Quantitative pupillometry as a biomarker for prediction of return to play in mild traumatic brain injury: a Military Traumatic Brain Injury Initiative study.

OBJECTIVE: This study aimed to determine the validity of quantitative pupillometry to predict the length of time for return to full activity/duty after a mild traumatic brain injury (mTBI) in a cohort of injured cadets at West Point. METHODS: Each subject received baseline (T0) quantitative pupillometry, in addition to evaluation with the Balance Error Scoring System (BESS), Standardized Assessment of Concussion (SAC), and Sport Concussion Assessment Tool 5th Edition Symptom Survey (SCAT5). Repeat assessments using the same parameters were conducted within 48 hours of injury (T1), at the beginning of progressive return to activity (T2), and at the completion of progressive return to activity protocols (T3). Pupillary metrics were compared on the basis of length of time to return to full play/duty and the clinical scores. RESULTS: The authors' statistical analyses found correlations between pupillometry measures at T1, including end-initial diameter and maximum constriction velocity, with larger change and faster constriction predicting earlier return to play. There was also an association with maximum constriction velocity at baseline (T0), predicting faster return to play. CONCLUSIONS: The authors conclude that that pupillometry may be a valuable tool for assessing time to return to duty from mTBI by providing a measure of baseline resiliency to mTBI and/or autonomic dysfunction in the acute phase after mTBI.

Pupillary Responses to Dynamic Negative Versus Positive Facial Expressions of Emotion in Children and Parents: Links to Depression and Anxiety.

Witnessing emotional expressions in others triggers physiological arousal in humans. The current study focused on pupil responses to emotional expressions in a community sample as a physiological index of arousal and attention. We explored the associations between parents' and offspring's responses to dynamic facial expressions of emotion, as well as the links between pupil responses and anxiety/depression. Children (N = 90, MAge = 10.13, range = 7.21-12.94, 47 girls) participated in this lab study with one of their parents (47 mothers). Pupil responses were assessed in a computer task with dynamic happy, angry, fearful, and sad expressions, while participants verbally labeled the emotion displayed on the screen as quickly as possible. Parents and children reported anxiety and depression symptoms in questionnaires. Both parents and children showed stronger pupillary responses to negative versus positive expressions, and children's responses were overall stronger than those of parents. We also found links between the pupil responses of parents and children to negative, especially to angry faces. Child pupil responses were related to their own and their parents' anxiety levels and to their parents' (but not their own) depression. We conclude that child pupils are sensitive to individual differences in parents' pupils and emotional dispositions in community samples.

Pupillary Light Reflex Reveals Melanopsin System Alteration in the Background of Myopia-26, the Female Limited Form of Early-Onset High Myopia.

Purpose: The purpose of this study was to evaluate pupillary light reflex (PLR) to chromatic flashes in patients with early-onset high-myopia (eoHM) without (myopic controls = M-CTRL) and with (female-limited myopia-26 = MYP-26) genetic mutations in the ARR3 gene encoding the cone arrestin. Methods: Participants were 26 female subjects divided into 3 groups: emmetropic controls (E-CTRL, N = 12, mean age = 28.6 ± 7.8 years) and 2 myopic (M-CTRL, N = 7, mean age = 25.7 ± 11.5 years and MYP-26, N = 7, mean age = 28.3 ± 15.4 years) groups. In addition, one hemizygous carrier and one control male subject were examined. Direct PLRs were recorded after 10-minute dark adaptation. Stimuli were 1-second red (peak wavelength = 621 nm) and blue (peak wavelength = 470 nm) flashes at photopic luminance of 250 cd/m². A 2-minute interval between the flashes was introduced. Baseline pupil diameter (BPD), peak pupil constriction (PPC), and postillumination pupillary response (PIPR) were extracted from the PLR. Group comparisons were performed with ANOVAs. Results: Dark-adapted BPD was comparable among the groups, whereas PPC to the red light was slightly reduced in patients with myopia (P = 0.02). PIPR at 6 seconds elicited by the blue flash was significantly weaker (P < 0.01) in female patients with MYP-26, whereas it was normal in the M-CTRL group and the asymptomatic male carrier. Conclusions: L/M-cone abnormalities due to ARR3 gene mutation is currently claimed to underlie the pathological eye growth in MYP-26. Our results suggest that malfunction of the melanopsin system of intrinsically photosensitive retinal ganglion cells (ipRGCs) is specific to patients with symptomatic MYP-26, and may therefore play an additional role in the pathological eye growth of MYP-26.

Differences in the pupillary responses to evening light between children and adolescents.

BACKGROUND: In the mammalian retina, intrinsically-photosensitive retinal ganglion cells (ipRGC) detect light and integrate signals from rods and cones to drive multiple non-visual functions including circadian entrainment and the pupillary light response (PLR). Non-visual photoreception and consequently non-visual sensitivity to light may change across child development. The PLR represents a quick and reliable method for examining non-visual responses to light in children. The purpose of this study was to assess differences in the PLRs to blue and red stimuli, measured one hour prior to bedtime, between children and adolescents. METHODS: Forty healthy participants (8-9 years, n = 21; 15-16 years, n = 19) completed a PLR assessment 1 h before their habitual bedtime. After a 1 h dim-light adaptation period (< 1 lx), baseline pupil diameter was measured in darkness for 30 s, followed by a 10 s exposure to 3.0 × 1013 photons/cm2/s of either red (627 nm) or blue (459 nm) light, and a 40 s recovery in darkness to assess pupillary re-dilation. Subsequently, participants underwent 7 min of dim-light re-adaptation followed by an exposure to the other light condition. Lights were counterbalanced across participants. RESULTS: Across both age groups, maximum pupil constriction was significantly greater (p < 0.001, ηp2 = 0.48) and more sustained (p < 0.001, ηp2 = 0.41) during exposure to blue compared to red light. For adolescents, the post-illumination pupillary response (PIPR), a hallmark of melanopsin function, was larger after blue compared with red light (p = 0.02, d = 0.60). This difference was not observed in children. Across light exposures, children had larger phasic (p < 0.01, ηp2 = 0.20) and maximal (p < 0.01, ηp2 = 0.22) pupil constrictions compared to adolescents. CONCLUSIONS: Blue light elicited a greater and more sustained pupillary response than red light in children and adolescents. However, the overall amplitude of the rod/cone-driven phasic response was greater in children than in adolescents. Our findings using the PLR highlight a higher sensitivity to evening light in children compared to adolescents, and continued maturation of the human non-visual photoreception/system throughout development.

Agreement and repeatability of scotopic pupil size measurement with the 2WIN-S portable refractor in Chinese adults.

To assess the agreement and repeatability of scotopic pupil size measurement using 2WIN-S (Adaptica, Padova, Italy) portable refractor in Chinese adults. This prospective non-randomized open-label controlled study assessed the scotopic pupil size of 100 right eyes using OPD-Scan III (Optical path difference) (Nidek Technologies, Gamagori, Japan) and 2WIN-S. OPD-Scan III and 2WIN-S measure pupil size using infrared light and detector, while 2WIN-S measures bilateral eyes simultaneously, OPD-Scan III measures unilateral eyes individually. Participants were first measured once using OPD-Scan III and two consecutive measurements were performed using 2WIN-S after 15 min of rest interval. The primary outcome was to evaluate the agreement between 2WIN-S and OPD-Scan III, and the secondary outcome was to evaluate the repeatability of 2WIN-S. Scotopic pupil size of 100 right eyes of 100 adults (28 male and 72 female) aged 18-53 years (mean 36 ± 12 years) was assessed using OPD-Scan III and 2WIN-S, respectively. The mean scotopic pupil size of OPD-Scan III and 2WIN-S was recorded to be 6.24 ± 0.88 mm and 6.27 ± 0.81 mm, respectively. For the mean scotopic pupil size of OPD-Scan III and 2WIN-S the difference was - 0.03 mm (95%CI - 0.10 to 0.04 mm), p = 0.445, the 95% limits of agreement (LOA) was - 0.71 to 0.66 mm. ICC between the two devices was 0.92 (95% CI 0.88-0.94) (ICC > 0.9 indicates excellent consistency). Coefficients of repeatability (CoR) of 2WIN-S was 0.37, which has a high repeatability. For the mean scotopic pupil size of 2WIN-S of the repeated measurements, the difference was -0.04 mm (95%CI - 0.08 to 0.01 mm), p = 0.019, the 95% limits of agreement (LOA) was - 0.41 to 0.32 mm, with a narrow LOA. However, the majority of the variations were less than ± 0.50 mm (98% of scotopic pupil size measurements were below this threshold), within the clinically acceptable range (± 0.50 mm). Our study showed excellent agreement between 2WIN-S and OPD-Scan III (ICC > 0.9) and a good repeatability of 2WIN-S (CoR = 0.37). This study suggests a novel technique for measuring pupillary responses in low light conditions, which can be considered an alternative to OPD-Scan III in clinical settings.

Population study of pupillary unrest in ambient light.

INTRODUCTION: Pupillary unrest in ambient light (PUAL) describes the fluctuation of pupil diameter observed in normal, awake subjects under typical levels of indoor light. PUAL becomes low to absent in young healthy subjects during opioid intoxication. We sought to determine the age-related distribution of PUAL values in a random sample of ambulatory participants. METHODS: Subjects ≥18 years of age were recruited. All were identified by age range (18-29, 30-49, 50-69, and ≥70), and surveyed for diabetes, beta-blocker use, and prior 24-hour opioid use. Relationship between mean PUAL, age group, comorbidity and opioid use were examined by Kruskal Wallis test, and PUAL and was modeled using stepwise multilevel linear regression, including diabetes, beta blocker use, prior 24-hour opioid use, autonomic dysfunction, and pupil diameter as fixed effects and subject as random effect. RESULTS: Among 150 subjects, 17 reported diabetes, 12 reported beta-blocker use, 14 reported prior 24-hour opioid use, and 120 reported no comorbid conditions. PUAL declined in higher age categories (by 0.0307, P < 0.001), with diabetes (by 0.0481, P = 0.025), and with beta-blocker use (by 0.0616, P = 0.005). Opioid related PUAL decline was observed, but statistical significance varied by model. Among healthy subjects, no PUAL value fell within range indicating high likelihood of opioid toxicity based on previous data from healthy subjects undergoing opioid infusion. CONCLUSION: PUAL declined in higher age groups, diabetes and beta-blocker use, conditions associated with impaired autonomic function, and with opioid use but significance varied depending on the chosen model.

Mechanisms of visual working memory processing task-irrelevant information retrieved from visual long-term memory.

Visual working memory (VWM) can selectively filter task-irrelevant information from incoming visual stimuli. However, whether a similar filtering process applies to task-irrelevant information retrieved from visual long-term memory (VLTM) remains elusive. We assume a "resource-limited retrieval mechanism" in VWM in charge of the retrieval of irrelevant VLTM information. To make a comprehensive understanding of this mechanism, we conducted three experiments using both a VLTM learning task and a VWM task combined with pupillometry. The presence of a significant pupil light response (PLR) served as empirical evidence that VLTM information can indeed make its way into VWM. Notably, task-relevant VLTM information induced a sustained PLR, contrasting with the transient PLR observed for task-irrelevant VLTM information. Importantly, the transience of the PLR occurred under conditions of low VWM load, but this effect was absent under conditions of high load. Collectively, these results show that task-irrelevant VLTM information can enter VWM and then fade away only under conditions of low VWM load. This dynamic underscores the resource-limited retrieval mechanism within VWM, exerting control over the entry of VLTM information.

Pupil constriction by contrast for contrast.

The pupil is the eye's adjustable aperture. Fitzpatrick et al. find that visual contrast constricts the pupil, increasing contrast.1 This process improves behavioral performance. Its retinal origin has unorthodox elements, like interneurons that make connections in unusual locales and photoreceptive ganglion cells.

Illusory light drives pupil responses in primates.

In humans, the eye pupils respond to both physical light sensed by the retina and mental representations of light produced by the brain. Notably, our pupils constrict when a visual stimulus is illusorily perceived brighter, even if retinal illumination is constant. However, it remains unclear whether such perceptual penetrability of pupil responses is an epiphenomenon unique to humans or whether it represents an adaptive mechanism shared with other animals to anticipate variations in retinal illumination between successive eye fixations. To address this issue, we measured the pupil responses of both humans and macaque monkeys exposed to three chromatic versions (cyan, magenta, and yellow) of the Asahi brightness illusion. We found that the stimuli illusorily perceived brighter or darker trigger differential pupil responses that are very similar in macaques and human participants. Additionally, we show that this phenomenon exhibits an analogous cyan bias in both primate species. Beyond evincing the macaque monkey as a relevant model to study the perceptual penetrability of pupil responses, our results suggest that this phenomenon is tuned to ecological conditions because the exposure to a "bright cyan-bluish sky" may be associated with increased risks of dazzle and retinal damages.

Zonular fibre Insertion-to-Limbus Distance (ZLD): normative data to assess lens position and diagnose ectopia lentis.

PURPOSE: Subluxation of the crystalline lens (Ectopia Lentis, EL) can lead to significant visual impairment and serves as a diagnostic criterion for genetic disorders such as the Marfan syndrome. There is no established criterion to diagnose and quantify EL. We prospectively investigated the distance between the zonular fibre insertion and the limbus (ZLD) in healthy subjects as a parameter to assess the position of the lens, quantify EL and provide normative data. METHODS: This prospective, observational, cross-sectional study includes one-hundred-fifty eyes of 150 healthy participants (mean age 28 years, range 4-68). Pupils were dilated with tropicamide 0.5% and phenylephrine 2.5% eyedrops. ZLD was measured in mydriasis at the slit lamp as the distance between the most central visible insertions of the zonular fibres on the lens surface and the corneoscleral limbus. Vertical pupil diameter (PD) and refractive error were recorded. If zonular fibre insertions were not visible, the distance between limbus and the pupillary margin was recorded as ZLD. RESULTS: 145 right and 5 left eyes were examined. 93% of study subjects were Caucasian, 7% were Asian. In eyes with visible zonular fibre insertions (n = 76 eyes), ZLD was 1.30 ± 0.28 mm (mean ± SD, range 0.7-2.1) and PD was 8.79 ± 0.57 mm (7.5-9.8). In the remaining 74 eyes, ZLD was 1.38 ± 0.28 mm (0.7-2.1), and PD was 8.13 ± 0.58 mm (6.7-9.4). For all eyes, ZLD was 1.34 ± 0.29 mm (0.7-2.1), and PD was 8.47 ± 0.66 mm (6.7-9.8). Refractive error and sex did not significantly affect ZLD. Smaller PD and older age were associated with larger ZLD (P < 0.001 and P = 0.036, respectively). CONCLUSION: Average ZLD was 1.34 mm in eyes of healthy subjects. Older age correlated with larger ZLD. These normative data will aid in diagnosing and quantifying EL.

Altered pupil light and darkness reflex and eye-blink responses in late-life depression.

BACKGROUND: Late-life depression (LLD) is a prevalent neuropsychiatric disorder in the older population. While LLD exhibits high mortality rates, depressive symptoms in older adults are often masked by physical health conditions. In younger adults, depression is associated with deficits in pupil light reflex and eye blink rate, suggesting the potential use of these responses as biomarkers for LLD. METHODS: We conducted a study using video-based eye-tracking to investigate pupil and blink responses in LLD patients (n = 25), older (OLD) healthy controls (n = 29), and younger (YOUNG) healthy controls (n = 25). The aim was to determine whether there were alterations in pupil and blink responses in LLD compared to both OLD and YOUNG groups. RESULTS: LLD patients displayed significantly higher blink rates and dampened pupil constriction responses compared to OLD and YOUNG controls. While tonic pupil size in YOUNG differed from that of OLD, LLD patients did not exhibit a significant difference compared to OLD and YOUNG controls. GDS-15 scores in older adults correlated with light and darkness reflex response variability and blink rates. PHQ-15 scores showed a correlation with blink rates, while MoCA scores correlated with tonic pupil sizes. CONCLUSIONS: The findings demonstrate that LLD patients display altered pupil and blink behavior compared to OLD and YOUNG controls. These altered responses correlated differently with the severity of depressive, somatic, and cognitive symptoms, indicating their potential as objective biomarkers for LLD.

Ocular working memory signals are flexible to behavioral priority and subjective imagery strength.

The pupillary light response was long considered a brainstem reflex, outside of cognitive influence. However, newer findings indicate that pupil dilation (and eye movements) can reflect content held "in mind" with working memory (WM). These findings may reshape understanding of ocular and WM mechanisms, but it is unclear whether the signals are artifactual or functional to WM. Here, we ask whether peripheral and oculomotor WM signals are sensitive to the task-relevance or "attentional state" of WM content. During eye-tracking, human participants saw both dark and bright WM stimuli, then were retroactively cued to the item that would most likely be tested. Critically, we manipulated the attentional priority among items by varying the cue reliability across blocks. We confirmed previous findings that remembering darker items is associated with larger pupils (vs. brighter), and that gaze is biased toward cued item locations. Moreover, we discovered that pupil and eye movement responses were influenced differently by WM item relevance. Feature-specific pupillary effects emerged only for highly prioritized WM items but were eliminated when cues were less reliable, and pupil effects also increased with self-reported visual imagery strength. Conversely, gaze position consistently veered toward the cued item location, regardless of cue reliability. However, biased microsaccades occurred at a higher frequency when cues were more reliable, though only during a limited post-cue time window. Therefore, peripheral sensorimotor processing is sensitive to the task-relevance or functional state of internal WM content, but pupillary and eye movement WM signals show distinct profiles. These results highlight a potential role for early visual processing in maintaining multiple WM content dimensions.NEW & NOTEWORTHY Here, we found that working memory (WM)-driven ocular inflections-feature-specific pupillary and saccadic biases-were muted for memory items that were less behaviorally relevant. This work illustrates that functionally informative goal signals may extend as early as the sensorimotor periphery, that pupil size may be under more fine-grained control than originally thought, and that ocular signals carry multiple dimensions of cognitively relevant information.

Effects of driver's braking behavior by the real-time pedestrian scale warning system.

A driver warning system can improve pedestrian safety by providing drivers with alerts about potential hazards. Most driver warning systems have primarily focused on detecting the presence of pedestrians, without considering other factors, such as the pedestrian's gender and speed, and whether pedestrians are carrying luggage, that can affect driver braking behavior. Therefore, this study aims to investigate how driver braking behavior changes based on the information about the number of pedestrians in a crowd and examine if a developed warning system based on this information can induce safe braking behavior. For this purpose, an experiment scenario was conducted using a virtual reality-based driving simulator and an eye tracker. The collected driver data were analyzed using mixed ANOVA to derive meaningful conclusions. The research findings indicate that providing information about the number of pedestrians in a crowd has a positive impact on driver braking behavior, including deceleration, yielding intention, and attention. Particularly, It was found that in scenarios with a larger number of pedestrians, the Time to Collision (TTC) and distance to the crosswalk were increased by 12%, and the pupil diameter was increased by 9%. This research also verified the applicability of the proposed warning system in complex road environments, especially under conditions with poor visibility such as nighttime. The system was able to induce safe braking behavior even at night and exhibited consistent performance regardless of gender. In conclusion, considering various factors that influence driver behavior, this research provides a comprehensive understanding of the potential and effectiveness of a driver warning system based on information about the number of pedestrians in a crowd in complex road environments.

Auditory Challenges and Listening Effort in School-Age Children With Autism: Insights From Pupillary Dynamics During Speech-in-Noise Perception.

PURPOSE: This study aimed to investigate challenges in speech-in-noise (SiN) processing faced by school-age children with autism spectrum conditions (ASCs) and their impact on listening effort. METHOD: Participants, including 23 Mandarin-speaking children with ASCs and 19 age-matched neurotypical (NT) peers, underwent sentence recognition tests in both quiet and noisy conditions, with a speech-shaped steady-state noise masker presented at 0-dB signal-to-noise ratio in the noisy condition. Recognition accuracy rates and task-evoked pupil responses were compared to assess behavioral performance and listening effort during auditory tasks. RESULTS: No main effect of group was found on accuracy rates. Instead, significant effects emerged for autistic trait scores, listening conditions, and their interaction, indicating that higher trait scores were associated with poorer performance in noise. Pupillometric data revealed significantly larger and earlier peak dilations, along with more varied pupillary dynamics in the ASC group relative to the NT group, especially under noisy conditions. Importantly, the ASC group's peak dilation in quiet mirrored that of the NT group in noise. However, the ASC group consistently exhibited reduced mean dilations than the NT group. CONCLUSIONS: Pupillary responses suggest a different resource allocation pattern in ASCs: An initial sharper and larger dilation may signal an intense, narrowed resource allocation, likely linked to heightened arousal, engagement, and cognitive load, whereas a subsequent faster tail-off may indicate a greater decrease in resource availability and engagement, or a quicker release of arousal and cognitive load. The presence of noise further accentuates this pattern. This highlights the unique SiN processing challenges children with ASCs may face, underscoring the importance of a nuanced, individual-centric approach for interventions and support.

High-speed eye tracking based on a synchronized imaging mechanism by a dual-ring infrared lighting source.

It is a challenge for conventional monocular-camera single-light source eye-tracking methods to achieve high-speed eye tracking. In this work, a dual-ring infrared lighting source was designed to achieve bright and dark pupils in high speed. The eye-tracking method used a dual-ring infrared lighting source and synchronized triggers for the even and odd camera frames to capture bright and dark pupils. A pupillary corneal reflex was calculated by the center coordinates of the Purkinje spot and the pupil. A map function was established to map the relationship between the pupillary corneal reflex and gaze spots. The gaze coordinate was calculated based on the mapping function. The average detection time of each gaze spot was 3.76 ms.

Investigation of the behavior of tinnitus patients under varying listening conditions with simultaneous electroencephalography and pupillometry.

OBJECTIVE: This study aims to control all hearing thresholds, including extended high frequencies (EHFs), presents stimuli of varying difficulty levels, and measures electroencephalography (EEG) and pupillometry responses to determine whether listening difficulty in tinnitus patients is effort or fatigue-related. METHODS: Twenty-one chronic tinnitus patients and 26 matched healthy controls having normal pure-tone averages with symmetrical hearing thresholds were included. Subjects were evaluated with 0.125-20 kHz pure-tone audiometry, Montreal Cognitive Assessment Test (MoCA), Tinnitus Handicap Inventory (THI), EEG, and pupillometry. RESULTS: Pupil dilatation and EEG alpha power during the "encoding" phase of the presented sentence in tinnitus patients were less in all listening conditions (p < .05). Also, there was no statistically significant relationship between EEG and pupillometry components for all listening conditions and THI or MoCA (p > .05). CONCLUSION: EEG and pupillometry results under various listening conditions indicate potential listening effort in tinnitus patients even if all frequencies, including EHFs, are controlled. Also, we suggest that pupillometry should be interpreted with caution in autonomic nervous system-related conditions such as tinnitus.

The bigger your pupils, the better my comprehension: an ERP study of how pupil size and gaze of the speaker affect syntactic processing.

Gaze direction and pupil dilation play a critical role in communication and social interaction due to their ability to redirect and capture our attention and their relevance for emotional information. The present study aimed to explore whether the pupil size and gaze direction of the speaker affect language comprehension. Participants listened to sentences that could be correct or contain a syntactic anomaly, while the static face of a speaker was manipulated in terms of gaze direction (direct, averted) and pupil size (mydriasis, miosis). Left anterior negativity (LAN) and P600 linguistic event-related potential components were observed in response to syntactic anomalies across all conditions. The speaker's gaze did not impact syntactic comprehension. However, the amplitude of the LAN component for mydriasis (dilated pupil) was larger than for miosis (constricted pupil) condition. Larger pupils are generally associated with care, trust, interest, and attention, which might facilitate syntactic processing at early automatic stages. The result also supports the permeable and context-dependent nature of syntax. Previous studies also support an automatic nature of syntax (fast and efficient), which combined with the permeability to relevant sources of communicative information, such as pupil size and emotions, is highly adaptive for language comprehension and social interaction.

Beauty is in the iris: Constricted pupils (enlarged irises) enhance attractiveness.

Physical attractiveness profoundly affects a broad array of life experiences and outcomes, and the eyes are an important determinant of physical attractiveness. We investigated whether a particular feature of the eyes - pupil size - affects perceived attractiveness. We present competing theoretical predictions of whether dilated (larger) or constricted (smaller) pupils should appear more physically attractiveness. Youthful features tend to be attractive (i.e., neoteny), and pupil size decreases across the lifespan, so dilated (enlarged) pupils may be more attractive as a signal of youth. Alternatively, constricted (small) pupils may be more attractive because, by revealing more of the iris, they increase both color and brightness of the eyes. The present experiments demonstrate that people appear more attractive when their pupils are constricted (Experiments 1-3). This effect is equally large with black-and-white images, indicating that color per se is not necessary for the effect (Experiment 4). Rather, constricted pupils make eyes appear brighter, which in turn renders the face more attractive (Experiment 5), even when controlling for how colorful the eyes appear (Experiment 6). These results identify constricted pupils as a novel facial feature that enhances attractiveness.

Influencing Factors on Pupillary Light Responses as a Biomarker for Local Retinal Function in a Large Normative Cohort.

Purpose: Investigating influencing factors on the pupillary light response (PLR) as a biomarker for local retinal function by providing epidemiological data of a large normative collective and to establish a normative database for the evaluation of chromatic pupil campimetry (CPC). Methods: Demographic and ophthalmologic characteristics were captured and PLR parameters of 150 healthy participants (94 women) aged 18 to 79 years (median = 46 years) were measured with L-cone- and rod-favoring CPC protocols. Linear-mixed effects models were performed to determine factors influencing the PLR and optical coherence tomography (OCT) data were correlated with the pupillary function volume. Results: Relative maximal constriction amplitude (relMCA) and latency under L-cone- and rod-favoring stimulation were statistically significantly affected by the stimulus eccentricity (P < 0.0001, respectively). Iris color and gender did not affect relMCA or latency significantly; visual hemifield, season, and daytime showed only minor influence under few stimulus conditions. Age had a statistically significant effect on latency under rod-specific stimulation with a latency prolongation ≥60 years. Under photopic and scotopic conditions, baseline pupil diameter declined significantly with increasing age (P < 0.0001, respectively). Pupillary function volume and OCT data were not correlated relevantly. Conclusions: Stimulus eccentricity had the most relevant impact on relMCA and latency of the PLR during L-cone- and rod-favoring stimulation. Latency is prolonged ≥60 years under scotopic conditions. Considering the large study collective, a representative normative database for relMCA and latency as valid readout parameters for L-cone- and rod-favoring stimulation could be established. This further validates the usability of the PLR in CPC as a biomarker for local retinal function.