Pupillary Light Reflex Research Articles

Association Between Pupil Light Reflex and Delirium in Adults With Traumatic Brain Injury: Preliminary Findings.

Association Between Pupil Light Reflex and Delirium in Adults With Traumatic Brain Injury: Preliminary Findings.

Pupil light reflex in young elite athletes: autonomic nervous system activity and viscoelastic properties.

Introduction: The pupil light reflex (photomotor reflex) has a duration of 3.5s and is a highly reproducible measurement. Conventionally, the autonomic nervous system (ANS) activity evaluated by this reflex does not consider the viscoelasticity of the iris muscles. This study aims to detect differences in reflex autonomic activity in a supine position with parameters derived from the Kelvin-Voigt viscoelastic model in two distinct groups of elite athletes. Method: Groups formed using a dendrogram analysis based on basal autonomic activity assessed with heart rate variability. Heart rate variability was measured, and the photomotor reflex was modeled. Results: The model showed a high degree of adjustment to the photomotor reflex (r2 = 0.99 ± 0.01). The impulse 3, an indicator of reflex sympathetic activity, revealed a significantly higher activity (ρ ≤ 0.05) in the [sympa/para]+ group compared to the [sympa/para]⁻ group. This result was further supported by a greater relative total redilation amplitude (ρ ≤ 0.05) and a shorter duration of 75% redilation (ρ ≤ 0.01). Finally, the relative total redilation amplitude exhibited a significant correlation with the linear stiffness constant (ρ ≤ 0.001) and the maximum redilation speed with restoring force (ρ ≤ 0.001). Discussion: These results indicate that (i) the photomotor reflex can detect an alteration of the reflex autonomic activity specific to each of the two branches of the ANS (ii) the viscoelastic properties of the iris muscles play a significant role in the energy storage-restitution mechanisms during the photomotor reflex. This approach could allow athletes to benefit from reduced time spent in the analysis of ANS activity, potentially making it an almost daily and automated process.

Detecting Alzheimer’s Patients using Features in Differential Waveforms of Pupil Light Reflex for Chromatic Stimuli

A procedure to detect irregular signal responses to pupil light reflex (PLR) was developed to detect Alzheimer’s Disease (AD) using a functional data analysis (FDA) technique and classification with an Elastic Net. In considering the differences in features of PLRs between AD and normal control (NC) participants, signals of summations and differentials between experimental conditions were analysed. The coefficient vectors for B-spline basis functions were introduced, and the number of basis was controlled for an optimised model. Model trained data was created using a data extension technique in order to enhance the number of participant observations. In the results, the required number of basis functions for differential signals is larger than the number for the their summation signals, and the features of differential signals contribute to classification performance.

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

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. Participants were 26 female subjects divided into 3 groups: emmetropic controls (E-CTRL, N = 12, mean age = 28.6 ± 7.8years) and 2 myopic (M-CTRL, N = 7, mean age = 25.7 ± 11.5years and MYP-26, N = 7, mean age = 28.3 ± 15.4years) 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 = 621nm) and blue (peak wavelength = 470nm) 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. 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. 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.

Early hypocoagulable state in traumatic brain injury patients: incidence, predisposing factors, and outcomes in a retrospective cohort study.

Coagulopathy development in traumatic brain injury (TBI) is among the significant complications that can negatively affect the clinical course and outcome of TBI patients. Timely identification of this complication is of utmost importance in the acute clinical setting. We reviewed TBI patients admitted to our trauma center from 2015 to 2021. Demographic data, mechanism of injury, findings on admission, imaging studies, procedures during hospitalization, and functional outcomes were gathered. INR with a cutoff of 1.3, platelet count less than 100 × 10⁹/L, or partial thromboplastin time greater than 40s were utilized as the markers of coagulopathy. A total of 4002 patients were included. Coagulopathy occurred in 38.1% of the patients. Age of the patients (Odds Ratio (OR) = 0.993, 95% Confidence Interval (CI) = 0.986-0.999, p = 0.028), systolic blood pressure (OR = 0.993, 95% CI = 0.989-0.998, p = 0.005), fibrinogen level (OR = 0.998, 95% CI = 0.996-0.999, p < 0.001), and hemoglobin level (OR = 0.886, 95% CI = 0.839-0.936, p < 0.001) were independently associated with coagulopathy. Furthermore, coagulopathy was independently associated with higher mortality rates and longer ICU stays. Coagulopathy had the most substantial effect on mortality of TBI patients (OR = 2.6, 95% CI = 2.1-3.3, p < 0.001), compared to other admission clinical characteristics independently associated with mortality such as fixed pupillary light reflex (OR = 1.8, 95% CI = 1.5-2.4, p < 0.001), GCS (OR = 0.91, 95% CI = 0.88-0.94, p < 0.001), and hemoglobin level (OR = 0.93, 95% CI = 0.88-0.98, p = 0.004). Early coagulopathy in TBI patients can lead to higher mortality rates. Future studies are needed to prove that early detection and correction of coagulopathy and modifiable risk factors may help improve outcomes of TBI patients.

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

BackgroundLate-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.MethodsWe 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.ResultsLLD 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.ConclusionsThe 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.

Heart rate variability for neuro-prognostication after CA: Insight from the Parisian registry

BackgroundHypoxic ischemic brain injury (HIBI) induced by cardiac arrest (CA) seems to predominate in cortical areas and to a lesser extent in the brainstem. These regions play key roles in modulating the activity of the autonomic nervous system (ANS), that can be assessed through analyses of heart rate variability (HRV). The objective was to evaluate the prognostic value of various HRV parameters to predict neurological outcome after CA. MethodsRetrospective monocentric study assessing the prognostic value of HRV markers and their association with HIBI severity. Patients admitted for CA who underwent EEG for persistent coma after CA were included. HRV markers were computed from 5 min signal of the ECG lead of the EEG recording. HRV indices were calculated in the time-, frequency-, and non-linear domains. Frequency-domain analyses differentiated very low frequency (VLF 0.003–0.04 Hz), low frequency (LF 0.04–0.15 Hz), high frequency (HF 0.15–0.4 Hz), and LF/HF ratio. HRV indices were compared to other prognostic markers: pupillary light reflex, EEG, N20 on somatosensory evoked potentials (SSEP) and biomarkers (neuron specific enolase-NSE). Neurological outcome at 3 months was defined as unfavorable in case of best CPC 3–4-5. ResultsBetween 2007 and 2021, 199 patients were included. Patients were predominantly male (64%), with a median age of 60 [48.9–71.7] years. 76% were out-of-hospital CA, and 30% had an initial shockable rhythm. Neurological outcome was unfavorable in 73%. Compared to poor outcome, patients with a good outcome had higher VLF (0.21 vs 0.09 ms2/Hz, p < 0.01), LF (0.07 vs 0.04 ms2/Hz, p = 0.003), and higher LF/HF ratio (2.01 vs 1.01, p = 0.008). Several non-linear domain indices were also higher in the good outcome group, such as SD2 (15.1 vs 10.2, p = 0.016) and DFA α1 (1.03 vs 0.78, p = 0.002). These indices also differed depending on the severity of EEG pattern and abolition of pupillary light reflex. These time–frequency and non-linear domains HRV parameters were predictive of poor neurological outcome, with high specificity despite a low sensitivity. ConclusionIn comatose patients after CA, some HRV markers appear to be associated with unfavorable outcome, EEG severity and PLR abolition, although the sensitivity of these HRV markers remains limited.

Quantitative Pupillometry Predicts Return to Play and Tracks the Clinical Evolution of Mild Traumatic Brain Injury in US Military Academy Cadets: A Military Traumatic Brain Injury Initiative Study.

The objective of this study was to determine the utility of the pupillary light reflex use as a biomarker of mild traumatic brain injury (mTBI). This prospective cohort study was conducted at The US Military Academy at West Point. Cadets underwent a standard battery of tests including Balance Error Scoring System, Sports Concussion Assessment Tool Fifth Edition Symptom Survey, Standard Assessment of Concussion, and measure of pupillary responses. Cadets who sustained an mTBI during training events or sports were evaluated with the same battery of tests and pupillometry within 48 hours of the injury (T1), at the initiation of a graded return to activity protocol (T2), and at unrestricted return to activity (T3). Pupillary light reflex metrics were obtained in 1300 cadets at baseline. During the study period, 68 cadets sustained mTBIs. At T1 (<48 hours), cadets manifested significant postconcussion symptoms (Sports Concussion Assessment Tool Fifth Edition P < .001), and they had decreased cognitive performance (Standardized Assessment of Concussion P < .001) and higher balance error scores (Balance Error Scoring System P < .001) in comparison with their baseline assessment (T0). The clinical parameters showed normalization at time points T2 and T3. The pupillary responses demonstrated a pattern of significant change that returned to normal for several measures, including the difference between the constricted and initial pupillary diameter (T1 P < .001, T2 P < .05), dilation velocity (T1 P < .01, T2 P < .001), and percent of pupillary constriction (T1 P < .05). In addition, a combination of dilation velocity and maximum constriction velocity demonstrates moderate prediction ability regarding who can return to duty before or after 21 days (area under the curve = 0.71, 95% CI [0.56-0.86]). This study's findings indicate that quantitative pupillometry has the potential to assist with injury identification and prediction of symptom severity and duration.

Automated Pupillometry Is Able to Discriminate Patients with Acute Stroke from Healthy Subjects: An Observational, Cross-Sectional Study.

Automated pupillometry (AP) is a handheld, non-invasive tool that is able to assess pupillary light reflex dynamics and is useful for the detection of intracranial hypertension. Limited evidence is available on acute ischemic stroke (AIS) patients. The primary objective was to evaluate the ability of AP to discriminate AIS patients from healthy subjects (HS). Secondly, we aimed to compute a predictive score for AIS diagnosis based on clinical, demographic, and AP variables. We included 200 consecutive patients admitted to a comprehensive stroke center who underwent AP assessment through NPi-200 (NeurOptics®) within 72 h of stroke onset and 200 HS. The mean values of AP parameters and the absolute differences between the AP parameters of the two eyes were considered in the analyses. Predictors of stroke diagnosis were identified through univariate and multivariate logistic regressions; we then computed a nomogram based on each variable's β coefficient. Finally, we developed a web app capable of displaying the probability of stroke diagnosis based on the predictive algorithm. A high percentage of pupil constriction (CH, p < 0.001), a low constriction velocity (CV, p = 0.002), and high differences between these two parameters (p = 0.036 and p = 0.004, respectively) were independent predictors of AIS. The highest contribution in the predictive score was provided by CH, the Neurological Pupil Index, CV, and CV absolute difference, disclosing the important role of AP in the discrimination of stroke patients. The results of our study suggest that AP parameters, and in particular, those concerning pupillary constriction, may be useful for the early diagnosis of AIS.

The role of retinal irradiance estimates in melanopsin-driven retinal responsivity: a reanalysis of the post-illumination pupil response in seasonal affective disorder.

To isolate melanopsin contributions to retinal sensitivity measured by the post-illumination pupil response (PIPR), controlling for individual differences in non-melanopsin contributions including retinal irradiance is required. When methodologies to negate such differences present barriers, statistical controls have included age, baseline diameter, iris pigmentation, and circadian time of testing. Alternatively, the pupil light reflex (PLR) and calculations estimating retinal irradiance both reflect retinal irradiance, while the PLR also reflects downstream pathways. We reanalyzed data from an observational, correlational study comparing the PIPR across seasons in seasonal affective disorder (SAD) and controls. The PIPR was measured in 47 adults in Pittsburgh, Pennsylvania (25 SAD) over 50 seconds after 1 second of red and blue stimuli of 15.3 log photons/cm2/s. The PLR was within 1 second while PIPR was averaged over 10-40 seconds post-stimulus. Two raters ranked iris pigmentation using a published scale. We evaluated model fit using Akaike's Information Criterion (AIC) across different covariate sets. The best-fitting models included either estimated retinal irradiance or PLR, and circadian time of testing. The PLR is collected contemporaneously in PIPR studies and is an individually specific measure of nonspecific effects, while being minimally burdensome. This work extends the prior publication by introducing theoretically grounded covariates that improved analytic model fits based on AIC specific to the present methods and sample. Such quantitative methods could be helpful in studies which must balance participant and researcher burden against tighter methodological controls of individual differences in retinal irradiance.

Immediate effect of Kaki Mudra on pupillary light reflex among healthy individuals – A study protocol of a Randomized control trial

Abstract Background Kaki Mudra is a yogic gesture that involves nasikagara drishti focusing on the nose tip without the eyes blinking and pursing the lips, which form beaks during inhalation, and exhaling slowly through the nose. However, there is a lack of evidence on the impact of kaki mudra on cardiovascular changes and autonomic function using pupillary light reflex (PLR). Methods A randomized control study design will be adopted for this study with 80 healthy participants with more than 18 years of age, will be recruited. Subjects will be randomly divided into the study (n = 40) and control groups (n = 40). The study group will be advised to practice Kaki Mudra for 20 min, whereas the control group will be asked to relax in sitting posture for 20 min. Results The baseline and post-assessment will be immediately evaluated for all the individuals; five leads to ECG for heart rate variability (HRV) and dynamic pupillometry for PLR. Discussion The immediate effect of kaki mudra is an effective and simple technique that might improve HRV and PLR variable, which may improve overall health and enhance parasympathetic dominance among healthy participants. The study is prospectively registered in the Clinical Trial Registry of India (CTRI/2024/05/067289).

Early Tracheostomy versus Late Tracheostomy in Patients with Moderate-to-Severe Traumatic Brain Injury.

Objective The aim of this article was to study the impact of early versus late tracheostomy on clinical outcomes of moderate-to-severe traumatic brain injury (TBI). Materials and Methods A retrospective cross-sectional study was conducted in the Neurosurgery Department, Mayo Hospital, Lahore, in which a sample size of 50 cases was calculated over a period of 6 months from January 1, 2022, to June 30, 2022. The included cases were patients who suffered from moderate-to-severe TBI, isolated TBI, needed elective ventilation, required intensive care unit (ICU) admission during their hospital stay, and were between the ages of 18 and 65 years. All the rest were excluded. A structured proforma was used by the physician to collect data after the informed consent of the patient. The results were computed and analyzed statistically using Statistical Package for Social Sciences , version 26. Results The median age of patients was 40 (interquartile [IQ] range 34) years and were predominantly male (72%). The most common mode of injury was road traffic accidents (58%). The median Glasgow Coma Scale (GCS) score at arrival was 8 (IQ range 6) and the most common pupillary light reflex at presentation was bilaterally equally responsive to light (68%). Neurologic deficits were mostly absent or cannot be assessed on presentation (86%) and in 38% of the cases multiple findings were noted on computed tomography (CT) scan while among single findings seen on CT scan, subdural hematoma was the most common (22%). Multiple regression analysis was done through two separate models using age, gender, mode of injury, presenting GCS score, number of CT-scan findings, number of days after endotracheal intubation after which tracheostomy was done, and the timing of tracheostomy (early vs. late) as predictors, and a significant relationship was noted between the timing of tracheostomy (early vs. late) and GCS at discharge ( p = 0.001) as well as extended Glasgow Outcome Score (GOS) at discharge ( p = 0.013). Conclusion This study suggests that moderate-to-severe TBIs are most common in middle-aged males and mostly involve road traffic accidents. In most cases, multiple CT-scan findings are seen as compared with a single predominant finding. In such patients, early tracheostomy is superior to late tracheostomy as it results in significantly better GCS and GOS scores at discharge as well as a decreased duration of mechanical ventilation and ICU stay.

Association Between Pupil Light Reflex and Delirium in Adults With Traumatic Brain Injury: Preliminary Findings.

BACKGROUND: Delirium is a common neurological complication in patients admitted to the intensive care unit (ICU) after moderate to severe traumatic brain injury (TBI). Although current clinical guidelines prioritize delirium prevention, no specific tool is tailored to detect early signs of delirium in TBI patients. This preliminary 2-phase observational study investigated the correlation between the pupillary light reflex (PLR), measured with a pupillometer during mechanical ventilation, and the development of postextubation delirium in TBI patients. METHODS: A convenience sample of 26 adults with moderate to severe TBI under mechanical ventilation was recruited during their ICU stay. In phase I, PLR measurements were performed in the first 3 days of ICU admission using automated infrared pupillometry. In phase II, 2 raters independently extracted delirium data in the 72 hours post extubation period from medical records. Delirium was confirmed with a documented medical diagnosis. Point-biserial correlations ( rpb ) were used to examine the association between PLR scores and the presence of postextubation delirium. Student t tests were also performed to compare mean PLR scores between patients with and without delirium. RESULTS: Ten TBI patients (38%) were diagnosed with postextubation delirium, whereas 16 (62%) were not. Significant correlations between delirium and 2 PLR variables were found: pupil constriction percentage ( rpb (24) = -0.526, P = .006) and constriction velocity ( rpb (24) = -0.485, P = .012). The t test also revealed a significant difference in constriction percentage and velocity scores between TBI patients with and without delirium ( P ≤ .01). CONCLUSION: Our findings suggest that the use of pupillometry in the first 3 days of mechanical ventilation during an ICU stay may help identify TBI patients at risk for delirium after extubation. Although further research is necessary to support its validity, this technological tool may enable ICU nurses to better screen TBI patients for delirium and prevent its development.

Neuro-ophthalmic Tests for Assessment of Vision Before and After Phacoemulsification in Cataractous Dogs

Background: The aim of current study was to assess pre and post-operative vision status through neuro-ophthalmic examination of 24 canine eyes after phacoemulsification with implantation of different acrylic intra ocular lenses. Methods: The study was conducted on 24 canine eyes. Preoperatively, detailed neuro-ophthalmic tests viz. Menace response, Pupillary light reflex (PLR), Obstacle Course and Moving object (cotton ball) were conducted for assessment of vision due to cataract and to exclude other ocular pathologies. Dogs were divided in four groups with 6 eyes in each group and subjected to phacoemulsification procedure for removal of cataractous lens and implanted with square edge or round edge, hydrophilic or hydrophobic intra ocular lenses (IOL). Post operatively, aforementioned neuro-ophthalmic tests were conducted on 3, 7 and 15 days and scores were given and comparatively analysed for vision acuity. Result: Preoperatively, neuro-opthalmic tests indicated poor and absent vision in eyes affected with various stages of cataract. Post operatively, the visual outcome in dogs of all treatment groups were assessed from the scores obtained in various neuro-ophthalmic tests. Neuro-ophthalmic evaluation revealed restoration of vision in 50% dogs in group I, II, IV and in 66.66% dogs of group III on day 15 after phacoemulsification and intraocular lens (IOL) implantation. It was concluded that neuro-ophthalmic tests are useful and mandatory protocols for pre and post-operative vision assessment in dogs with cataract.

Recovery of Oculomotor Nerve Palsy After Surgical and Endovascular Repair of Unruptured Internal Carotid-Posterior Communicating Artery Aneurysms

Unruptured posterior communicating artery (Pcom) aneurysms cause oculomotor nerve palsy (ONP). However, the time course of recovery after aneurysm repair remains unclear. We aimed to evaluate the ONP course after clipping and coiling for unruptured Pcom aneurysms. We retrospectively reviewed the medical records of 25 consecutive patients with ONP due to unruptured Pcom aneurysms, undergoing aneurysm repair at our institution during 2010-2022. We analyzed the clinical data, angiographic results, and surgical complications. The time to ONP recovery was evaluated using the Kaplan-Meier method. This study included 14 patients undergoing surgical clipping and 11 undergoing endovascular coiling. The two groups exhibited no significant differences in complete or partial ONP percentage or in symptom presentation (ptosis, diplopia, ocular paralysis, pupillary light reflex disorder, or mydriasis). All patients achieved complete or partial recovery during the follow-up period. The median time to partial or complete improvement in ONP was significantly shorter for clipping compared to coiling (2days vs. 33days; P= 0.009). Preoperative partial and complete ONP were stratified; clipping improved significantly earlier than coiling in the complete ONP group (P= 0.010). In the early treatment group (based on the median duration of treatment), clipping resulted in earlier improvement than coiling (P= 0.014). In the small aneurysm group (based on the median of the aneurysm maximum diameter), clipping resulted in earlier improvement than coiling (P= 0.005). In ONP caused by an unruptured Pcom aneurysm, clipping may provide faster recovery than coiling, particularly in cases of early onset, complete palsy, and small aneurysms.

Prognostic factors and clinical features of rhino-orbital-mucormycosis cases: an update for patient and visual survivals.

To determine the frequency of patients' vision survival and prognostic factors and evaluate clinical features in rhino-orbital mucormycosis. Forty-three eyes of 43 patients followed up with orbital mucormycosis infections were included in the study. Demographic characteristics of the patients, symptoms at admission, ophthalmologic and non-ophthalmologic examination findings, clinical findings during follow-up, medical and surgical procedures, and complications were recorded. Patient survival was determined by assessing the incidence of mortality, and vision survival was defined as achieving a final visual acuity of at least light perception. Twenty-seven (62.8%) patients were male, and 16 (37.2%) were female. When the underlying disease status of the patients was examined, it was observed that all patients had an underlying disease and diabetes constituted the majority (65.2%). Periorbital swelling (69.8%) and ophthalmoplegia (53.5%) were the most common symptoms and findings at the admission of patients with mucormycosis infection. The disease resulted in death in 22 (51.2%) patients. The presence of fever and shorter duration of antifungal therapy were associated with lower patient survival. Exenteration surgery was not found to be associated with the survival of the patients. Frozen eye, loss of pupillary light reflex, and development of central retinal artery occlusion were associated with lower vision survival. This study presents one of the most extensive patient series in the literature on rhino-orbital mucormycosis. Knowing the patients' symptoms at the time of admission and the clinical findings during the infection process will increase awareness about the disease.

Management of Eye Protrusion in Cats with Acute Trauma

Preventing permanent vision loss and damage to the bulbus oculi in cases of proptosis, which is very important in small animal eye emergencies, and protecting the anatomical structures of the eye. Early intervention is important for protection. In this study, patients with proptosis who had experienced acute trauma. It was aimed to report the treatment and results of cats. Proptosis was diagnosed in 11 of 96 cats (11.45%) who presented to eye emergencies. On examination, all cats had eye. It was determined that the edges of the eyelids were not visible, the bulbus oculi was muffled, the bulbus oculi was hyperemic and edematous, there was a pupillary light reflex in 9 cases, and there was no pupillary light reflex in 2 cases. In the treatment, enucleation was applied in 2 cases, canthotomy and temporary blepharraphy were applied in 3 cases, and temporary blepharraphy was applied in 6 cases. It was determined that there were no postoperative complications in all cases and visual function was observed in all cases except for those who underwent enucleation. As a result, urgent intervention is important to protect the anatomical structures of the eye and maintain visual function in proptosis. The results obtained from this study are satisfactory for cats and their caregivers.

Normal baseline cardiac autonomic function and increased pupillary parasympathetic tone in patients with vasovagal syncope.

It is controversial whether people with vasovagal syncope (VVS) have abnormal autonomic responses at baseline and whether specific diagnostic manoeuvres have a diagnostic value. We investigated whether the pupillary light reflex and cardiac autonomic tests can be used to identify autonomic dysfunction in volunteers with a medical history of VVS. The study groups included 128 healthy volunteers, of whom 31 reported a history of typical VVS. The right pupil was evaluated using an automated, commercial infra-red pupillometer under strict conditions. In addition to miosis and mydriasis kinetics, pupil diameters were measured. Heart rate variability at rest and heart rate changes to standing were quantified with high-resolution electrocardiography and designated software. The demographic and clinical characteristics of both groups were statistically similar. Average constriction velocity (ACV) was significantly higher in VVS patients following a univariate analysis (3.83 ± 0.59vs. 3.56 ± 0.73 mm/s, p = 0.042) and after correcting for potential confounders (p = 0.049). All other pupillometric and heart rate indices were comparable between groups. Patients with a history of VVS depict pupillary parasympathetic overactivity in response to light stimuli, manifested as increased ACV. The prognostic implications of this finding and the significance of using this simple clinical tool to identify patients who are at risk for developing frequent episodes of VVS or physical injuries following a syncope merits further study.

0024 Measuring Melanopsin-driven Retinal Responses in Sleep and Circadian Health: Performance of the Pupil Light Reflex

0024 Measuring Melanopsin-driven Retinal Responses in Sleep and Circadian Health: Performance of the Pupil Light Reflex

Machine learning approach for ambient-light-corrected parameters and the Pupil Reactivity (PuRe) score in smartphone-based pupillometry.

The pupillary light reflex (PLR) is the constriction of the pupil in response to light. The PLR in response to a pulse of light follows a complex waveform that can be characterized by several parameters. It is a sensitive marker of acute neurological deterioration, but is also sensitive to the background illumination in the environment in which it is measured. To detect a pathological change in the PLR, it is therefore necessary to separate the contributions of neuro-ophthalmic factors from ambient illumination. Illumination varies over several orders of magnitude and is difficult to control due to diurnal, seasonal, and location variations. We assessed the sensitivity of seven PLR parameters to differences in ambient light, using a smartphone-based pupillometer (AI Pupillometer, Solvemed Inc.). Nine subjects underwent 345 measurements in ambient conditions ranging from complete darkness (<5 lx) to bright lighting (≲10,000 lx). Lighting most strongly affected the initial pupil size, constriction amplitude, and velocity. Nonlinear models were fitted to find the correction function that maximally stabilized PLR parameters across different ambient light levels. Next, we demonstrated that the lighting-corrected parameters still discriminated reactive from unreactive pupils. Ten patients underwent PLR testing in an ophthalmology outpatient clinic setting following the administration of tropicamide eye drops, which rendered the pupils unreactive. The parameters corrected for lighting were combined as predictors in a machine learning model to produce a scalar value, the Pupil Reactivity (PuRe) score, which quantifies Pupil Reactivity on a scale 0-5 (0, non-reactive pupil; 0-3, abnormal/"sluggish" response; 3-5, normal/brisk response). The score discriminated unreactive pupils with 100% accuracy and was stable under changes in ambient illumination across four orders of magnitude. This is the first time that a correction method has been proposed to effectively mitigate the confounding influence of ambient light on PLR measurements, which could improve the reliability of pupillometric parameters both in pre-hospital and inpatient care settings. In particular, the PuRe score offers a robust measure of Pupil Reactivity directly applicable to clinical practice. Importantly, the formulae behind the score are openly available for the benefit of the clinical research community.