Pupil Size Variation Research Articles

Analysis of the optical performance of intraocular lenses using profilometric measurements.

The aim of this study was to develop a methodology, based on profilometer measurements to assess the optical behaviour of Intraocular Lenses (IOls). The "Modulation Transfer Function through-object" (MTF through-object) based on vergence object displacement was calculated for different pupil sizes and pseudophakic eyes. Tilt and decentration were also analysed in a realistic cornea eye model. For comparison between the different IOLs, an optical quality criterion based on a minimum value the MTF through-object and the recognition of simulated vision optotypes was introduced. Five IOLs were used in this study: Tecnis Eyhance, Mini Well, Tecnis Symfony, Tecnis Synergy and RayOne EMV. The technique was validated with previous methodologies. A general narrowing of the through-object MTF curve compared to the through-focus MTF curve was shown, resulting in greater distances between near and intermediate points and less depth of field around the far peak. The comparison between the IOLs showed that variations in corneal aberrations, pupil size and decentration caused relevant changes in IOL performance. A decrease of the SA produced a hypermetropic shift of the far focus between + 0.3 D and + 0.4 D. Most of IOLs worsen the optical quality as pupil size increased, even the MTF through-object shape changed. Decentration was an important factor in IOL implantation, causing a significant change in MTF through-object shape in most of IOLs. This study highlights the need to evaluate pre-operative patients for corneal aberrations and pupillary size to have the best optical success after cataract surgery in multifocal or extended depth of focus IOLs. What is known MTF(Modulation Transfer Function)through-focus curves (calculated in image space by moving the detector plane) can be obtained from optical bench assembly or from commercial devices. Recently, some studies proposed to characterize the lens surface design based on the profilometric measurements What is new A novel methodology based on profilometer measurements to assess the optical behaviour of Intraocular Lenses (IOls) was shown. The "Modulation Transfer Function through-object" based on vergence object displacement was introduced in order to analyse five premium IOLs. MTF through-object curve is more appropriate for studying clinical behaviour, as it provides further near and intermediate points distances and lower depth of focus around far peak compare to MTF through-focus curves. The optical behaviour of the five IOLs can vary considerably depending on the eye model and pupil size. The effect of tilt and decentration on the MTF through-object the IOLs was analysed.

A Study on the Accuracy of Micro Expression Based Deception Detection with Hybrid Deep Neural Network Models

This article details a study on enhancing deception detection accuracy by using Hybrid Deep Neural Network (HDNN) models. The research, focusing on fear-related micro-expressions, utilizes a diverse dataset of responses to high-stakes questions. It analyzes facial action units (AUs) and pupil size variations through data preprocessing and feature extraction. The HDNN model outperforms the traditional Convolutional Neural Network (CNN) with a 91% accuracy rate. The findings’ implications for security, law enforcement, psychology, and behavioral treatments are discussed. Ethical considerations of deception detection technology deployment and future research directions, including cross-cultural studies, real-world assessments, ethical guidelines, studies on emotional expression dynamics, “explainable AI” development, and multimodal data integration, are also explored. The study contributes to deception detection knowledge and highlights the potential of machine learning techniques, especially HDNN, in improving decision-making and security in high-stakes situations.

Advancing the understanding of pupil size variation in occupational safety and health: A systematic review and evaluation of open-source methodologies

Pupil size can be used as an important biomarker for occupational risks. In recent years, there has been an increase in the development of open-source tools dedicated to obtaining and measuring pupil diameter. However, it remains undetermined determined whether these tools are suitable for use in occupational settings. This study explores the significance of pupil size variation as a biomarker for occupational risks and evaluates existing open-source methods for potential use in both research and occupational settings, with the goal of to prevent occupational accidents and improve the health and performance of workers. To this end, a two-phase systematic literature review was conducted in the Web of Science™, ScienceDirect®, and Scopus® databases. For the relevance of monitoring pupil size variation in occupational settings, 15 articles were included. The articles were divided into three groups: mental workload, occupational stress, and mental fatigue. In most cases, pupil dilation increased with workload enhancement and with higher levels of stress. Regarding fatigue, it was noted that an increase in this condition corresponded with a decrease in pupil size. With respect to the open-source methodologies, 16 articles were identified, which were categorized into two groups: algorithms and software. Convolutional neural networks (CNN)11CNN: Deep learning models adept at processing large datasets for 2D image analysis. These CNNs, by convolving images with filters, excel at extracting features and achieving high accuracy in image recognition and detection tasks (Chauhan et al., 2018). have exhibited superior performance among the various algorithmic approaches studied. Building on this insight, and considering the evaluations of software options, MEYE emerges as the premier open-source system for deployment in occupational settings due to its compatibility with a standard computer webcam. This feature positions MEYE as a particularly practical tool for workers in stable environments, like those of developers and administrators.

Diurnal Variation in Accommodation, Binocular Vergence, and Pupil Size.

Our results show significant diurnal variations in accommodative function and the magnitude of the phoria. Therefore, when comparing visual measures in clinical or laboratory settings, performing the visual examination at the same time of day (±1 hour) is encouraged. The aim of this study was to evaluate the accommodation, binocular vergence, and pupil behavior on three different times during the day. Twenty collegiate students (22.8 ± 2.1 years) participated in this study. Participants visited the laboratory on three different days at 2-hourly intervals (morning, 9:00 to 11:00 am ; afternoon, 2:00 to 4:00 pm ; evening, 7:00 to 9:00 pm ). The binocular vergence and accommodative function were measured using clinical optometric procedures, and the accommodative response and pupil function were evaluated in binocular conditions using the WAM-5500 autorefractometer. The accommodative amplitude for the right and left eyes showed statistically significant differences for the time interval ( P = .001 and P = .02, respectively), revealing higher accommodative amplitude in the morning and afternoon in comparison with the evening. Participants were more esophoric when assessed in the morning in comparison with the evening at far and near ( P = .02 and P = .01, respectively) and when assessed in the afternoon in comparison with the evening at far distance ( P = .02). The magnitude of accommodative response was higher in the morning, and it decreased throughout the day at 500 ( P < .001), 40 ( P = .05), and 20 cm ( P < .001). No statistically significant differences were obtained for any other variable. This study shows small diurnal variations in some accommodative and binocular vergence parameters, but no effects were observed for the pupil response. These outcomes are of special relevance for eye care specialists when performing repeated accommodative or binocular vergence measures. However, the diurnal variations were modest and may not influence a routine orthoptic examination.

Refractive extended depth-of-focus lens design based on periodic power profile for presbyopia correction.

Limitations of existing diffractive multifocal designs for presbyopia correction include discrete foci and photic phenomena such as halos and glare. This study aimed to explore a methodology for developing refractive extended depth-of-focus (EDoF) lenses based on a periodic power profile. The proposed design technique employed an optical power profile that periodically alternated between far, intermediate and near distances across the pupil radius. To evaluate the lens designs, optical bench testing was conducted. The impact on visual performance was assessed using a spatial light modulator-based adaptive optics vision simulator in human subjects. Additionally, the effects of pupil size change and lens decentration on retinal image quality were examined. A comparative performance analysis was carried out against a typical diffractive trifocal design and a monofocal lens. The proposed design method was found to be effective in uniformly distributing light energy across all object distances within the desired depth of focus (DoF). While trade-offs between overall image quality and DoF still exist, the EDoF lens design, when tested in human subjects, provided a continuous DoF spanning over 2.25 D. The results also revealed that the EDoF design had a slightly higher dependence on changes in pupil size and lens decentration than the diffractive trifocal design. The proposed design method showed significant potential as an approach for developing refractive EDoF ophthalmic lenses. These lenses offer a continuous DoF but are slightly more susceptible to variations in pupil size and decentration compared with the diffractive trifocal design.

From pupil to the brain: New insights for studying cortical plasticity through pupillometry.

Pupil size variations have been associated with changes in brain activity patterns related with specific cognitive factors, such as arousal, attention, and mental effort. The locus coeruleus (LC), a key hub in the noradrenergic system of the brain, is considered to be a key regulator of cognitive control on pupil size, with changes in pupil diameter corresponding to the release of norepinephrine (NE). Advances in eye-tracking technology and open-source software have facilitated accurate pupil size measurement in various experimental settings, leading to increased interest in using pupillometry to track the nervous system activation state and as a potential biomarker for brain disorders. This review explores pupillometry as a non-invasive and fully translational tool for studying cortical plasticity starting from recent literature suggesting that pupillometry could be a promising technique for estimating the degree of residual plasticity in human subjects. Given that NE is known to be a critical mediator of cortical plasticity and arousal, the review includes data revealing the importance of the LC-NE system in modulating brain plasticity and pupil size. Finally, we will review data suggesting that pupillometry could provide a quantitative and complementary measure of cortical plasticity also in pre-clinical studies.

Emotion Detection Based on Pupil Variation.

Emotion detection is a fundamental component in the field of Affective Computing. Proper recognition of emotions can be useful in improving the interaction between humans and machines, for instance, with regard to designing effective user interfaces. This study aims to understand the relationship between emotion and pupil dilation. The Tobii Pro X3-120 eye tracker was used to collect pupillary responses from 30 participants exposed to content designed to evoke specific emotions. Six different video scenarios were selected and presented to participants, whose pupillary responses were measured while watching the material. In total, 16 data features (8 features per eye) were extracted from the pupillary response distribution during content exposure. Through logistical regression, a maximum of 76% classification accuracy was obtained through the measurement of pupillary response in predicting emotions classified as fear, anger, or surprise. Further research is required to precisely calculate pupil size variations in relation to emotionally evocative input in affective computing applications.

Characterisation of pupillary responses to alternating blue and orange light exposures in a fMRI protocol

AbstractBackgroundThe non‐image forming (NIF) functions of light are diverse and include stimulation of cognition and alertness, sleep regulation and pupil diameter modulation. Previous work indicated that exposure to blue‐enriched light as well as pupil size variations are associated with higher locus coeruleus (LC) activity. Given the central role of LC structure and function in the earliest stages of Alzheimer’s disease neuropathology, light exposure may constitute a promising stimulation technique to delay disease progression. Prior to addressing light impact on the LC, here, we aimed at characterising the pupil responses to light during fMRI protocol, to determine its quality in assessing NIF effects of light.MethodPupil diameter was continuously recorded in 11 healthy subjects (20‐30yr, 7 women) with an infrared eyetracker device while they were administered a 15‐min auditory oddball task in a 7T MRI scanner. Participants were concomitantly exposed to pseudo‐randomly alternating 30s blocks of blue‐enriched (4,000K; 200µW/cm2) and orange (589nm; 6x1013photons/cm2/s) lights. Statistics consisted in generalized linear mixed models seeking effects of light condition on pupil response, with subjects as random intercept and controlling for age, sex and BMI.ResultBlue light condition was associated with a significantly smaller pupil diameter as compared to the orange condition, (main effect of light condition: F(2,270)=571.22;p&lt;.0001; Fig1). Moreover, the impact of the light condition on pupil size did not significantly change over the 15min‐protocol (light condition x block repetition interaction: F(12,240)=1.21 ; p=.28), suggesting that time‐in‐protocol and prior light blocks did not influence pupil constriction.ConclusionWe report preliminary results confirming that blue‐enriched light triggers a stronger pupil response than longer wavelength light and showing that the protocol induces a stable response in time even when using short alternating light exposures. These findings support the validity of the protocol to assess NIF responses to light in fMRI in healthy participants, including over the LC. Being able to stimulate the LC holds important implications for possibly delaying Alzheimer’s disease progression. We now aim to include more participants, including older individuals, and to extend to other cognitive tasks to assess the generalization of the present findings to other cognitive domains and age‐ranges.

The virtualization of human–robot interactions: a user-centric workload assessment

Interest in the virtualization of human–robot interactions is increasing, yet the impact that collaborating with either virtual or physical robots has on the human operator’s mental state is still insufficiently studied. In the present work, we aimed to fill this gap by conducting a systematic assessment of a human–robot collaborative framework from a user-centric perspective. Mental workload was measured in participants working in synergistic co-operation with a physical and a virtual collaborative robot (cobot) under different levels of task demands. Performance and implicit and explicit workload were assessed as a function of pupil size variation and self-reporting questionnaires. In the face of a similar self-reported mental demand when maneuvering the virtual or physical cobot, operators showed shorter operation times and lower implicit workload when interacting with the virtual cobot compared to its physical counterpart. Furthermore, the benefits of collaborating with a virtual cobot most vividly manifested when the user had to position the robotic arm with higher precision. These results shed light on the feasibility and importance of relying on multidimensional assessments in real-life work settings, including implicit workload predictors such as pupillometric measures. From a broader perspective, our findings suggest that virtual simulations have the potential to bring significant advantages for both the user's mental well-being and industrial production, particularly for highly complex and demanding tasks.

Accepting Human-like Avatars in Social and Professional Roles

Humans report perceptions of unease or eeriness as humanoid/android robots and digital avatars approach human-like physical resemblance, a phenomenon alluded by the Uncanny Valley theory. This study extends the discussions on interactions and acceptance of digital avatars with findings from three experiments. In the first, perceptive evaluation of actors in clips from computer-generated animation and a live-action version of the same movie was examined. In the second experiment, we considered short clips with highly realistic digital avatars to measure recognition ability, the extent of eeriness, and specific physical features identified as unreal. The fixation area and pupil size variation recorded using an eye tracker were analyzed to infer attention to the body, face, and emotional response, respectively. Building on these findings, the third experiment looked at acceptance in roles requiring human skill, empathy, and cognitive ability. The results show that based on perceptions from physical attributes, the eeriness scores diverge from the uncanny valley theory as human-likeness increases. The realistic CGI and mocap technology could have helped cross the valley. Visual attention inferred from gaze behavior was similar for live-action and CGI. At the same time, we observe pupil size changes reflecting emotions like eeriness when the avatars either talked or smiled. Proficiency and acceptance scores were lower for roles requiring complex social cognition processes, such as friends and judicial decision-making. Interestingly, real-life stereotypes of gender roles were transferred to digital avatars too. The findings suggest an ambiguity in accepting human-like avatars in social and professional interactions, emphasizing the need for a multi-dimensional approach when applying the uncanny valley theory. A detailed and contextual examination is imperative as technological advancements have placed humans closer to co-existing with digital or physical android/humanoid robots.

Variations in Pupil Size Related to Memory for Recently Presented Words and Event Related Potentials.

Pupillometry has been found to be correlated with activity of cholinergic and noradrenergic neuromodulator systems. These systems regulate the level of cortical arousal and therefore perception, attention, and memory. Here, we tested how different types of pupil size variance (prestimulus baseline and prestimulus hippus power) may correlate with behavioral and event-related potentials (ERPs). We recorded pupil size and ERPs while participants were presented with a series of words and then asked whether the words had been in the initial list when they were later presented intermixed with unpresented words. We found that a smaller prestimulus baseline pupil size during the study phase was associated with better memory performance. Study items also evoked a larger P3 response at presentation and a greater old/new memory ERP effect at test when prestimulus pupil size was small rather than large. Prestimulus hippus power was found to be a between-subjects factor affecting the robustness of memory encoding with less power being associated with a greater old/new memory ERP effect. These results provide evidence relating memory and ERPs to variables defined on pupil size that are thought to reflect varying states of parasympathetic and sympathetic arousal.

“Context-Dependent Cognitive Workload Monitoring using Pupillometry for Control Room Operators to Prevent Overload”

Occupational Application Modernization of process plants has replaced traditional machine control with sophisticated computerized control, with the work required of control room operators changing from predominantly physical to cognitive. As a result, excessive cognitive workload during an abnormal condition is not an uncommon situation. Almost 70% of accidents in process industries are the result of human error, which is largely modulated by high cognitive workload. A context-dependent methodology using pupillometry was adopted in this study for workload assessment. We found that workload has a significant effect on task performance and subsequent success in handling an abnormal condition. Incorporating contextual information along with pupillometry-based measures was useful to explore the dynamics of variations in workload in depth. In addition, the proposed methodology is a more reliable method for a dynamic environment in which the situation evolves with operator interactions with the process. Technical : Background: Operator workload monitoring has become an important aspect of system engineering due to ever increasing cognitive demands in the control room. Higher cognitive workload, beyond capability, is directly associated with human error in plant operations. Even a small increase in workload during peak demand may result in human error, which can endanger the safety of a process plant. Purpose: Subjective methods are of limited use due to the requirement for near real-time evaluation of cognitive workload. Applications such as process plant control room require the operator to reiterate and re-represent the situation based on the contextual cues from environment. Hence, our objective was to develop and test a methodology that incorporates contextual information in workload measurement using pupillometry. Method: Participants (n = 44) performed simulated process control tasks. Pupil size was recorded using an eye-tracking device. Recorded pupil size was analyzed based on a methodology that incorporates contextual information from the human-machine interface. Events that present new information about the current state of the process were categorized as critical events. Pupil size variation was adopted to provide an estimate of cognitive workload between consecutive critical events. Results: Cognitive workload was associated with process behavior and operator actions. An increase in cognitive workload for specific events was observed when participant actions deteriorated process conditions. We also observed that overall task performance was associated with the frequency of certain events and corresponding variations in pupillary behavior. Conclusion: Incorporating contextual information provides more detailed insights into the dynamics of variations in cognitive workload. The mental representation of a current situation may vary depending on expertise level. The proposed methodology assesses such dynamic mental representations in the form of frequency of critical events and corresponding changes in the cognitive workload that ultimately determines the likelihood of an operator successfully completing a task.

Pupil size variations reveal covert shifts of attention induced by numbers

The pupil light response is more than a pure reflexive mechanism that reacts to the amount of light entering the eye. The pupil size may also react to the luminance of objects lying in the visual periphery, revealing the locus of covert attention. In the present study, we took advantage of this response to study the spatial coding of abstract concepts with no physical counterpart: numbers. The participants' gaze was maintained fixed in the middle of a screen whose left and right parts were dark or bright, and variations in pupil size were recorded during an auditory number comparison task. The results showed that small numbers accentuated pupil dilation when the darker part of the screen was on the left, while large numbers accentuated pupil dilation when the darker part of the screen was on the right. This finding provides direct evidence for covert attention shifts on a left-to-right oriented mental spatial representation of numbers. From a more general perspective, it shows that the pupillary response to light is subject to modulation from spatial attention mechanisms operating on mental contents.

Editorial Issue 33.2

This issue contains five papers. In the first paper, Ege Tekgün, Muhtar Çağkan Uludağlı, Hüseyin Akcan, and Burak Erdeniz, from Izmir University of Economics in Turkey assess the influence of virtual avatar anthropomorphism and the synchronicity of the visuo-tactile stimulation on self-location using a virtual reality (VR) full-body illusion (FBI) experiment. During the experiment, half of the 36 participants observed a gender-matched full-body humanoid avatar from a first-person perspective (1PP) and the other half observed a less anthropomorphic full-body cubical avatar from 1PP while they were receiving synchronous and asynchronous visuo-tactile stimulation. Results show a significant main effect of the synchronicity of the visuo-tactile stimulation and avatar body type on self-location but no significant interaction was found between them. Moreover, the results of the self-report questionnaire provide additional evidence showing that participants who received synchronous visuo-tactile stimulation, experienced not only greater changes in the feeling of self-location, but also, increased ownership, and referral of touch. In the second paper, Ke Li, Qian Zhang, Jinyuan Jia, from Tongji University in Shanghai, China, and Hantao Zhao, from Southeast University in Nanjing, all in China discuss the technology of presenting building information modeling (BIM) with an online platform and the difficulty to display large-scale BIM scenes in a flawless manner on mobile browsers, due to network bandwidth and browser performance limitations. The authors propose CEBOW, a Cloud-Edge-Browser Online architecture for visualizing BIM components with online solutions. The method combines transmission scheduling, cache management, and optimal initial loading into a single system architecture. For network transmission testing, BIM scenes are used, and the results show that their method effectively reduces scene loading time and networking delay while improving the visualization effect of large-scale scenes. In the third paper, Yuzhu Dong and Eakta Jain, from University of Florida in Gainesville, and Sophie Jörg, from Clemson University, all in United States discuss how the importance of eyes for virtual characters stems from the intrinsic social cues. They emphasize that the eye animation impacts the perception of an avatar's internal emotional state. They present three large scale experiments that investigate the extent to which viewers can identify if an avatar is scared. The authors find that participants can identify a scared avatar with 75% accuracy using cues in the eyes including pupil size variation, gaze, and blinks. Because eye trackers return pupil diameter in addition to gaze, their experiments inform practitioners that animating the pupil correctly will add expressiveness to a virtual avatar with negligible additional cost. These findings also have implications for creating expressive eyes in intelligent conversational agents and social robots. The fourth paper, by Osman Güler, from TUSAŞ Şehit Hakan Gülşen Vocational and Technical Anatolian High School in Ankara and Serkan Savaş, from Çankırı Karatekin Üniversitesi, both in Turkey present a study showing that Interactive Boards (IBs) have the necessary hardware to run Stereoscopic 3D (S3D) training materials, but the panel has not got an S3D imaging feature. Therefore, only the Anaglyph S3D imaging method can be applied to IBs. Thus, an Anaglyph S3D training material was prepared for the interaction of the skeletal system and interactive 3D material design for IBs with its effects in education was investigated. A Likert-type scale was developed to measure the usability of the training material on IBs and the material was evaluated by 20 experts. The data were analyzed by the SPSS statistical program and the results were interpreted. According to the results, educational material seems to be positive in terms of image characteristics, content, navigation, and ease of use, font sizes were moderate for readability, the feedback process and the help menu were moderately effective. The last paper by Alexandra Sierra, Marie Postma, from Tilburg University in Netherlands and Menno Van Zaanen, from North-West University in Potchefstroom, South Africa investigate whether the uncanny valley effect, which has already been found for the human-like appearance of virtual characters, can also be found for animal-like appearances. They conducted an online study in which six different animal designs were evaluated in terms of the following properties: familiarity, commonality, naturalness, attractiveness, interestingness, and animateness. The study participants differed in age (under 10–60 years) and origin (Europe, Asia, North America, and South America). For the evaluation of the results, the authors ranked the animal-likeness of the character using both expert opinion and participant judgments. They also investigated the effect of movement and morbidity. The results confirm the existence of the uncanny valley effect for virtual animals, especially with respect to familiarity and commonality, for both still and moving images. No uncanny valley effect was detected for interestingness and animateness.

Is the avatar scared? Pupil as a perceptual cue

AbstractThe importance of eyes for virtual characters stems from the intrinsic social cues in a person's eyes. While previous work on computer generated eyes has considered realism and naturalness, there has been little investigation into how details in the eye animation impact the perception of an avatar's internal emotional state. We present three large scale experiments (N≈500) that investigate the extent to which viewers can identify if an avatar is scared. We find that participants can identify a scared avatar with accuracy using cues in the eyes including pupil size variation, gaze, and blinks. Because eye trackers return pupil diameter in addition to gaze, our experiments inform practitioners that animating the pupil correctly will add expressiveness to a virtual avatar with negligible additional cost. These findings also have implications for creating expressive eyes in intelligent conversational agents and social robots.

A Mixed Statistical and Machine Learning Approach for the Analysis of Multimodal Trail Making Test Data

Eye-tracking can offer a novel clinical practice and a non-invasive tool to detect neuropathological syndromes. In this paper, we show some analysis on data obtained from the visual sequential search test. Indeed, such a test can be used to evaluate the capacity of looking at objects in a specific order, and its successful execution requires the optimization of the perceptual resources of foveal and extrafoveal vision. The main objective of this work is to detect if some patterns can be found within the data, to discern among people with chronic pain, extrapyramidal patients and healthy controls. We employed statistical tests to evaluate differences among groups, considering three novel indicators: blinking rate, average blinking duration and maximum pupil size variation. Additionally, to divide the three patient groups based on scan-path images—which appear very noisy and all similar to each other—we applied deep learning techniques to embed them into a larger transformed space. We then applied a clustering approach to correctly detect and classify the three cohorts. Preliminary experiments show promising results.

Implementation of the Frequency Scatter Index in Clinical Commercially Available Double-pass Systems

ABSTRACTA previous work has reported a methodology to quantify intraocular scattering using a high sensitivity double-pass instrument with a robust index, the frequency scatter index. The purpose of our study was to evaluate an adaptation of the frequency scatter index for use in clinical double-pass systems. A prospective observational study was carried out in a group of patients with nuclear cataracts (n = 52) and in a control group (n = 11) using conventional double-pass systems. The frequency scatter index and the objective scatter index were used to assess the scattering. The Spearman coefficient was calculated to assess the correlation between both indexes, obtained from the double-pass images. Simultaneous measurements were performed with a double-pass and with a Hartmann-Shack wavefront sensor in the control group. The root-mean-square wavefront error and the full width at half maximum of the double-pass image were used to quantify the residual aberrations introduced by the variations in pupil size and retinal eccentricity. Measurement in eyes with different grades of cataracts shows a strong correlation (ρ = 0.929, p < .0001) between the frequency scatter index and the objective scatter index. A certain degree of correlation was observed between the objective scatter index and the root-mean-square and between the objective scatter index and the full width at half maximum, both for measurements with a different pupillary diameter and with a different retinal eccentricity (p < .05). No relationship was observed between the frequency scatter index and the root-mean-square or between the frequency scatter index and the full width at half maximum (p > .05). We have introduced and evaluated an adaptation of a methodology proposed recently for the measurement of intraocular scattering using the double-pass technique with a robust index, which is less affected by ocular aberrations. The frequency scatter index can be applied to conventional double-pass instruments available in clinical environments.

The cognitive workload of air pistol shooters on the aiming task

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

Pupil size variation in primary facial expressions–testing potential biomarker of self-criticism

Pupil size variation in primary facial expressions–testing potential biomarker of self-criticism

Optical coherence tomography angiography application to pigmented iris: Could a new index quantify blood flow?

To assess the blood flow and vascular visibility of irises in relation to pigmentation and pupil size, using an anterior segment optical coherence tomography angiography (OCTA). This is a cross-sectional study. OCTA images were acquired in the nasal and temporal quadrants from a cohort of 30 healthy subjects in photopic (miosis) and scotopic (mydriasis) conditions. Patients were divided according to iris color (less pigmented: group L vs more pigmented: group D). Vascular parameters (vessel density (VD), vessel length density (VLD), fractal dimension (FD)) were applied and compared among groups L and D, location and different pupil status. A novel vascular index called Luminance Index (LI) was developed and applied in order to quantify vascular flow and evaluate its variation in photopic and scotopic conditions. Multivariable analyses were performed to evaluate possible predictors of VD and LI. No differences were found for all vascular measurements (VD, VDL, FD, LI) between nasal and temporal quadrants. All vascular measurements were higher in group L than in group D (p < 0.05), except for LI and FD in photopic condition. In group L, all vascular parameters increased (p < 0.001) after dark adaptation. In group D, only LI increased after dark adaptation (p < 0.001). Pigmentation and iris thickness were significantly associated with VD in scotopic and photopic conditions, and with LI only in scotopic condition. Pigmentation still remains a major issue for vascular visibility. Quantitative and qualitative vascular changes follow pupil size variation. LI could be a new surrogate to quantify blood flow.