Evaluating Responses of Circulatory Systems, Sweating and Pupil Diameter to Postural Change

2018 ◽  
Vol 138 (9) ◽  
pp. 1141-1147
Author(s):  
Munemichi Tateyama ◽  
Ikuhide Kinoshita ◽  
Akihiko Akao ◽  
Sho Shirasaka ◽  
Takashi Numata ◽  
...  
Keyword(s):  
Pupil Diameter ◽  
Postural Change

scholarly journals Experimental Analysis of Driver Visual Characteristics in Urban Tunnels

2021 ◽  
Vol 11 (9) ◽  
pp. 4274
Author(s):  
Song Fang ◽  
Jianxiao Ma
Keyword(s):  
Traffic Safety ◽  
Clustering Algorithm ◽  
Pupil Diameter ◽  
Data Fitting ◽  
Eye Tracker ◽  
Tunnel Length ◽  
Point Distribution ◽  
Change Rate ◽  
Visual Characteristics ◽  
Diameter Change

Through an urban tunnel-driving experiment, this paper studies the changing trend of drivers’ visual characteristics in tunnels. A Tobii Pro Glasses 2 wearable eye tracker was used to measure pupil diameter, scanning time, and fixation point distribution of the driver during driving. A two-step clustering algorithm and the data-fitting method were used to analyze the experimental data. The results show that the univariate clustering analysis of the pupil diameter change rate of drivers has poor discrimination because the pupil diameter change rate of drivers in the process of “dark adaptation” is larger, while the pupil diameter change rate of drivers in the process of “bright adaptation” is relatively smooth. The univariate and bivariate clustering results of drivers’ pupil diameters were all placed into three categories, with reasonable distribution and suitable differentiation. The clustering results accurately corresponded to different locations of the tunnel. The clustering method proposed in this paper can identify similar behaviors of drivers at different locations in the transition section at the tunnel entrance, the inner section, and the outer area of the tunnel. Through data-fitting of drivers’ visual characteristic parameters in different tunnels, it was found that a short tunnel, with a length of less than 1 km, has little influence on visual characteristics when the maximum pupil diameter is small, and the percentage of saccades is relatively low. An urban tunnel with a length between 1 and 2 km has a significant influence on visual characteristics. In this range, with the increase in tunnel length, the maximum pupil diameter increases significantly, and the percentage of saccades increases rapidly. When the tunnel length exceeds 2 km, the maximum pupil diameter does not continue to increase. The longer the urban tunnel, the more discrete the distribution of drivers’ gaze points. The research results should provide a scientific basis for the design of urban tunnel traffic safety facilities and traffic organization.

Changes in pupillometry associated with dissipated energy during phacoemulsification

2020 ◽  
pp. 112067212098437
Author(s):  
Giulia Coco ◽  
Pierluca Cremonesi ◽  
Nardine Menassa ◽  
Luca Pagano ◽  
Kunal A Gadhvi ◽  
...  
Keyword(s):  
Cataract Surgery ◽  
Generalized Linear Model ◽  
Pupil Diameter ◽  
University Hospital ◽  
Dissipated Energy ◽  
Dynamic Measurements ◽  
Operative Complications ◽  
Cumulative Dissipated Energy ◽  
Chamber Measurements ◽  
Phacoemulsification Cataract Surgery

Purpose: To investigate the effect of ultrasound level during phacoemulsification on pupil dynamics. Methods: Comparative retrospective study on patients who underwent routine cataract surgery at the Royal Liverpool University Hospital. Clinical parameters, anterior chamber measurements, axial length, surgeon grade, time of surgery, level of ultrasound used (cumulative dissipated energy, CDE), intra- and post-operative complications were collected. Pupil diameters were collected before and 4 ± 1 weeks after surgery in static scotopic, mesopic, photopic pupil conditions. Also, pupil dynamic measurements after luminous stimulus were recorded. Changes in static pupil diameters, relative dilation at 3.5 s after luminous stimulus, and time to reach 75% and 95% of maximum dilation were measured. Results: Forty-eight eyes of 24 patients (13 males) were included with a mean age of 73.1 ± 14.6 years. Mean CDE value was 18.11 ± 10.56. Mean scotopic pupil diameters decreased by 0.24 ± 0.48 mm ( p = 0.021) in the operated eye. Significant correlation was found between reduction in scotopic pupil diameter and CDE ( p = 0.05). A generalized linear model confirmed that the level of CDE was significantly associated with reduction in scotopic pupil diameter ( p = 0.026). Patients who underwent surgeries with lower CDE (0 < CDE ⩽ 10 and 10 < CDE ⩽ 20) did not experience significant changes in scotopic pupil diameter after surgery ( p = 0.28 and p = 0.79, respectively) as opposed to those with higher CDE (CDE > 20; p = 0.03). Conclusion: Phacoemulsification cataract surgery and the cumulative dissipated energy may be associated with changes in pupil behaviour.

The Control of the Eye's Intrinsic Muscles: A Multivariable Optimum Performance Control System

1968 ◽  
Vol 1 (8) ◽  
pp. T.129-T.132 ◽  
Author(s):  
F. M. Toates
Keyword(s):  
Control System ◽  
Control Systems ◽  
Pupil Diameter ◽  
Control Model ◽  
Point Of View ◽  
Theoretical Point ◽  
Pupil Control ◽  
Performance Control ◽  
A Value ◽  
Intrinsic Muscles

The reciprocal interaction between the accommodation and pupil control systems of the human eye is examined from a theoretical point of view. The system, which is responsible for maintaining pupil diameter at a value which is a compromise between conflicting requirements, is represented by a control model, and is considered in terms of the concept of a performance index.

Directional effects of whole-body spinning and visual flow in virtual reality on vagal neuromodulation

2021 ◽  
pp. 1-16
Author(s):  
Alexander Yang Hui Xiang ◽  
Prashanna Khwaounjoo ◽  
Yusuf Ozgur Cakmak
Keyword(s):  
Heart Rate ◽  
Nervous System ◽  
Visual Stimulation ◽  
Pupil Diameter ◽  
Parasympathetic Activity ◽  
Whole Body ◽  
Vagal Activity ◽  
Eyes Closed ◽  
Visual Flow ◽  
Visual Interactions

BACKGROUND: Neural circuits allow whole-body yaw rotation to modulate vagal parasympathetic activity, which alters beat-to-beat variation in heart rate. The overall output of spinning direction, as well as vestibular-visual interactions on vagal activity still needs to be investigated. OBJECTIVE: This study investigated direction-dependent effects of visual and natural vestibular stimulation on two autonomic responses: heart rate variability (HRV) and pupil diameter. METHODS: Healthy human male subjects (n = 27) underwent constant whole-body yaw rotation with eyes open and closed in the clockwise (CW) and anticlockwise (ACW) directions, at 90°/s for two minutes. Subjects also viewed the same spinning environments on video in a VR headset. RESULTS: CW spinning significantly decreased parasympathetic vagal activity in all conditions (CW open p = 0.0048, CW closed p = 0.0151, CW VR p = 0.0019,), but not ACW spinning (ACW open p = 0.2068, ACW closed p = 0.7755, ACW VR p = 0.1775,) as indicated by an HRV metric, the root mean square of successive RR interval differences (RMSSD). There were no direction-dependent effects of constant spinning on sympathetic activity inferred through the HRV metrics, stress index (SI), sympathetic nervous system index (SNS index) and pupil diameter. Neuroplasticity in the CW eyes closed and CW VR conditions post stimulation was observed. CONCLUSIONS: Only one direction of yaw spinning, and visual flow caused vagal nerve neuromodulation and neuroplasticity, resulting in an inhibition of parasympathetic activity on the heart, to the same extent in either vestibular or visual stimulation. These results indicate that visual flow in VR can be used as a non-electrical method for vagus nerve inhibition without the need for body motion in the treatment of disorders with vagal overactivity. The findings are also important for VR and spinning chair based autonomic nervous system modulation protocols, and the effects of motion integrated VR.

A possible role of the norepinephrine system during sequential cognitive flexibility – Evidence from EEG and pupil diameter data

Cortex ◽  
2020 ◽  
Vol 128 ◽  
pp. 22-34 ◽  
Author(s):  
Franziska Giller ◽  
Moritz Mückschel ◽  
Tjalf Ziemssen ◽  
Christian Beste
Keyword(s):  
Cognitive Flexibility ◽  
Pupil Diameter ◽  
Norepinephrine System

scholarly journals Five-year changes in anterior segment parameters in an older population in urban southern China: the Liwan Eye Study

2019 ◽  
Vol 104 (4) ◽  
pp. 582-587 ◽  
Author(s):  
Yu Jiang ◽  
Decai Wang ◽  
Wei Wang ◽  
Feng Chen ◽  
Lanhua Wang ◽  
...  
Keyword(s):  
Anterior Chamber ◽  
Pupil Diameter ◽  
Southern China ◽  
Anterior Segment ◽  
Population Based ◽  
Light Conditions ◽  
Anterior Chamber Angle ◽  
The Mean ◽  
Angle Width

PurposeTo investigate the 5-year changes in static and dynamic anterior segment optical coherence tomography (AS-OCT) parameters and their predictors.MethodsThis was a prospective, population-based cohort study of people aged 50 years and older residing in the Liwan District, Guangzhou, China. Standardised AS-OCT scans were performed in November 2008 and November 2013 under dark and light conditions. Customised software was used to analyse horizontal AS-OCT images. Parameters in dark and measurements of light-to-dark changes were used for analyses.ResultsA total of 186 (71.8%) subjects underwent AS-OCT twice, 5 years apart and were included for analyses. The mean age in 2008 was 64.7±7.0 years, and 60.2% were women. The anterior chamber width (ACW) decreased from 11.74±0.44 mm in 2008 to 11.60±0.37 mm in 2013 (p=0.001). There was a trend towards a decrease in dynamic capacity (light-to-dark changes) in the anterior segment, with decreased iris thickness at 750 µm (ΔIT750), ΔACW, Δ anterior chamber area (ACA) and Δ pupil diameter at 5 years (all p<0.05). After adjusting for age and sex, the following baseline parameters were associated with a greater decrease rate in trabecular iris space area at 500 µm (TISA500) at 5 years: TISA500, IT750 and ACA in dark (p<0.001 for all).ConclusionsAnterior chamber angle width decreased and the amount of light-to-dark changes declined during 5-year follow-up. Subjects with greater height, wider angle width and thicker iris at baseline have greater angle narrowing at follow-up.

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