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Arquivos Brasileiros de Oftalmologia 2020The point of centration for refractive surgery is a theme of great importance that generates considerable discussion among specialists and surgeons in the field.... (Review)
Review
The point of centration for refractive surgery is a theme of great importance that generates considerable discussion among specialists and surgeons in the field. Notably, any changes in light can alter the size of the pupil, and the visual axis of the fixation line to the fovea is unique in each patient. A variety of options have been described in the literature with respect to centration in refractive surgery, and the results differ among these methods. No consensus has been established regarding the ideal refractive surgery technique for evaluation of centration in each patient that will yield a satisfactory surgical result.
Topics: Cornea; Fixation, Ocular; Humans; Keratomileusis, Laser In Situ; Lasers, Excimer; Pupil; Refraction, Ocular
PubMed: 31691730
DOI: 10.5935/0004-2749.20200014 -
Frontiers in Neural Circuits 2018Pupillometry has long been used as a measure of brain state. Changes in pupil diameter are thought to coincide with the activity of neuromodulators, including... (Review)
Review
Pupillometry has long been used as a measure of brain state. Changes in pupil diameter are thought to coincide with the activity of neuromodulators, including noradrenaline and acetylcholine, producing alterations in the brain state and corresponding changes in behavior. Here we review mechanisms underlying the control of pupil diameter and how these mechanisms are correlated with changes in cortical activity and the recruitment of neuromodulatory circuits.
Topics: Animals; Humans; Neocortex; Neurons; Organ Size; Pupil
PubMed: 29593504
DOI: 10.3389/fncir.2018.00021 -
Medical Science Monitor : International... Mar 2022Adie's pupil, also called tonic pupil, is mainly seen in young women. Most patients have unilateral eye involvement. The pupil of the affected side is significantly... (Review)
Review
Adie's pupil, also called tonic pupil, is mainly seen in young women. Most patients have unilateral eye involvement. The pupil of the affected side is significantly larger than that on the healthy side. The direct and indirect light reflection from the pupil on the affected side disappears. The pupil on the affected side is sensitive to low concentrations of pilocarpine. The pathogeneses of Adie's pupil are complex, some of which are insidious and lack corresponding specific diseases. Through a literature review, we found that Adie's pupil is mainly associated with infectious diseases, most commonly syphilis, followed by immune diseases and paraneoplastic syndromes. The ophthalmological symptoms and pupil abnormalities can disappear after active treatment of the primary disease. Pilocarpine can be used to treat ophthalmologic symptoms, such as blurred vision, for which patients might visit an ophthalmologist or neurologist. It is essential for clinicians to improve their understanding of the disease to avoid misdiagnosis. Differential diagnosis between Adie's pupil, oculomotor nerve palsy, anticholinergic drug overdose, Argyll-Robertson pupil, and congenital mydriasis need to be identified by the physician. Here, the clinical manifestations, pathogenesis, relationship between Adie's pupil and diseases, and differential diagnosis of Adie's pupil are reviewed.
Topics: Adie Syndrome; Diagnosis, Differential; Humans; Physicians; Pupil; Tonic Pupil
PubMed: 35304432
DOI: 10.12659/MSM.934657 -
The Journal of Neuroscience : the... May 2022Pupil size has been established as a versatile marker of noradrenergic and cholinergic neuromodulation, which has profound effects on neuronal processing, cognition, and...
Pupil size has been established as a versatile marker of noradrenergic and cholinergic neuromodulation, which has profound effects on neuronal processing, cognition, and behavior. However, little is known about the cortical control and effects of pupil-linked neuromodulation. Here, we show that pupil dynamics are tightly coupled to temporally, spectrally, and spatially specific modulations of local and large-scale cortical population activity in the human brain. We quantified the dynamics of band-limited cortical population activity in resting human subjects using magnetoencephalography and investigated how neural dynamics were linked to simultaneously recorded pupil dynamics. Our results show that pupil-linked neuromodulation does not merely affect cortical population activity in a stereotypical fashion. Instead, we identified three frontal, precentral, and occipitoparietal networks, in which local population activity with distinct spectral profiles in the theta, beta, and alpha bands temporally preceded and followed changes in pupil size. Furthermore, we found that amplitude coupling at ∼16 Hz in a large-scale frontoparietal network predicted pupil dynamics. Our results unravel network-specific spectral fingerprints of cortical neuromodulation in the human brain that likely reflect both the causes and effects of neuromodulation. Brain function is constantly affected by modulatory neurotransmitters. Pupil size has been established as a versatile marker of noradrenergic and cholinergic neuromodulation. However, because the cortical correlates of pupil dynamics are largely unknown, fundamental questions remain unresolved. Which cortical networks control pupil-linked neuromodulation? Does neuromodulation affect cortical activity in a stereotypical or region-specific fashion? To address this, we quantified the dynamics of cortical population activity in human subjects using magnetoencephalography. We found that pupil dynamics are coupled to highly specific modulations of local and large-scale cortical activity in the human brain. We identified four cortical networks with distinct spectral profiles that temporally predicted and followed pupil size dynamics. These effects likely reflect both the cortical control and effect of neuromodulation.
Topics: Brain; Cholinergic Agents; Cognition; Humans; Magnetoencephalography; Pupil
PubMed: 35361704
DOI: 10.1523/JNEUROSCI.1801-21.2022 -
International Ophthalmology Feb 2022To compare pupillary responses in patients with Coronavirus disease-2019 (COVID-19) during active infection and at 3rd months post-infection.
AIM
To compare pupillary responses in patients with Coronavirus disease-2019 (COVID-19) during active infection and at 3rd months post-infection.
METHODS
This study included 58 COVID-19 cases (mean age 47.23 ± 1.1 years). The scotopic, mesopic and photopic diameters were noted. Pupil diameters were noted at the 0, 1st, 2nd, 4th, 6th, 8th, and 10th seconds in reflex pupil dilation after the termination of a light. The average dilation speed was calculated at the 1st, 2nd, 4th, 6th, 8th, and 10th seconds. Pupil responses measured during COVID-19 infection and 3 months later were compared.
RESULTS
The mean scotopic and mesopic pupil diameter value of during COVID-19 infection was found lower than the 3rd month post-infection. (p = 0.001, p = 0.023; respectively). No statistically significant difference was found in the mean photopic pupil diameter and the mean pupil diameter at 0 s between measurements (p > 0.05, p = 0.734; respectively). The mean pupil diameter was significantly lower during COVID-19 infection at the 1st, 2nd, 4th, 6th, 8th and 10th seconds (p < 0.01, for each). The average dilation speed measurements at every second measured were lower in during COVID-19 infection than the 3rd months later (p = 0.001; p < 0.01 for each).
CONCLUSIONS
Pupil responses were found significantly different in COVID-19 cases when compared with the measurements taken three months later.
Topics: COVID-19; Color Vision; Humans; Middle Aged; Pupil; SARS-CoV-2
PubMed: 34613562
DOI: 10.1007/s10792-021-02053-z -
Sensors (Basel, Switzerland) Dec 2022In this paper, we present a framework for 3D gaze estimation intended to identify the user's focus of attention in a corneal imaging system. The framework uses a headset...
In this paper, we present a framework for 3D gaze estimation intended to identify the user's focus of attention in a corneal imaging system. The framework uses a headset that consists of three cameras, a scene camera and two eye cameras: an IR camera and an RGB camera. The IR camera is used to continuously and reliably track the pupil and the RGB camera is used to acquire corneal images of the same eye. Deep learning algorithms are trained to detect the pupil in IR and RGB images and to compute a per user 3D model of the eye in real time. Once the 3D model is built, the 3D gaze direction is computed starting from the eyeball center and passing through the pupil center to the outside world. This model can also be used to transform the pupil position detected in the IR image into its corresponding position in the RGB image and to detect the gaze direction in the corneal image. This technique circumvents the problem of pupil detection in RGB images, which is especially difficult and unreliable when the scene is reflected in the corneal images. In our approach, the auto-calibration process is transparent and unobtrusive. Users do not have to be instructed to look at specific objects to calibrate the eye tracker. They need only to act and gaze normally. The framework was evaluated in a user study in realistic settings and the results are promising. It achieved a very low 3D gaze error (2.12°) and very high accuracy in acquiring corneal images (intersection over union-IoU = 0.71). The framework may be used in a variety of real-world mobile scenarios (indoors, indoors near windows and outdoors) with high accuracy.
Topics: Fixation, Ocular; Eye Movements; Algorithms; Pupil; Cornea
PubMed: 36616978
DOI: 10.3390/s23010381 -
Clinical & Experimental Optometry May 2020To compare the static and dynamic pupillometry measurements in patients with pseudoexfoliation syndrome (PES), patients with pseudoexfoliation glaucoma (PEG) and...
BACKGROUND
To compare the static and dynamic pupillometry measurements in patients with pseudoexfoliation syndrome (PES), patients with pseudoexfoliation glaucoma (PEG) and age-matched healthy subjects using an automatic quantitative pupillometry system.
METHODS
This prospective, cross-sectional study consisted of 40 patients with PES, 30 patients with PEG and 43 control subjects. Static pupillometry measurements including scotopic pupil diameter, mesopic pupil diameter, low photopic pupil diameter, and high photopic pupil diameter were undertaken. Subsequently, dynamic pupillometry measurements including resting diameter, amplitude of pupil contraction, latency of pupil contraction, duration of pupil contraction, velocity of pupil contraction, latency of pupil dilation, duration of pupil dilation, and velocity of pupil dilation were undertaken. These measurements were compared between the groups.
RESULTS
The scotopic, mesopic, and low photopic pupil diameter values were statistically significantly lower in patients with PES and PEG compared with controls (p < 0.001). However, these parameters were similar between the patients with PES and PEG (p > 0.05). The mean values of high photopic pupil diameter were similar within all groups (p = 0.54). The amplitude of pupil contraction values of the patients with PEG was statistically significantly lower than the patients with PES and the controls (p < 0.05). Patients with PES also had significantly lower amplitude of pupil contraction values compared with controls (p < 0.001). Additionally, the velocity of pupil contraction values was statistically significantly higher in control subjects when compared to the patients with PES and PEG (p < 0.05).
CONCLUSION
This study demonstrated that accumulation of pseudoexfoliative material can cause alterations in static and dynamic pupillary characteristics and the progression from PES to PEG may be associated with reduced amplitude of pupil contraction values.
Topics: Aged; Aged, 80 and over; Cross-Sectional Studies; Disease Progression; Exfoliation Syndrome; Female; Glaucoma; Humans; Male; Middle Aged; Prospective Studies; Pupil
PubMed: 31364197
DOI: 10.1111/cxo.12945 -
Psychophysiology Jun 2018Pupil diameter is enhanced in a variety of emotional contexts, including viewing pictures, listening to sounds, and during threat of shock. In this study, we...
Pupil diameter is enhanced in a variety of emotional contexts, including viewing pictures, listening to sounds, and during threat of shock. In this study, we investigated pupil diameter changes during emotional imagery. Participants imagined scenes describing pleasant, unpleasant, or neutral events while pupil diameter was continuously recorded. Second by second changes in pupil diameter were analyzed to determine whether, and when, modulation of the pupil as a function of hedonic content is found. Results indicated a significant effect of hedonic content beginning shortly after script onset, with enhanced pupil diameter when imagining emotional (pleasant or unpleasant), compared to neutral, scenes. Pupil diameter during imagery covaried with rated emotional arousal, consistent with an interpretation that changes in pupil diameter during emotional imagery reflect sympathetic nervous system activity. Because emotional imagery is a key element in clinical assessment and treatment, pupil diameter could prove a useful index of emotional engagement in a variety of clinically pertinent contexts.
Topics: Adolescent; Adult; Emotions; Female; Humans; Imagination; Male; Pupil; Visual Perception; Young Adult
PubMed: 29266253
DOI: 10.1111/psyp.13050 -
Proceedings. Biological Sciences Sep 2019In conditions of constant illumination, the eye pupil diameter indexes the modulation of arousal state and responds to a large breadth of cognitive processes, including... (Review)
Review
In conditions of constant illumination, the eye pupil diameter indexes the modulation of arousal state and responds to a large breadth of cognitive processes, including mental effort, attention, surprise, decision processes, decision biases, value beliefs, uncertainty, volatility, exploitation/exploration trade-off, or learning rate. Here, I propose an information theoretic framework that has the potential to explain the ensemble of these findings as reflecting pupillary response to information processing. In short, updates of the brain's internal model, quantified formally as the Kullback-Leibler (KL) divergence between prior and posterior beliefs, would be the common denominator to all these instances of pupillary dilation to cognition. I show that stimulus presentation leads to pupillary response that is proportional to the amount of information the stimulus carries about itself and to the quantity of information it provides about other task variables. In the context of decision making, pupil dilation in relation to uncertainty is explained by the wandering of the evidence accumulation process, leading to large summed KL divergences. Finally, pupillary response to mental effort and variations in tonic pupil size are also formalized in terms of information theory. On the basis of this framework, I compare pupillary data from past studies to simple information-theoretic simulations of task designs and show good correspondance with data across studies. The present framework has the potential to unify the large set of results reported on pupillary dilation to cognition and to provide a theory to guide future research.
Topics: Arousal; Attention; Cognition; Decision Making; Humans; Learning; Photic Stimulation; Pupil; Uncertainty
PubMed: 31530143
DOI: 10.1098/rspb.2019.1593 -
Annals of Anatomy = Anatomischer... Jun 2024A reliable estimation of time since death can be important for the law enforcement authorities. The compound method encompassing supravital reactions such as the...
BACKGROUND
A reliable estimation of time since death can be important for the law enforcement authorities. The compound method encompassing supravital reactions such as the chemical excitability of the iris can be used to further narrow intervals estimated by temperature-based methods. Postmortem iris excitability was mostly assessed by parasympatholytic or parasympathomimetic substances. Little is known regarding sympathomimetic agents. The present study aims to describe the postmortem iris excitability using the sympathomimetic drug phenylephrine.
METHODS
Cadavers were included after body donors gave written informed consent during lifetime. Exclusion criteria were known eye disease, or a postmortem interval exceeding 26 hours. A pupillometer with a minimum measurement range of 0.5 mm was used to determine the horizontal pupil diameter before and 20 minutes after the application of phenylephrine. Increase in pupil diameter was labeled as positive reaction, unchanged pupil diameter was labeled as negative reaction, and decrease in pupil diameter was labeled as paradox reaction.
RESULTS
30 eyes from 16 cadavers (median age = 80.0; 9 males, 7 females) were examined. Initial pupil size was in median 3.5 mm (interquartile range [IQR]: 3.0-4.5 mm) and progressed to 4.0 mm (IQR: 3.5-5.0 mm) 20 minutes after drug instillation. The achieved pupil diameter difference comprised in median 0.5 mm (IQR: 0.0-1.0 mm). A positive reaction was observed in 21 cases. Negative reactions were observed in 5 cases and paradox reactions in 4 cases. Overall, there was a statistically significant difference in diameter between the initial and the reactive pupil (P = 0.0002).
CONCLUSION
Although relatively rarely used, sympathomimetic drugs seem to be eligible for chemical postmortem iris excitability. Currently, assessment of postmortem iris excitability usually only involves parasympatholytic and parasympathomimetic agents. The findings of the present study give a hint that the application of a third agent with a sympathomimetic mechanism of action could provide additional information. Further studies assessing such a triple approach in the compound method in comparison with the current gold standard for estimation of time since death are mandatory to ensure reliable results.
Topics: Humans; Male; Female; Iris; Phenylephrine; Postmortem Changes; Pupil; Aged, 80 and over; Cadaver; Aged; Sympathomimetics
PubMed: 38460860
DOI: 10.1016/j.aanat.2024.152240