

PURPOSE: To investigate the relationship between unstable mean ocular perfusion pressure (MOPP) and the rate of paracentral visual field (PVF) progression in patients with medically treated normal-tension glaucoma (NTG). METHODS: The data of 157 eyes of 122 patients with NTG who were followed for more than 6 years (mean follow-up, 8.7 years ± 12.6 months) and had more than 5 reliable standard visual field (VF) tests were analyzed retrospectively. Groups in the highest, middle, and lowest tertiles of 24-hour MOPP fluctuation (HMF, MMF, and LMF, respectively) were compared in terms of rates of change of mean thresholds in the central 10° (PVF), 10° to 24°, and global areas by using a linear mixed model. Clinical factors associated with rapid PVF progression were also investigated. RESULTS: The LMF and HMF groups did not differ significantly in the mean global rate of VF changes (-0.52 vs. -0.71 dB/y; P = 0.07). The HMF group had a significantly faster progression of VF defects in the central 10° area than the LMF group (-1.02 vs. -0.54 dB/y; P < 0.001) but did not differ in terms of progression of VF defects in the peripheral 10° to 24° area (-0.39 vs. -0.495 dB/y; P = 0.425). PVF progression was significantly associated with 24-hour MOPP fluctuation (ß = -0.31, P < 0.001) and VF damage severity at initial presentation (ß = 0.134, P = 0.011). CONCLUSIONS: Medically treated NTG eyes with greater 24-hour MOPP fluctuations (HMF) had faster PVF defect progression than eyes with stable 24-hour MOPP (LMF). Twenty-four hour MOPP fluctuation associated significantly with PVF progression velocity.

Ocular pulse amplitude as a dynamic parameter and its relationship with 24-h intraocular pressure and blood pressure in glaucoma.

Abnormal ocular blood flow (OBF) has been suspected as one of the underlying mechanisms of glaucoma. The ocular pulse amplitude (OPA) is considered a possible surrogate parameter for ocular blood flow (OBF) measurement and has been studied in its association with glaucoma. Although there have been several studies that reported various ocular and systemic factors in association with OPA, all of these studies were based on a single measurement of these factors as well as OPA. The purpose of this study was to determine the 24-h (h) dynamic variability and any associations between OPA and intraocular pressure (IOP) and blood pressure (BP) variables using 24-h data collected from untreated patients with normal-tension glaucoma (NTG). One hundred and forty-four patients with NTG were consecutively enrolled. All patients underwent 24-h monitoring of IOP, OPA, and BP variables. A cosinor model was used to describe the patterns and statistical significance of the 24-h OPA rhythm, as well as the IOP and BP variables. Associations between 24-h OPA data, IOP and BP variables, and ocular and demographic factors were also assessed using the generalized estimating equation. Over the course of 24-h, OPA (p = 0.007) demonstrated significant dynamic diurnal rhythms that were similar to the other dynamic variables (all p < 0.05). Based on the 24-h data, IOP (p < 0.001), arterial pulse pressure (p = 0.034), and the spherical equivalent (p < 0.001) positively correlated with the OPA, whilst male sex (p < 0.001) negatively correlated with the OPA. These results indicate that OPA is primarily influenced by IOP as well as arterial pulse pressure, spherical equivalent, and gender. In conclusion, OPA is a dynamic ocular parameter that demonstrates a 24-h short-time fluctuation in NTG patients.

Factors affecting ocular pulse amplitude in eyes with open angle glaucoma and glaucoma-suspect eyes.

PURPOSE: To investigate the associations between ocular pulse amplitude (OPA) as measured by dynamic contour tonometry (DCT) and ocular and systemic factors in patients with open angle glaucoma (OAG) and in glaucoma suspects. METHODS: One hundred and seventy-three glaucoma-suspect patients were consecutively enrolled. All subjects underwent intraocular pressure (IOP) measurement by DCT and Goldmann applanation tonometry (GAT), OPA measurement by DCT, Humphrey visual field (HVF) examination and central corneal thickness measurements. Arterial pulse amplitude (APA) and ocular perfusion pressure (OPP) were defined as the difference between systolic and diastolic BP and the difference between mean arterial pressure and IOP, respectively. All subjects also completed a systemized questionnaire on systemic vascular morbidities. RESULTS: Seventy-four eyes were diagnosed with OAG, based on HVF results. The overall mean CCT was 538.2±37.6 µm. In all 173 eyes, OPA was associated with spherical equivalent (SE, p<0.001) and with IOP by GAT (p=0.013) by multivariate analysis. Multivariate analysis of the 77 subgroup eyes of patients for whom BP parameters were available also revealed that OPA was associated with SE (p=0.007) and with IOP by GAT (p<0.001). When the subjects were classified into the groups with low, intermediate and high cardiovascular risk based on the questionnaire, there was no difference in OPA among these groups (p>0.05). CONCLUSIONS: Ocular pulse amplitude was associated with IOP measured by GAT and SE in patients with OAG and in glaucoma suspects. There was neither significant correlation between systemic hemodynamic parameters and OPA, nor difference of OPA in patients with different cardiovascular risk. OPA is primarily a measure of pressure, and there are certain limitations towards its use as a hemodynamic index.