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Journal articles on the topic 'Change of pupil size'
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Kerr, Robert G., Andrea M. Bacon, Laura L. Baker, Janelle S. Gehrke, K. Danielle Hahn, Cheryl L. Lillegraven, Catherine Hackett Renner, and Sarah K. Spilman. "Underestimation of Pupil Size by Critical Care and Neurosurgical Nurses." American Journal of Critical Care 25, no. 3 (May 1, 2016): 213–19. http://dx.doi.org/10.4037/ajcc2016554.
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Background Early detection of pupillary changes in patients with head injuries can alert the care team to increasing intracranial pressure. Previous research has shown inconsistencies in pupil measurement that are most likely due to the subjective nature of measuring pupils without the assistance of technology. Objectives To evaluate nurses’ abilities to assess pupil diameter accurately and detect unequal pupils. Methods In a 3-part study, the accuracy of critical care and neurosurgical nurses’ assessments of pupils was determined. The study included assessment of drawings of eyes with an iris and pupil, examination of photographs of human eyes, and bedside examination of patients with a head injury. Results Subjective assessments of pupil diameter and symmetry were not accurate. Across all phases of the study, pupil diameters were underestimated and the rate of error increased as pupil size increased. Nurses also failed to detect anisocoria and misidentified pupil reactivity. In addition, nearly all nurses relied on subjective estimation, even when tools were available. Conclusions Critical care and neurosurgical nurses underestimated pupil size, were unable to detect anisocoria, and incorrectly assessed pupil reactivity. Standardized use of pupil assessment tools such as a pupillometer is necessary to increase accuracy and consistency in pupil measurement and to potentially contribute to earlier detection of subtle changes in pupils. If pupillary changes are identified early, diagnostic and treatment intervention can be delivered in a more timely and effective manner.
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Eberhardt, Lisa Valentina, Christoph Strauch, Tim Samuel Hartmann, and Anke Huckauf. "Increasing pupil size is associated with improved detection performance in the periphery." Attention, Perception, & Psychophysics 84, no. 1 (November 24, 2021): 138–49. http://dx.doi.org/10.3758/s13414-021-02388-w.
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AbstractVisible light enters our body via the pupil. By changing its size, the pupil shapes visual input. Small apertures increase the resolution of high spatial frequencies, thus allowing discrimination of fine details. Large apertures, in contrast, provide a better signal-to-noise ratio, because more light can enter the eye. This should lead to better detection performance of peripheral stimuli. Experiment 1 shows that the effect can reliably be demonstrated even in a less controlled online setting. In Experiment 2, pupil size was measured in a laboratory using an eye tracker. The findings replicate findings showing that large pupils provide an advantage for peripheral detection of faint stimuli. Moreover, not only pupil size during information intake in the current trial n, but also its interaction with pupil size preceding information intake, i.e., in trial n-1, predicted performance. This suggests that in addition to absolute pupil size, the extent of pupillary change provides a mechanism to modulate perceptual functions. The results are discussed in terms of low-level sensory as well as higher-level arousal-driven changes in stimulus processing.
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Van Egroo, Maxime, Giulia Gaggioni, Cristian Cespedes-Ortiz, Julien Q. M. Ly, and Gilles Vandewalle. "Steady-State Pupil Size Varies with Circadian Phase and Sleep Homeostasis in Healthy Young Men." Clocks & Sleep 1, no. 2 (May 10, 2019): 240–58. http://dx.doi.org/10.3390/clockssleep1020021.
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Pupil size informs about sympathovagal balance as well as cognitive and affective processes, and perception. It is also directly linked to phasic activity of the brainstem locus coeruleus, so that pupil measures have gained recent attention. Steady-state pupil size and its variability have been directly linked to sleep homeostasis and circadian phase, but results have been inconsistent. Here, we report robust changes in steady-state pupil size during 29 h of continuous wakefulness in healthy young men (N = 20; 18–30 years old) maintained in dim-light in strictly controlled constant routine conditions. These variations were associated with variations in motivation and sustained attention performance. Pupil size variability did not significantly change during the protocol. Yet, pupil size variability was linearly associated with subjective fatigue, sociability, and anguish. No associations were found between neither steady-state pupil size nor pupil size variability, and objective EEG measure of alertness and subjective sleepiness. Our data support therefore the notion that, compared with its variability, steady-state pupil size is strongly influenced by the concomitant changes in sleep need and circadian phase. In addition, steady-state pupil size appears to be related to motivation and attention, while its variability may be related to separate affective dimensions and subjective fatigue.
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Lau, Wee Kiat, Marian Sauter, and Anke Huckauf. "Small Pupils Lead to Lower Judgements of a Person’s Characteristics for Exaggerated, but Not for Realistic Pupils." Behavioral Sciences 12, no. 8 (August 12, 2022): 283. http://dx.doi.org/10.3390/bs12080283.
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Our eyes convey information about a person. The pupils may provide information regarding our emotional states when presented along with different emotional expressions. We examined the effects of pupil size and vergence on inferring other people’s characteristics in neutral expression eyes. Pupil sizes were manipulated by overlaying black disks onto the pupils of the original eye images. The disk area was then changed to create small, medium, and large pupils. Vergence was simulated by shifting the medium-sized disks nasally in one eye. Pupil sizes were exaggerated for Experiment 1 and followed values from the literature for Experiment 2. The first Purkinje image from the eye photos in Experiment 2 was kept to preserve image realism. The characteristics measured were sex, age, attractiveness, trustworthiness, intelligence, valence, and arousal. Participants completed one of two online experiments and rated eight eye pictures with differently sized pupils and with vergence eyes. Both experiments were identical except for the stimuli designs. Results from Experiment 1 revealed rating differences between pupil sizes for all characteristics except sex, age, and arousal. Specifically, eyes with extremely small pupil sizes and artificial vergence received the lowest ratings compared to medium and large pupil sizes. Results from Experiment 2 only indicated weak effects of pupil size and vergence, particularly for intelligence ratings. We conclude that the pupils can influence how characteristics of another person are perceived and may be regarded as important social signals in subconscious social interaction processes. However, the effects may be rather small for neutral expressions.
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Whang, Allen Jong-Woei, Yi-Yung Chen, Wei-Chieh Tseng, Chih-Hsien Tsai, Yi-Ping Chao, Chieh-Hung Yen, Chun-Hsiu Liu, and Xin Zhang. "Pupil Size Prediction Techniques Based on Convolution Neural Network." Sensors 21, no. 15 (July 21, 2021): 4965. http://dx.doi.org/10.3390/s21154965.
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The size of one’s pupil can indicate one’s physical condition and mental state. When we search related papers about AI and the pupil, most studies focused on eye-tracking. This paper proposes an algorithm that can calculate pupil size based on a convolution neural network (CNN). Usually, the shape of the pupil is not round, and 50% of pupils can be calculated using ellipses as the best fitting shapes. This paper uses the major and minor axes of an ellipse to represent the size of pupils and uses the two parameters as the output of the network. Regarding the input of the network, the dataset is in video format (continuous frames). Taking each frame from the videos and using these to train the CNN model may cause overfitting since the images are too similar. This study used data augmentation and calculated the structural similarity to ensure that the images had a certain degree of difference to avoid this problem. For optimizing the network structure, this study compared the mean error with changes in the depth of the network and the field of view (FOV) of the convolution filter. The result shows that both deepening the network and widening the FOV of the convolution filter can reduce the mean error. According to the results, the mean error of the pupil length is 5.437% and the pupil area is 10.57%. It can operate in low-cost mobile embedded systems at 35 frames per second, demonstrating that low-cost designs can be used for pupil size prediction.
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Kim, Jieun, Jeong-Chan Lee, and Kyung-Mo Park. "Posture change affects pupil size — Males in their twenties." Autonomic Neuroscience 135, no. 1-2 (September 2007): 133–34. http://dx.doi.org/10.1016/j.autneu.2007.06.232.
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Mattavelli, Simone, Marco Brambilla, and Mariska E. Kret. "It Is Written in the Eyes: Inferences From Pupil Size and Gaze Orientation Shape Interpersonal Liking." Social Cognition 40, no. 1 (February 2022): 88–106. http://dx.doi.org/10.1521/soco.2022.40.1.88.
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Research has shown that pupil size shapes interpersonal impressions: Individuals with dilated pupils tend to be perceived more positively than those with constricted pupils. Untested so far is the role of cognitive processes in shaping the effects of pupil size. Two preregistered studies investigated whether the effect of pupil size was qualified by partner's attention allocation inferred from gaze orientation. In Experiment 1 (N = 50) partners with dilated pupils were more liked when gazing toward the participant, but less liked when gazing toward a disliked other. Experiment 2 (N = 50) unveiled the underlying mechanism of the pupil-gaze interplay. Pupillary changes led to inferences about the feelings held by the partner toward the gazed target: Larger pupils signaled positive feelings. Crucially, target identity moderated the response of the participants (i.e., liking toward the partner). This work shows the importance of considering the interplay of affective and cognitive eye-signals when studying person perception.
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Zhang, Jing, Sung Park, Ayoung Cho, and Mincheol Whang. "Significant Measures of Gaze and Pupil Movement for Evaluating Empathy between Viewers and Digital Content." Sensors 22, no. 5 (February 22, 2022): 1700. http://dx.doi.org/10.3390/s22051700.
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The success of digital content depends largely on whether viewers empathize with stories and narratives. Researchers have investigated the elements that may elicit empathy from viewers. Empathic response involves affective and cognitive processes and is expressed through multiple verbal and nonverbal modalities. Specifically, eye movements communicate emotions and intentions and may reflect an empathic status. This study explores feature changes in eye movements when a viewer empathizes with the video’s content. Seven feature variables of eye movements (change of pupil diameter, peak pupil dilation, very short, mid, over long fixation duration, saccadic amplitude, and saccadic count) were extracted from 47 participants who viewed eight videos (four empathic videos and four non-empathic videos) distributed in a two-dimensional emotion axis (arousal and valence). The results showed that viewers’ saccadic amplitude and peak pupil dilation in the eigenvalues of eye movements increased in the empathic condition. The fixation time and pupil size change showed limited significance, and whether there were asymmetric pupil responses between the left and right pupils remained inconclusive. Our investigation suggests that saccadic amplitude and peak pupil dilation are reliable measures for recognizing whether viewers empathize with content. The findings provide physiological evidence based on eye movements that both affective and cognitive processes accompany empathy during media consumption.
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Schriver, Brian J., Svetlana Bagdasarov, and Qi Wang. "Pupil-linked arousal modulates behavior in rats performing a whisker deflection direction discrimination task." Journal of Neurophysiology 120, no. 4 (October 1, 2018): 1655–70. http://dx.doi.org/10.1152/jn.00290.2018.
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Non-luminance-mediated changes in pupil size have been widely used to index arousal state. Recent animal studies have demonstrated correlations between behavioral state-related pupil dynamics and sensory processing. However, the relationship between pupil-linked arousal and behavior in animals performing perceptual tasks has not been fully elucidated. In the present study, we trained head-fixed rats to discriminate between directions of whisker movements using a Go/No-Go discrimination paradigm while imaging their pupils. Reaction times in this discrimination task were significantly slower than in previously reported detection tasks with similar setup, suggesting that discrimination required an increased cognitive load. We found the pupils dilated for all trials following stimulus presentation. Interestingly, in correct rejection trials, where pupil dilations solely resulted from cognitive processing, dilations were larger for more difficult stimuli. Baseline pupil size before stimulus presentation strongly correlated with behavior, as perceptual sensitivity peaked at intermediate pupil baselines and reaction time was fastest at large baselines. We further explored these relationships by investigating to what extent pupil baseline was predictive of upcoming behavior and found that a Bayesian decoder had significantly greater-than-chance probability in correctly predicting behavioral outcomes. Moreover, the outcome of the previous trial showed a strong correlation with behavior on present trials. Animals were more liberal and faster in responding following hit trials, whereas perceptual sensitivity was greatest following correct rejection trials. Taken together, these results suggest a tight correlation between pupil dynamics, perceptual performance, and reaction time in behaving rats, all of which are modulated by fluctuating arousal state. NEW & NOTEWORTHY In this study, we for the first time demonstrated that head-fixed rats were able to discriminate different directions of whisker movement. Interestingly, we found that the pupil dilated more when discriminating more difficult stimuli, a phenomenon reported in human subjects but not in animals. Baseline pupil size before stimulus presentation was found to strongly correlate with behavior, and a Bayesian decoder had significantly greater-than-chance probability in correctly predicting behavioral outcomes based on the baseline pupil size.
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Tyukhova, Y., and CE Waters. "Subjective and pupil responses to discomfort glare from small, high-luminance light sources." Lighting Research & Technology 51, no. 4 (June 6, 2018): 592–611. http://dx.doi.org/10.1177/1477153518772000.
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This study examined human subjective and pupil responses to small, high-luminance light sources seen against low-luminance backgrounds. Subjective judgements of glare using a seven-point rating scale and the change in pupil diameters following exposure to glare of 47 subjects were measured during evaluation of 36 conditions comprising three glare source luminances (20,000; 205,000; 750,000 cd/m2), two source positions (0°, 10°), two source sizes (10−5, 10−4 sr) and three background luminances (0.03; 0.3; 1 cd/m2). Data analysis suggests that the relative pupil size is correlated with subjective responses to discomfort glare to some extent (r = 0.659). Analysis of variance of relative pupil size measurements demonstrates a significant main effect of the background luminance suggesting that when the background luminance decreases, the relative pupil size increases. Relative pupil size shows the same trend as the relative change in illuminance at the eyes and the discomfort glare perception.
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Pronk, Tila M., Rebecca I. Bogaers, Mara S. Verheijen, and Willem W. A. Sleegers. "Pupil Size Predicts Partner Choices in Online Dating." Social Cognition 39, no. 6 (December 2021): 773–86. http://dx.doi.org/10.1521/soco.2021.39.6.773.
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People's choices for specific romantic partners can have far reaching consequences, but very little is known about the process of partner selection. In the current study, we tested whether a measure of physiological arousal, pupillometry (i.e., changes in pupil size), can predict partner choices in an online dating setting. A total of 239 heterosexual participants took part in an online dating task in which they accepted or rejected hypothetical potential partners, while pupil size response was registered using an eye tracker. In line with our main hypothesis, the results indicated a positive association between pupil size and partner acceptance. This association was not found to depend on relationship status, relationship quality, gender, or sociosexual orientation. These findings show that the body (i.e., the pupils) provides an automatic cue of whether a potential partner will be selected as a mate, or rejected.
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WILSON, M. ANNE, MELANIE C. W. CAMPBELL, and PIERRE SIMONET. "The Julius F. Neumueller Award in Optics, 1989: Change of Pupil Centration with Change of Illumination and Pupil Size." Optometry and Vision Science 69, no. 2 (February 1992): 129–36. http://dx.doi.org/10.1097/00006324-199202000-00006.
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Yu, Hanyang, Wentao Li, Ziping Chen, Mengzhen Chen, Junwen Zeng, Xijiang Lin, and Feng Zhao. "Is Ocular Accommodation Influenced by Dynamic Ambient Illumination and Pupil Size?" International Journal of Environmental Research and Public Health 19, no. 17 (August 23, 2022): 10490. http://dx.doi.org/10.3390/ijerph191710490.
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Purpose: We investigated ocular accommodative responses and pupil diameters under different light intensities in order to explore whether changes in light intensity aid effective accommodation function training. Methods:A total of 29 emmetropic and myopic subjects (age range: 12–18 years) viewed a target in dynamic ambient light (luminance: 5, 100, 200, 500, 1000, 2000 and 3000 lux) and static ambient light (luminance: 1000 lux) at a 40 cm distance with refractive correction. Accommodation and pupil diameter were recorded using an open-field infrared autorefractor and an ultrasound biological microscope, respectively. Results: The changes in the amplitude of accommodative response and pupil diameter under dynamic lighting were 1.01 ± 0.53 D and 2.80 ± 0.75 mm, respectively, whereas in static lighting, those values were 0.43 ± 0.24 D and 0.77 ± 0.27 mm, respectively. The amplitude of accommodation and pupil diameter change in dynamic lighting (t = 6.097, p < 0.001) was significantly larger than that under static lighting (t = 16.115, p < 0.001).The effects of light level on both accommodation and pupil diameter were significant (p < 0.001). Conclusion: Accommodation was positively correlated with light intensity. The difference was about 1.0 D in the range of 0–3000 lux, which may lay the foundation for accommodative training through light intervention.
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Yamamoto, Hiromi, and Yasutaka Shimizu. "Change of pupil size and blinking time in memorizing numerals." Journal of the Institute of Television Engineers of Japan 45, no. 3 (1991): 370–76. http://dx.doi.org/10.3169/itej1978.45.370.
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Otero, Samantha C., Brendan S. Weekes, and Samuel B. Hutton. "Pupil size changes during recognition memory." Psychophysiology 48, no. 10 (May 16, 2011): 1346–53. http://dx.doi.org/10.1111/j.1469-8986.2011.01217.x.
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Binda, Paola, Maria Pereverzeva, and Scott O. Murray. "Pupil size reflects the focus of feature-based attention." Journal of Neurophysiology 112, no. 12 (December 15, 2014): 3046–52. http://dx.doi.org/10.1152/jn.00502.2014.
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We measured pupil size in adult human subjects while they selectively attended to one of two surfaces, bright and dark, defined by coherently moving dots. The two surfaces were presented at the same location; therefore, subjects could select the cued surface only on the basis of its features. With no luminance change in the stimulus, we find that pupil size was smaller when the bright surface was attended and larger when the dark surface was attended: an effect of feature-based (or surface-based) attention. With the same surfaces at nonoverlapping locations, we find a similar effect of spatial attention. The pupil size modulation cannot be accounted for by differences in eye position and by other variables known to affect pupil size such as task difficulty, accommodation, or the mere anticipation (imagery) of bright/dark stimuli. We conclude that pupil size reflects not just luminance or cognitive state, but the interaction between the two: it reflects which luminance level in the visual scene is relevant for the task at hand.
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Larson, Merlin D., Farzin Tayefeh, Daniel I. Sessler, Malcolm Daniel, and Mimi Noorani. "Sympathetic Nervous System Does Not Mediate Reflex Pupillary Dilation during Desflurane Anesthesia." Anesthesiology 85, no. 4 (October 1, 1996): 748–54. http://dx.doi.org/10.1097/00000542-199610000-00009.
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Background Pupil size is determined by an interaction between the sympathetic and parasympathetic divisions of the autonomic nervous system. Noxious stimulation dilates the pupil in both unanesthetized and anesthetized humans. In the absence of anesthesia, dilation is primarily mediated by the sympathetic nervous system. In contrast, pupillary dilation in cats given barbiturate or cloralose anesthesia is mediated solely by inhibition of the midbrain parasympathetic nucleus. The mechanism by which noxious stimuli dilate pupils during anesthesia in humans remains unknown. Accordingly, the authors tested the hypothesis that the pupillary dilation in response to noxious stimulation during desflurane anesthesia is primarily a parasympathetic reflex. Methods In six volunteers, the alpha-I adrenergic receptors of the iris musculature were blocked by unilateral administration of topical dapiprazole; six other volunteers were given unilateral topical tropicamide to block the muscarinic receptors in the iris. Desflurane anesthesia was subsequently induced in all volunteers. Sympathetic nervous system activation, with reflex dilation of the pupil, was produced by noxious electrical stimulation during 4% and 8% end-tidal desflurane, and by a rapid 4%-to-8% step-up in the desflurane concentration. Pupil diameter and the change in pupil size induced by a light stimulus (light reflex amplitude) were measured with infrared pupillometry. Results Dapiprazole drops produced a Horner's miosis, but pupils were equally small after induction of anesthesia. Pupillary dilation after noxious stimulation and desflurane step-up was identical in the unblocked and dapiprazole-blocked pupils. After tropicamide administration, the pupil was dilated and the light reflex was completely inhibited. Noxious stimulation nonetheless produced a slight additional dilation. Conclusions During desflurane anesthesia, pupillary dilation in response to noxious stimulation or desflurane step-up is not mediated by the sympathetic nervous system (as it is in unanesthetized persons). Although inhibition of the pupillo-constrictor nucleus may be the cause of this dilation, the mechanism remains unknown.
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Sołek-Pastuszka, Joanna, Małgorzata Zegan-Barańska, Jowita Biernawska, Marcin Sawicki, Waldemar Iwańczuk, Kornel Chełstowski, Romuald Bohatyrewicz, Wojciech Dąbrowski, and Klaudyna Kojder. "Atypical Pupil Reactions in Brain Dead Patients." Brain Sciences 11, no. 9 (September 10, 2021): 1194. http://dx.doi.org/10.3390/brainsci11091194.
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Background: During routine diagnosis of brain death, changes in pupil diameter in response to the stimulation of peripheral nerves are sometimes observed. For example, pupillary dilation after diagnosed brain death is described in the literature as the ciliospinal reflex. However, pupil constriction creates diagnostic doubts. Objective: The pupillometric analysis of pupil response to stimulation of the cervicothoracic spinal cord in patients with diagnosed brain death. Methods: Instrumental tests to confirm the arrest of cerebral circulation were performed in 30 adult subjects (mean age 53.5 years, range 26–75 years) with diagnosed brain death. In addition, a pupillometer was used to measure the change in pupil diameter in response to neck flexion. Intervention: Flexion of the neck and measuring the response in change of the pupil with the use of the pupillometer. Results: The change in the pupil was observed in the examined group of patients. Difference in pupil size ≥ 0.2 mm was observed in 14 cases (46%). In five cases (17%), pupil constriction was found (from 0.2 to 0.7 mm). Measurement error was +/− 0.1 mm. Conclusions: Both pupillary constriction and dilatation may occur due to a ciliospinal reflex in patients with brain death. This phenomenon needs further research in order to establish its pathophysiology.
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QIAN, Chencan, and Zuxiang LIU. "Pupil size is sensitive to dynamic change in scene layout properties." Journal of Vision 17, no. 10 (August 31, 2017): 566. http://dx.doi.org/10.1167/17.10.566.
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Binda, Paola, and Claudia Lunghi. "Short-Term Monocular Deprivation Enhances Physiological Pupillary Oscillations." Neural Plasticity 2017 (2017): 1–10. http://dx.doi.org/10.1155/2017/6724631.
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Short-term monocular deprivation alters visual perception in adult humans, increasing the dominance of the deprived eye, for example, as measured with binocular rivalry. This form of plasticity may depend upon the inhibition/excitation balance in the visual cortex. Recent work suggests that cortical excitability is reliably tracked by dilations and constrictions of the pupils of the eyes. Here, we ask whether monocular deprivation produces a systematic change of pupil behavior, as measured at rest, that is independent of the change of visual perception. During periods of minimal sensory stimulation (in the dark) and task requirements (minimizing body and gaze movements), slow pupil oscillations, “hippus,” spontaneously appear. We find that hippus amplitude increases after monocular deprivation, with larger hippus changes in participants showing larger ocular dominance changes (measured by binocular rivalry). This tight correlation suggests that a single latent variable explains both the change of ocular dominance and hippus. We speculate that the neurotransmitter norepinephrine may be implicated in this phenomenon, given its important role in both plasticity and pupil control. On the practical side, our results indicate that measuring the pupil hippus (a simple and short procedure) provides a sensitive index of the change of ocular dominance induced by short-term monocular deprivation, hence a proxy for plasticity.
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Sulutvedt, Unni, Daniele Zavagno, Jamie Lubell, Siri Leknes, Sigrid A. de Rodez Benavent, and Bruno Laeng. "Brightness perception changes related to pupil size." Vision Research 178 (January 2021): 41–47. http://dx.doi.org/10.1016/j.visres.2020.09.004.
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Miyao, Masaru, Shin'Ya Ishihara, Hisao Ishigaki, Tomonori Sugiura, Eiji Matsuura, Masashi Furuta, and Toshihiro Sakata. "Psychology of Computer Use: XXX. Effects of Presentation Speed on Pupil Size Using Negative and Positive Crts." Perceptual and Motor Skills 77, no. 3 (December 1993): 979–84. http://dx.doi.org/10.2466/pms.1993.77.3.979.
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The effects of presentation speed and both positive and negative CRT (cathode ray tube) displays on pupil size were studied. The pupillary areas of 12 female student volunteers were measured by infrared videopupillography. The three presentation speeds were no change for 12 sec., a change every 2 sec. for 12 sec., and a change every 1/2 sec. for 12 sec. Two-way analysis of variance showed that the pupil size in the negative displays was significantly larger than that in the positive displays. A difference in pupillary area results from different display speeds, irrespective of a difference in polarity.
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Benitez, Viridiana L., and Matthew K. Robison. "Pupillometry as a Window into Young Children’s Sustained Attention." Journal of Intelligence 10, no. 4 (November 16, 2022): 107. http://dx.doi.org/10.3390/jintelligence10040107.
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Sustained attention is critical to cognition, social competence, and academic success. Importantly, sustained attention undergoes significant development over the early childhood period. Yet, how sustained attention fluctuates over time on task has not been clearly outlined, particularly in young children. In this study, we provide a first test of whether the pupillary response can be used as an indicator of moment-to-moment sustained attention over time on task in young children. Children aged 5 to 7 years (N = 41) completed a psychomotor vigilance task, where they were asked to press a button as fast as possible at the onset of a target stimulus. We measured reaction times over the course of the task, pupil size prior to target onset (baseline pupil size), and pupil size in response to target onset (task-evoked pupil size). The results showed a stereotypical vigilance decrement in children’s response times: as time on task increased, reaction times increased. Critically, children’s task-evoked pupil size decreased over time on task, while no such change was present in baseline pupil size. These results suggest that young children’s waning sustained attention may be linked to a decrease in alertness while overall arousal is maintained. We discuss the importance of leveraging pupillometry to understand the mechanisms of sustained attention over individuals and development.
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Bardak, Handan, Murat Gunay, Ugur Mumcu, and Yavuz Bardak. "Effect of Single Administration of Coffee on Pupil Size and Ocular Wavefront Aberration Measurements in Healthy Subjects." BioMed Research International 2016 (2016): 1–5. http://dx.doi.org/10.1155/2016/9578308.
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No study has so far evaluated the impact of coffee drinking on ocular wavefront aberration (OWA) measurements. This study presents novel findings regarding the OWA of the eye following coffee intake. We aimed to evaluate the acute changes in pupil size and OWA of the eye after single administration of coffee. A total of 30 otherwise healthy participants were included in this prospective study. All subjects drank a cup of coffee containing 57 mg caffeine. Measurements of pupil size, total coma (TC), total trefoil (TF), total spherical aberration (TSA), and total higher order aberration (HOA) were performed before and at 5 minutes, at 30 minutes, and at 4 hours after coffee drinking using a wavefront aberrometer device (Irx3, Imagine Eyes, Orsay, France). The mean age of the study population was 20.30 ± 2.74 years. Pupil size did not show a significant change during the measurements (p>0.05). A significant increase was observed in TF and HOA measurements following coffee intake (p=0.029andp=0.009, resp.). Single administration of coffee results in significant increase in TF and total HOAs in healthy subjects without any effect on pupil diameter. Ultrastructural changes in the cornea following coffee intake might be of relevance to the alterations in ocular aberrations in healthy subjects.
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Fonseca, Elsa, Paulo Fiadeiro, Renato Gomes, Angel Sanchez Trancon, António Baptista, and Pedro Serra. "Pupil Function in Pseudophakia: Proximal Miosis Behavior and Optical Influence." Photonics 6, no. 4 (November 6, 2019): 114. http://dx.doi.org/10.3390/photonics6040114.
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The pseudophakic eye lacks the ability to produce a refractive change in response to object proximity. Thus, individual anatomical features such as the pupil size play an important role in achieving functional vision levels. In this work, the range of pupil sizes at varying object distance was measured in pseudophakic participants. Furthermore, the impact of the measured values on eye optical quality was investigated using a computer simulation model. A binocular eye-tracker was used to measure the participants’ pupil sizes at six object distances, ranging from 0.33 m (i.e., vergence of 3.00 D) to 3.00 m (i.e., vergence of 0.33 D), while observing a Maltese cross with a constant angular size of 1 ∘ . In total, 58 pseudophakic participants were enrolled in this study (age mean ± standard deviation: 70.5 ± 11.3 years). The effects of object distance and age on pupil size variation were investigated using linear mixed effects regression models. Age was found to have a small contribution to individual variability. The mean infinite distance pupil size (intercept) was 4.45 ( 95 % CI: 2.74, 6.17) mm and the mean proximal miosis (slope) was − 0.23 ( 95 % CI: −0.53, 0.08) mm/D. The visual acuity (VA) estimation for a distant object ranged from − 0.1 logMAR (smallest pupil) to 0.04 logMAR (largest pupil) and the near VA ( 0.33 m) when mean proximal miosis was considered ranged from 0.28 logMAR (smallest pupil) to 0.42 logMAR (largest pupil). When mean distance pupil was considered, proximal miosis individual variability produced a variation of 0.04 logMAR for the near object and negligible variation for the distant object. These results support the importance of distance pupil size measurement for the prediction of visual performance in pseudophakia, while suggesting that proximal miosis has a negligible impact in VA variability.
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Vardar, Tonguç, and Fatih Senduran. "The cognitive workload of air pistol shooters on the aiming task." Pakistan Journal of Medical and Health Sciences 15, no. 9 (September 30, 2021): 2610–15. http://dx.doi.org/10.53350/pjmhs211592610.
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Background: Pupil dilations of the eye are known to correspond to central cognitive processes. Pupil size variations have been used for many years as a window on the mind, and various pupillary features have been associated with a number of cognitive processes Aim: The aim of this study is to examine levels of cognitive workload that occur during the aiming task of air-pistol shooting athletes according to the change that takes place in the pupils. Methods: Eight right-handed skilled male shooters (4 elite and 4 novice) were recruited in this study. A total of 320 shots - 160 dry (unscored) shots and 160 live (scored) shots - were recorded with a mobile eye-tracking device. The obtained pupil data were subjected to biometric analysis. The athletes’ pupil sizes were determined with the independent samples t-test according to whether the shot made was scored or unscored and whether the athletes were elite or novice. The athletes’ pupil size values at the beginning and end of the shot were obtained using the paired samples t-test. Results: On completion of the shot, the sport shooters’ pupils dilated on average by 2.85 mm at a rate of 32.5% compared to the situation at shot onset. Moreover, novice shooters’ pupils dilated more when firing scored shots than when firing unscored shots. According to the research results, it can be said that sports shooters engage in intensive cognitive processes while aiming and trigger pulling immediately before firing the shot. Novice shooters engage in more intensive cognitive processes when firing scored shots than when firing unscored shots. Conclusion: According to the results of the research, it can be said that in the sport of air pistol shooting, giving priority to dry (unscored) shooting training can contribute positively to the development of novice athletes’ aiming task skills and cognitive load capacity. Keywords: Cognitive workload, cognitive processes, eye tracking, air pistol, shooting
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Dhallu, Sheppard, Drew, Mihashi, Zapata-Díaz, Radhakrishnan, Iskander, and Wolffsohn. "Factors Influencing Pseudo-Accommodation—The Difference between Subjectively Reported Range of Clear Focus and Objectively Measured Accommodation Range." Vision 3, no. 3 (June 28, 2019): 34. http://dx.doi.org/10.3390/vision3030034.
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The key determinants of the range of clear focus in pre-presbyopes and their relative contributions to the difference between subjective range of focus and objective accommodation assessments have not been previously quantified. Fifty participants (aged 33.0 ± 6.4 years) underwent simultaneous monocular subjective (visual acuity measured with an electronic test-chart) and objective (dynamic accommodation measured with an Aston open-field aberrometer) defocus curve testing for lenses between +2.00 to -10.00 DS in +0.50 DS steps in a randomized order. Pupil diameter and ocular aberrations (converted to visual metrics normalized for pupil size) at each level of blur were measured. The difference between objective range over which the power of the crystalline lens changes and the subjective range of clear focus was quantified and the results modelled using pupil size, refractive error, tolerance to blur, and ocular aberrations. The subjective range of clear focus was principally accounted for by age (46.4%) and pupil size (19.3%). The objectively assessed accommodative range was also principally accounted for by age (27.6%) and pupil size (15.4%). Over one-quarter (26.0%) of the difference between objective accommodation and subjective range of clear focus was accounted for by age (14.0%) and spherical aberration at maximum accommodation (12.0%). There was no significant change in the objective accommodative response (F=1.426, p=0.229) or pupil size (F=0.799, p=0.554) of participants for levels of defocus above their amplitude of accommodation. Pre-presbyopes benefit from an increased subjective range of clear vision beyond their objective accommodation due in part to neural factors, resulting in a measured depth-of-focus of, on average, 1.0D.
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Ferencová, N., Z. Višňovcová, L. Bona Olexová, and I. Tonhajzerová. "Eye pupil – a window into central autonomic regulation via emotional/cognitive processing." Physiological Research, S4 (December 30, 2021): S669—S682. http://dx.doi.org/10.33549//physiolres.934749.
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If the eyes are windows into the soul, then the pupils represent at least the gateway to the brain and can provide a unique insight into the human mind from several aspects. The changes in the pupil size primarily mediated by different lighting conditions are controlled by the autonomic nervous system regulated predominantly at the subcortical level. Specifically, parasympathetically-linked pupillary constriction is under the Edinger-Westphal nucleus control and sympathetically-mediated pupillary dilation is regulated from the posterior hypothalamic nuclei. However, the changes in the pupil size can be observed at resting state even under constant lighting, these pupillary changes are mediated by global arousal level as well as by various cognitive factors. In this context, autonomic pathways modulating changes in the pupil size in response to the different light levels can be influenced by multiple central descending inputs driving pupillary changes under steady lighting conditions. Moreover, as the pupillary response is involved in emotional (task-evoked pupillary dilation as an index of emotional arousal) and cognitive (task-evoked pupillary dilation as an index of cognitive workload) stimulation, it can be used to detect the impact of mutual subcortical and cortical structures (i.e. overlapping brain structures included in autonomic, emotional and cognitive regulation) on the pupillary innervation system. Thus, complex understanding of the baseline pupil size´ and pupillary dynamics´ mechanisms may provide an important insight into the central nervous system functioning pointing to the pupillometry as a promising tool in the clinical application.
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Lee, Poh Foong, and Khai Shan Lee. "A PRELIMINARY STUDY ON PUPIL SIZE CHANGES DETECTION ON MENTAL STRESS WITH MENTAL STRESSOR." Biomedical Engineering: Applications, Basis and Communications 29, no. 02 (April 2017): 1750011. http://dx.doi.org/10.4015/s1016237217500119.
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This is a study on measuring the effect of stress that stimulated by the different difficulty of game level on pupil dilation. Playing games are claimed a method to distress in the community, however, this activity is enhancing stress level? The effect of the game playing on the changes of pupil dilation is unknown. An investigation was conducted on relating the changes of pupil diameter measurement at the different difficulty levels of the game. A simple tool was developed by using a webcam as image acquisition device together with MATLAB Image Processing Tool to analyze the acquired images. Here, experiments on the pupil detection algorithm, which consisted of four different methods are to work alternatively with one another and to provide higher chances of pupil detection. 10 subjects were involved in the experiments, which they were requested to play a selected game with four different ascending increased in difficulties, meanwhile, pupil size changes were measured simultaneously. The selected game served as a stress stimulus to the subjects. The result showed a positive proportional relationship between increased in game difficulty levels and pupil dilation. The investigation reported that the pupil dilated when the difficulty of game level increased. Limitation of this study is the sample size on the prototype testing should be increased to concrete the outcome.
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Fotiou, Dimitris F., Catherine G. Brozou, Anna-Bettina Haidich, Dimitris Tsiptsios, Maria Nakou, Anastasia Kabitsi, Charalambos Giantselidis, and Fotis Fotiou. "Pupil reaction to light in Alzheimer’s disease: evaluation of pupil size changes and mobility." Aging Clinical and Experimental Research 19, no. 5 (October 2007): 364–71. http://dx.doi.org/10.1007/bf03324716.
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Franzen, Léon, Amanda Cabugao, Bianca Grohmann, Karine Elalouf, and Aaron P. Johnson. "Individual pupil size changes as a robust indicator of cognitive familiarity differences." PLOS ONE 17, no. 1 (January 21, 2022): e0262753. http://dx.doi.org/10.1371/journal.pone.0262753.
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Cognitive psychology has a long history of using physiological measures, such as pupillometry. However, their susceptibility to confounds introduced by stimulus properties, such as color and luminance, has limited their application. Pupil size measurements, in particular, require sophisticated experimental designs to dissociate relatively small changes in pupil diameter due to cognitive responses from larger ones elicited by changes in stimulus properties or the experimental environment. Here, building on previous research, we present a pupillometry paradigm that adapts the pupil to stimulus properties during the baseline period without revealing stimulus meaning or context by using a pixel-scrambled image mask around an intact image. We demonstrate its robustness in the context of pupillary responses to branded product familiarity. Results show larger average and peak pupil dilation for passively viewed familiar product images and an extended later temporal component representing differences in familiarity across participants (starting around 1400 ms post-stimulus onset). These amplitude differences are present for almost all participants at the single-participant level, and vary somewhat by product category. However, amplitude differences were absent during the baseline period. These findings demonstrate that involuntary pupil size measurements combined with the presented paradigm are successful in dissociating cognitive effects of familiarity from physical stimulus confounds.
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WU, Ling, Weihua ZHAO, Tong ZHU, and Haoxue LIU. "Drivers in Expressway Superlong Tunnels: The Change Patterns of Visual Features and the Discriminant Model of Driving Safety." Journal of Asian Research 3, no. 3 (August 19, 2019): p240. http://dx.doi.org/10.22158/jar.v3n3p240.
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A real-vehicle experiment was carried out in the superlong highway tunnel environment to study the change patterns of driver’s visual features, tracked by eye tracking devices, and the discriminant model of driver’s safety status. On the basis of statistical analysis, a single index and a comprehensive index discriminant model, both based on a C4.5 decision tree, were established. The results showed that compared with the non-tunnel highway sections, the driver’s pupil size was larger, and the gaze duration was longer in the tunnel section. Driver’s pupil size was larger in mid-tunnel section than in the entrance section and exit section. Gazes at the exit section were mainly short gazes. Compared to the exit section, driver’s pupil size changed more dramatically in the entrance section, and the gaze duration was longer. The single visual parameter indicator could clearly discriminate the driver’s safety status in the mid-tunnel section and the non-tunnel sections, while the dual-index-based identification model could clearly discriminate the safety status in each highway sections. The study deepens the research on the driver information perception model in superlong highway tunnels. Also, the study provides a theoretical basis for establishing a visual-feature-based real-time safety status discriminant.
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Kalmár, György, Alexandra Büki, Gabriella Kékesi, Gyöngyi Horváth, and László G. Nyúl. "Image Processing-based Automatic Pupillometry on Infrared Videos." Acta Cybernetica 23, no. 2 (2017): 599–613. http://dx.doi.org/10.14232/actacyb.23.2.2017.10.
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Pupillometry is a non-invasive technique that can be used to objectively characterize pathophysiological changes involving the pupillary reflex. It is essentially the measurement of the pupil diameter over time. Here, specially designed computer algorithms provide fast, reliable and reproducible solutions for the analysis. These methods use a priori information about the shape and color of the pupil. Our study focuses on measuring the diameter and dynamics of the pupils of rats with schizophrenia using videos recorded with a modified digital camera under infrared (IR) illumination. We developed a novel, robust method that measures the size of a pupil even under poor circumstances (noise, blur, reflections and occlusions). We compare our results with measurements obtained using manual annotation.
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Schwartz, Zachary P., Brad N. Buran, and Stephen V. David. "Pupil-associated states modulate excitability but not stimulus selectivity in primary auditory cortex." Journal of Neurophysiology 123, no. 1 (January 1, 2020): 191–208. http://dx.doi.org/10.1152/jn.00595.2019.
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Recent research in mice indicates that luminance-independent fluctuations in pupil size predict variability in spontaneous and evoked activity of single neurons in auditory and visual cortex. These findings suggest that pupil is an indicator of large-scale changes in arousal state that affect sensory processing. However, it is not known whether pupil-related state also influences the selectivity of auditory neurons. We recorded pupil size and single-unit spiking activity in the primary auditory cortex (A1) of nonanesthetized male and female ferrets during presentation of natural vocalizations and tone stimuli that allow measurement of frequency and level tuning. Neurons showed a systematic increase in both spontaneous and sound-evoked activity when pupil was large, as well as desynchronization and a decrease in trial-to-trial variability. Relationships between pupil size and firing rate were nonmonotonic in some cells. In most neurons, several measurements of tuning, including acoustic threshold, spectral bandwidth, and best frequency, remained stable across large changes in pupil size. Across the population, however, there was a small but significant decrease in acoustic threshold when pupil was dilated. In some recordings, we observed rapid, saccade-like eye movements during sustained pupil constriction, which may indicate sleep. Including the presence of this state as a separate variable in a regression model of neural variability accounted for some, but not all, of the variability and nonmonotonicity associated with changes in pupil size. NEW & NOTEWORTHY Cortical neurons vary in their response to repeated stimuli, and some portion of the variability is due to fluctuations in network state. By simultaneously recording pupil and single-neuron activity in auditory cortex of ferrets, we provide new evidence that network state affects the excitability of auditory neurons, but not sensory selectivity. In addition, we report the occurrence of possible sleep states, adding to evidence that pupil provides an index of both sleep and physiological arousal.
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Mirshahi, Alireza, Astrid Schneider, Catharina Latz, and Katharina A. Ponto. "Perioperative pupil size in low-energy femtosecond laser-assisted cataract surgery." PLOS ONE 16, no. 5 (May 17, 2021): e0251549. http://dx.doi.org/10.1371/journal.pone.0251549.
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Purpose To assess potential changes in pupil size during femtosecond laser-assisted cataract surgery (FLACS) using a low-energy laser system. Methods The pupil sizes of eyes undergoing FLACS were measured using the Ziemer LDV Z8 by extracting images from the laser software after each of the following steps: application of suction, lens fragmentation, and capsulotomy. Furthermore, the pupil diameters were measured based on preoperative surgical microscope images and after releasing the suction. Paired t-test and the two one-sided tests (TOST) procedure were used for statistical analyses. The horizontal and vertical pupil diameters were compared in each of the steps with preoperative values. Results Data were available for 52 eyes (52 patients, mean age 73.4 years, range 51–87 years). The equivalence between mean preoperative pupil size and status immediately after femtosecond laser treatment was confirmed (p<0.001; 95% confidence interval [−0.0637, 0.0287] for horizontal and p<0.001; 95% CI [−0.0158, 0.0859] for vertical diameter). There was statistically significant horizontal and vertical enlargement of pupil diameters between 0.15 and 0.24 mm during the laser treatment steps as compared with preoperative values (all p values <0.001). Conclusions No progressive pupil narrowing was observed using low-energy FLACS. Although a suction-induced, slight increase in pupil area became apparent, this effect was completely reversible after removing the laser interface.
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Han, Tian, Feng Zhao, Xun Chen, Huamao Miao, Zhuoyi Chen, and Xingtao Zhou. "Evaluation of disk halo size after small incision lenticule extraction (SMILE)." Graefe's Archive for Clinical and Experimental Ophthalmology 257, no. 12 (October 29, 2019): 2789–93. http://dx.doi.org/10.1007/s00417-019-04481-1.
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Abstract Purpose To investigate changes in objective disk halo size produced by a glare source after small incision lenticule extraction (SMILE) for myopia correction. Methods This prospective clinical study included 45 right eyes of 45 patients with a mean age of 25.40 ± 5.06 years and mean spherical equivalent (SE) of − 6.08 ± 1.90 diopters. Disk halo size was measured with a vision monitor before surgery and at postoperative 1 week and 3 months. Other information was collected, including age, SE, lenticule thickness, lenticule diameter, dark pupil, and pupillary response to light parameters (initial diameter; amplitude, latency, duration, and velocity of contraction; latency, duration, and velocity of dilation; and maximum, minimum, and average pupil size). Results Compared to preoperative values, disk halo size increased significantly at postoperative 1 week (P = 0.026) and returned to baseline at postoperative 3 months (P = 0.349). Preoperative disk halo size significantly correlated with SE (r = − 0.346, P = 0.020), minimum pupil size (r = 0.365, P = 0.014), and average pupil size (r = 0.310, P = 0.038). Disk halo size at postoperative 1 week was significantly correlated with age (r = 0.324, P = 0.030) and minimum pupil size (r = 0.297, P = 0.047). Disk halo size at postoperative 3 months was significantly correlated with lenticule diameter (r = − 0.362, P = 0.015), initial diameter (r = 0.311, P = 0.037), maximum pupil size (r = 0.312, P = 0.037), minimum pupil size (r = 0.440, P = 0.002), and average pupil size (r = 0.373, P = 0.012). Conclusions After SMILE, disk halo size demonstrated a temporary increase and then returned to baseline.
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Chaney, Robert H., Carolyne A. Givens, Melanie F. Aoki, and Michael L. Gombiner. "Pupillary Responses in Recognizing Awareness in Persons with Profound Mental Retardation." Perceptual and Motor Skills 69, no. 2 (October 1989): 523–28. http://dx.doi.org/10.2466/pms.1989.69.2.523.
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Pupil-size changes have been shown to indicate positive or negative reactions to several sensory and psychologic stimuli in normal persons. Whether this could be extended to mentally retarded patients who lack ability for verbal or motor behavior was tested by pupillary responses to several visual, tactile, and auditory stimuli. 24 institutionalized severely and profoundly retarded patients were examined by video camera in their usual environments rather than in a controlled laboratory setting. The videotapes were later projected onto a screen for pupil-size measurements. Pupils dilated with pleasant stimuli, including visualizing a familiar person, soft touch to the arm, music, and soft compliments. There was constriction with presenting an unfamiliar person, rough grasp of the arm, and abrasive noise and harsh commands. The findings demonstrate the existence of pupil reactivity in profoundly retarded persons and suggest such testing as a means of determining which elements of their environment are pleasing or aversive to them.
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CHO, Am, Kageyu NORO, Tetsuri INOUE, Shinya KOSHIE, Atsuko HONDO, T. Iwasaki, and S. Akiya. "Changes of pupil size after viewing Three dimensional TV." Japanese journal of ergonomics 26, Supplement (1990): 250–51. http://dx.doi.org/10.5100/jje.26.supplement_250.
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Shi, Chao, and Ling Rothrock. "An Eye-Tracking Evaluation of Gauge Shapes in Process Control." Proceedings of the Human Factors and Ergonomics Society Annual Meeting 63, no. 1 (November 2019): 2201–5. http://dx.doi.org/10.1177/1071181319631235.
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Operators monitor gauge shapes in control room displays to maintain the status of the refinery control process within normal limits. To test if shapes currently used by operators are effectively designed, two experiments were conducted to test the effectiveness of individual shapes in a Visual Thesaurus toolkit for comprehension and change detection. Moreover, eye tracking technology was used to investigate basic perceptual recognition behaviors of each Visual Thesaurus shape for comprehension and change detection. Thirty-one students from Pennsylvania State University participated in this experiment. It was found that pupil size could be used to track the cognitive load of participants. Correctness was also measured but it was not as sensitive as pupil size, as it did not capture a difference in the effectiveness of shapes.
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Sibley, Ciara, Cyrus K. Foroughi, Cory M. Moclaire, Kenneth M. King, Noelle L. Brown, and Joseph T. Coyne. "Additional Evidence for Pupil Size as a Measure of Within-Task Learning." Proceedings of the Human Factors and Ergonomics Society Annual Meeting 63, no. 1 (November 2019): 54–58. http://dx.doi.org/10.1177/1071181319631173.
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This study sought to improve and extend previously conducted research that demonstrated the ability to capture within-task learning by measuring changes in an individual’s peak pupil size across a task. That research had two limitations that needed to be addressed: the use of pixels (an unstandardized pupil size measurement unit) as the primary metric and the lack of inclusion of a pre-stimulus baseline period. Ninety-two Navy and Marine Corps student pilots performed a spatial orientation aptitude test while their pupillary data were recorded. Notably, a new technique was used to convert pupil data from pixels to millimeters and a pre-stimulus baseline period was added between trials to capture tonic activation. Results revealed that peak pupil sizes significantly reduced across trials (r = -.80). The relationship was still very strong after accounting for a reduction in pupillary tonic activation across trials (r = -.59). These findings provide strong support for prior research that showed that reductions in maximum pupil size can demonstrate learning across trials while completing a task. Importantly, this work improved and extended that research by confirming the results using millimeters, a standardized unit of pupil size, instead of pixels, and accounting for tonic activation.
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Tramonti Fantozzi, Maria Paola, Ottavia Marconi, Federica Simoni, Vincenzo De Cicco, Davide De Cicco, Enrico Cataldo, Massimo Barresi, et al. "Coupling between Trigeminal-Induced Asymmetries in Locus Coeruleus Activity and Cognitive Performance." Symmetry 13, no. 9 (September 11, 2021): 1676. http://dx.doi.org/10.3390/sym13091676.
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In humans, the asymmetry in the masseter electromyographic (EMG) activity during clenching is positively correlated with the degree of pupil size asymmetry (anisocoria) at rest. Anisocoria reveals an asymmetry in LC activity, which may lead to an imbalance in cortical excitability, detrimental to performance. Hereby, we investigated, in individual subjects, the possibility that occlusal correction, which decreases EMG asymmetry, improves performance by balancing LC activity. Cognitive performance, task-related mydriasis, and pupil size at rest were modified by changing the occlusal condition. Occlusal-related changes in performance and mydriasis were negatively correlated with anisocoria changes in only 12/20 subjects. Within this population, spontaneous fluctuations in mydriasis and anisocoria also appeared negatively coupled. Occlusal-related changes in performance and mydriasis were negatively correlated with those in average pupil size (a proxy of average LC activity) in 19/20 subjects. The strongest association was observed for the pupil changes occurring on the side with higher EMG activity during clenching. These findings indicate that the effects of occlusal conditions on cognitive performance were coupled to changes in the asymmetry of LC activity in about half of the subjects, while they were related to changes in the average tonic LC activity in virtually all of them.
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Mojumder, Deb Kumar, Saumil Patel, Kenneth Nugent, John Detoledo, Jongyeol Kim, Nabeel Dar, and Henrik Wilms. "Pupil to limbus ratio: Introducing a simple objective measure using two-box method for measuring early nisocoria and progress of pupillary change in the ICU." Journal of Neurosciences in Rural Practice 6, no. 02 (February 2015): 208–15. http://dx.doi.org/10.4103/0976-3147.153229.
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ABSTRACT Introduction: Measurement of static pupillary size in the ICU is of importance in cases of acutely expanding intracranial mass lesions. The inaccuracies with subjective assessment of pupillary size by medical personnel preclude its use in emergent neurological situations. Objective: To determine if the ratio of pupil to limbus diameter (PLD ratio) measured by a two-box method is a reliable measure of pupil size for detecting early anisocoria and measuring pupillary changes. Materials and Methods: The PLD ratio was defined as the ratio of the pupillary diameter measured at a para-horizontal axial plane with the limbus diameter measured at the same or parallel axial plane. A two-box method was used to estimate the diameters of imaged pupils. Eyes were imaged using an iPhone 4S cellphone camera. Background illumination was measured and kept constant. The pupils of a 78-year-old woman, who presented with a large intra-axial parenchymal hemorrhage, were imaged. The patient had left pupillary miosis in dark but not in bright light. After presenting this case along with the images of the pupillary examination, a group of 21 medical staff were asked several questions on the pupillary examination. Reliability of PLD ratio were assessed via standard error of mean (S.E.M) of PLD ratios for 3 different subjects each imaged under constant illumination and fixation but from different angles to the optical axis. Results: Analysis of questionnaire data together with PLD ratios revealed that ~ 14% and 10% of participants could estimate the pupillary size in darkness and bright light respectively but none were simultaneously accurate indicating that subjective assessment of pupillary size was unreliable. The approach towards a systematic pupillary examination was inconsistent among the participants. The PLD ratio was found to be a reliable measure of pupillary size with standard error of mean below 0.1 mm for the three subjects tested. Conclusion: Static pupillary sizes can be objectively and consistently evaluated using PLD ratios using a two-box method. PLD ratios are resistant, within limits, to changes in imaging angle or choice of para-horizontal axes for measurement.
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Zhu, Meng-Jun, Lin-Lin Du, Jun Chen, Xian-Gui He, Shan-Shan Li, and Hai-Dong Zou. "Photopic pupil size change in myopic orthokeratology and its influence on axial length elongation." International Journal of Ophthalmology 15, no. 8 (August 18, 2022): 1322–30. http://dx.doi.org/10.18240/ijo.2022.08.15.
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AIM: To explore the photopic pupil size behavior in myopic children undergoing overnight orthokeratology (ortho-k) over 1-year period and its effects on the axial elongation. METHODS: A total of 202 Chinese myopic children were enrolled in this prospective clinical trial. Ninety-five subjects in ortho-k group and eighty-eight subjects in spectacle group completed the 1-year study. Axial length (AL) was measured before enrollment and every 6mo after the start of ortho-k. The photopic pupil diameter (PPD) was determined using the Pentacam AXL and measured in an examination room with lighting of 300-310 Lx. Stepwise multiple linear regression analysis was used to identify variables contribution to axial elongation. RESULTS: Compared with spectacle group, the average 1-year axial elongation was significantly slower in the ortho-k group (0.25±0.27 vs 0.44±0.23 mm, P<0.0001). In ortho-k group, PPDs significantly decreased from 4.21±0.62 mm to 3.94±0.53 mm after 1mo of lens wear (P=0.001, Bonferroni correction) and the change lasts for 3-month visit. No significantly change during the other follow-up visits was found (P>0.05, Bonferroni correction). The 4.81 mm PPD may be a possible cutoff point in the ortho-k group. Subjects with PPD below or equal to 4.81 mm tended to have smaller axial elongation compared to subjects with PPD above 4.81 mm after 1-year period (t=-3.09, P=0.003). In ortho-k group, univariate analyses indicated that those with older age, greater degree of myopia, longer AL, smaller baseline PPD (PPDbaseline) experienced a smaller change in AL. In multivariate analyses, older age, greater AL and smaller PPDbaseline were associated with smaller increases in AL. In spectacle group, PPD tended to be stable (P>0.05, Bonferroni correction) and did not affect axial growth. CONCLUSION: PPDs experience significantly decreases at 1-month and 3-month ortho-k treatment. Children with smaller PPD tend to experience slower axial elongation and may benefit more from ortho-k.
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Defenderfer, Jessica, Mary McGarr, and A. Caglar Tas. "Change in Pupil Size Reveals Impact of Simulated-Cochlear Implant Speech on Listening Effort." Journal of Vision 20, no. 11 (October 20, 2020): 1409. http://dx.doi.org/10.1167/jov.20.11.1409.
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Dick, Burkhard H., Shakhsanam Aliyeva, and Mana Tehrani. "Change in pupil size after implantation of an iris-fixated toric phakic intraocular lens." Journal of Cataract & Refractive Surgery 31, no. 2 (February 2005): 302–7. http://dx.doi.org/10.1016/j.jcrs.2004.04.040.
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Carrick, Frederick Robert, Sergio F. Azzolino, Melissa Hunfalvay, Guido Pagnacco, Elena Oggero, Ryan C. N. D’Arcy, Mahera Abdulrahman, and Kiminobu Sugaya. "The Pupillary Light Reflex as a Biomarker of Concussion." Life 11, no. 10 (October 18, 2021): 1104. http://dx.doi.org/10.3390/life11101104.
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The size of our pupils changes continuously in response to variations in ambient light levels, a process known as the pupillary light reflex (PLR). The PLR is not a simple reflex as its function is modulated by cognitive brain function and any long-term changes in brain function secondary to injury should cause a change in the parameters of the PLR. We performed a retrospective clinical review of the PLR of our patients using the BrightLamp Reflex iPhone app. The PLR variables of latency, maximum pupil diameter (MaxPD), minimum pupil diameter (MinPD), maximum constriction velocity (MCV), and the 75% recovery time (75% PRT) were associated with significant differences between subjects who had suffered a concussion and those that had not. There were also significant differences in PLR metrics over the life span and between genders and those subjects with and without symptoms. The differences in PLR metrics are modulated not only by concussion history but also by gender and whether or not the person has symptoms associated with a head injury. A concussive injury to the brain is associated with changes in the PLR that persist over the life span, representing biomarkers that might be used in clinical diagnosis, treatment, and decision making.
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Khatsevich, T. N., and E. V. Shmelev. "Investigation of a telescopic systems with three-stage magnification change and a stable exit pupil position." Vestnik SSUGT (Siberian State University of Geosystems and Technologies) 27, no. 5 (2022): 173–82. http://dx.doi.org/10.33764/2411-1759-2022-27-5-173-182.
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The visual optical systems with three fields of view are considered in the article. The removal of the exit pupil of the considered systems is from 1/3 to 1/4 of its total length. The problems that arise during a three-stage change of magnification are considered in the paper. An important feature of such systems is the need to match the pupils of the system when changing the magnification to ensure the stability of the position of the exit pupil. The complexity of the implementation while observing weight and size restrictions are also discussed. A comprehensive solution to these problems should be laid at the circuit level and should be based on the search for a fundamental structural optical scheme. During the design process, the issues of modeling and determining the area of solutions are revealed, which make it possible to ensure high image quality in the transition to finite apertures and thicknesses. The scientific hypothesis is that a three-stage change of magnification can be realized by presence of the rotary afocal system of magnification change. At the same time, for such a solution, internal alignment and competitive characteristics of the optical system of the product as a whole are also provided. The purpose of this article is to present the results of the analysis of the circuit solution in the paraxial approximation, to determine the areas of solutions that provide the smallest relative apertures of the circuit components under the introduced overall restrictions on the length of the system, the diameters of the components and the removal of the exit pupil. The results of the study are confirmed by the development of an optical system with interchangeable magnifications of 1x, 3x and 9x with an eye relief of 80 mm with the total system length of 250 mm.
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Mitre-Hernandez, Hugo, Jorge Sanchez-Rodriguez, Sergio Nava-Muñoz, and Carlos Lara-Alvarez. "Classifying the difficulty levels of working memory tasks by using pupillary response." PeerJ 10 (March 29, 2022): e12864. http://dx.doi.org/10.7717/peerj.12864.
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Knowing the difficulty of a given task is crucial for improving the learning outcomes. This paper studies the difficulty level classification of memorization tasks from pupillary response data. Developing a difficulty level classifier from pupil size features is challenging because of the inter-subject variability of pupil responses. Eye-tracking data used in this study was collected while students solved different memorization tasks divided as low-, medium-, and high-level. Statistical analysis shows that values of pupillometric features (as peak dilation, pupil diameter change, and suchlike) differ significantly for different difficulty levels. We used a wrapper method to select the pupillometric features that work the best for the most common classifiers; Support Vector Machine (SVM), Decision Tree (DT), Linear Discriminant Analysis (LDA), and Random Forest (RF). Despite the statistical difference, experiments showed that a random forest classifier trained with five features obtained the best F1-score (82%). This result is essential because it describes a method to evaluate the cognitive load of a subject performing a task using only pupil size features.
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Erdem, Uzeyir, Fatih C. Gundogan, Umut Aslı Dinc, Umit Yolcu, Abdullah Ilhan, and Salih Altun. "Acute Effect of Cigarette Smoking on Pupil Size and Ocular Aberrations: A Pre- and Postsmoking Study." Journal of Ophthalmology 2015 (2015): 1–5. http://dx.doi.org/10.1155/2015/625470.
Full textAbstract:
Aim.To evaluate the acute effects of cigarette smoking on photopic and mesopic pupil sizes and wavefront aberrations.Methods.Cigarette smoker volunteers were recruited in the study. Photopic and mesopic pupil sizes and total ocular aberrations were measured before smoking and immediately after smoking. All volunteers were asked to smoke a single cigarette containing 1.0 mg nicotine. Pupil sizes and total ocular aberrations were assessed by optical path difference scanning system (OPD-Scan II ARK-10000, NIDEK). Only the right eyes were considered for statistical analysis. The changes of pupil size and total ocular aberrations after smoking were tested for significance by Wilcoxon signed ranks test.Results.Mean photopic pupil size decreased from 3.52 ± 0.73 mm to 3.29 ± 0.58 mm(P=0.001)after smoking. Mean mesopic pupil size was also decreased from 6.42 ± 0.75 mm to 6.14 ± 0.75 mm after smoking(P=0.001). There was a decrease in all the measured components of aberrations (total wavefront aberration, higher-order aberration, total coma, total trefoil, total tetrafoil, total spherical aberration and total higher-order aberration) after smoking; however the differences were insignificant for all(P>0.05).Conclusion.Our results indicate that pupil constricts after smoking. On the other hand, smoking does not alter ocular aberrations.
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Kwon, Hyeok, and Koon-Ja Lee. "Changes of High Order Aberration with Pupil Size and Pupil Center Offset in Young Myopic Eyes." Korean Journal of Vision Science 23, no. 2 (June 30, 2021): 219–29. http://dx.doi.org/10.17337/jmbi.2021.23.2.219.
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