Jacobi-Fourier phase masks as ophthalmic elements to correct presbyopia.

PURPOSE: Investigations into the correction of presbyopia have considered lens design, clinical implications and the development of objective metrics such as the visual Strehl ratio. This study investigated the Jacobi-Fourier phase mask as an ophthalmic element in the correction of presbyopia. The goal was to develop a contact or intraocular lens whose performance was largely insensitive to changes in pupil diameter. METHODS: Numerical simulations based on Fourier optics were performed to evaluate three different Jacobi-Fourier polynomials, with the aim of providing a range of clear vision (1 Dioptre (D)). Performance was evaluated for three pupil sizes (6, 4 and 2 mm), while polychromatic images were simulated using three different wavelengths (656.3, 587.6 and 486.1 nm). The Neural Transfer function was included in the simulation. To validate the method and results, we used the Visual Strehl combined objective metric (VSCombined) currently used in visual optics. This metric gives more weight to the phase transfer function and is more suitable for non-symmetrical phase functions. RESULTS: Numerical validation showed the suitability of the Jacobi-Fourier phase masks for extending the range of clear vision of presbyopic eyes, providing a visual acuity of at least 0.10 logMAR (6/7.5 Snellen) at all distances between 1 and 6 m. The results show a range of clear vision of 1D was not affected by changes in pupil size, an increase in retinal image contrast accompanied by image artefact reduction by increasing the radial order of the Jacobi-Fourier phase mask and a reduction of wavelength dependence of the retinal images. These results are supported by simulated images and the objective criterion VSCombined. CONCLUSIONS: The use of Jacobi-Fourier phase masks as ophthalmic elements for presbyopic correction show promising results, with a good range of clear vision and reduced dependence on pupil size and chromatic aberration.

Pistol shooting performance under pressure: Longitudinal changes in gaze behavior of male and female Army cadets.

We found evidence that Army cadets improved their gaze behavior and performance across time under high and low pressure in a shooting task. The purpose of the study was to determine if male and female cadets developed an optimal quiet eye (QE) onset, a longer QE duration, and decreased pupil diameter variability (PDV) over time under low (LP) and high pressure (HP) conditions. The study was carried out over four sessions, with intervals of 4.5 months. During each session, 16 men and 12 women, first-year cadets of The Brazilian Army Academy, performed ten pistol shots under counterbalanced LP and HP conditions. The cadets shot in the upright position and wore an eye-tracker. Shooting accuracy improved and did not differ for men and women in the LP condition, however during HP the women performed more poorly than the men in session 1 but improved to a level similar to the men in session 4. QE duration Pre (aiming) did not differ during LP, while during HP QE Post (execution) increased across the session for men and women. QE onset 2 (execution) occurred earlier for the men than women during LP, while during HP the women improved to a level similar to the men in sessions 3 and 4. PDV declined across sessions for men and women with the lowest values in sessions 3 and 4. The findings are discussed within social facilitation theory, which states the context of training affects the rate at which improvements in motor skills occur. The results show that women cadets can improve their shooting performance, quiet eye duration, quiet eye onset and pupil diameter variability to a level similar to men if three to four LP and HP training sessions are scheduled across approximately 12-18 months.

Pupil size change in agricultural workers exposed to pesticides.

CLINICAL RELEVANCE: Pupil size evaluation using clinical examination may be important for detecting and monitoring individuals at risk of neurotoxic effects from chemical exposure, as it may enable early intervention and the implementation of preventive measures. BACKGROUND: This work aimed to investigate the association between pesticide exposure and pupil size. Pupil size is regulated by muscarinic and nicotinic receptors, and it is well-established that common pesticide chemicals disrupt this regulation. METHODS: Twenty agricultural workers exposed to pesticides, and twenty participants not exposed, underwent visual screening, and pupil size evaluation under mesopic and photopic conditions. Additionally, signs of neurotoxicity and pesticide exposure in both groups were evaluated using the modified version of the neurotoxic symptoms questionnaire (Q16) and measuring cholinesterase (AChE) levels in blood, respectively. RESULTS: Agricultural workers exposed to pesticides had a score indicating medium-high level of neurotoxicity (49.85 (SD ± 8.94)) which was significantly higher (t (36) = 7.659, p ≤ 0.0001) than non-exposed participants who had low levels of neurotoxicity (27.25 SD ± 8.86). There was a significant difference in pupil size (mm) under mesopic (t (19) 4.42 p = 0.003) and scotopic (t (19) 4.63, p = 0.0002) conditions between the two groups. Additionally, there was a significant difference in AChE blood levels (t (19) 2.94 p = 0.008) between exposed and non-exposed participants, indicating that exposed workers had low levels of this enzyme (average exposed group 3381 U/L (SD ± 1306)) compared to the non-exposed group (average non-exposed group 4765 U/L (SD ± 1300)). A significant negative correlation between AChE levels, years of exposure, and pupil size was found. The latter finding importantly showed that smaller pupils are associated with the accumulation of acetylcholine or a decrease in the activity of the enzyme AChE. CONCLUSION: Pupil size of agricultural workers exposed to pesticides can be abnormal and is associated with neurotoxicity as indicated by symptomatology and cholinesterase levels. Evaluation of pupil size may be useful for clinically detecting neurotoxicity.

Measurement of the visual axis through two different methods: quantification and differences for measuring chord μ / Medição do eixo visual através de dois métodos diferentes: quantificação e diferenças para medição da corda μ

ABSTRACT Purpose: To compare the differences between the apparent and actual chord μ. Methods: In this prospective, comparative, non-randomized, and non-interventional study, imaging examinations using Pentacam and the HD Analyzer were performed in the same room under the same scotopic conditions. The inclusion criteria were patients aged 21-71 years, able to provide informed consent, myopia up to 4D, and anterior topographic astigmatism up to 1D. Patients using contact lenses, those with previous eye diseases or surgeries, corneal opacities, corneal tomographic changes, or suspected keratoconus were excluded. Results: Altogether, 116 eyes of 58 patients were analyzed. The patients' mean age was 30.69 (±7.85) years. In the correlation analyses, Pearson's correlation coefficient of 0.647 indicates a moderate positive linear relationship between apparent and actual chord μ. The mean actual and apparent chord μ were 226.21 ± 128.53 and 278.66 ± 123.90 μm, respectively, with a mean difference of 52.45 μm (p=0.01). The analysis of mean pupillary diameter resulted in 5.76 mm using the HD Analyzer and 3.31 mm using the Pentacam. Conclusions: We found a correlation between the two measurement devices, and even though we found considerable differences, both can be used in daily practice. Given their differences, we should respect their peculiarities as well.

RESUMO Objetivo: Comparar as diferenças entre a chord aparente μ e o chord real μ. Métodos: Estudo prospectivo, comparativo, não randomizado e não intervencionista. Os exames de imagem (Pentacam e HD Analyzer) foram realizados na mesma sala e nas mesmas condições escotópicas. Os critérios de inclusão foram idade de 21 a 71 anos; compreensão do termo de consentimento; miopia até 4D e astigmatismo topográfico anterior até 1D. Os critérios de exclusão foram usuários de lentes de contato; pacientes com doenças oculares prévias ou cirurgias; opacidades da córnea; a presença de alterações tomográficas da córnea ou suspeita de ceratocone. Resultados: Em nosso estudo foram analisados 116 olhos de 58 pacientes. A média de idade foi de 30,69 anos (± 7,85). Análises de correlação foram desenvolvidas e o coeficiente de correlação de Pearson (0,647) indica uma relação linear positiva moderada entre as variáveis. A média do chord μ real foi 226,21 ± 128,53 μm e a média do chord μ média foi 278,66 ± 123,90 μm, com diferença média de 52,45 μm (p=0,01). A análise do diâmetro pupilar médio apresentou: 5,76mm no HD Analyzer e 3,31mm no Pentacam. Conclusões: Entendemos a existência de uma diferença significativa entre os métodos e assim a medida de ambos os dispositivos com base em princípios diferentes devemos respeitar suas peculiaridades. Como encontramos correlação entre as duas medidas, acreditamos que ambas podem ser utilizadas na prática diária.

Bilateral tonic pupil during a migraine attack: a case report / Pupila tônica bilateral durante crise de enxaqueca: relato de caso

INTRODUCTION:Tonic pupil or Adie's pupil occurs due to parasympathetic denervation, and it is characterized by mydriasis with little or no response to light, with pupillary contraction to accommodation. It is caused by eye pathologies, such as infections, trauma, neoplasms, inflammatory diseases, and systemic diseases with autonomic dysfunction. Few cases have been reported of bilateral tonic pupils associated with migraine attacks. CASE REPORT: Our aimed to describe the case of a young female patient with a history of chronic migraine without aura, who presented acutely with bilateral pupillary mydriasis during a migraine attack, characterized as tonic pupil, and to discuss the possible causes of mydriasis during a migraine attack.

INTRODUÇÃO: A pupila tônica ou pupila de Adie ocorre devido à denervação parassimpática e é caracterizada por midríase com pouca ou nenhuma resposta à luz, com contração pupilar à acomodação. É causada por patologias oculares, como infecções, traumas, neoplasias, doenças inflamatórias e doenças sistêmicas com disfunção autonômica. Poucos casos foram relatados de pupilas tônicas bilaterais associadas a crises de enxaqueca. RELATO DE CASO: Nosso objetivo foi descrever o caso de uma paciente jovem, com história de enxaqueca crônica sem aura, que apresentou agudamente midríase pupilar bilateral durante uma crise de enxaqueca, caracterizada como pupila tônica, e discutir as possíveis causas da midríase durante uma crise de enxaqueca. ataque de enxaqueca.

Guidelines for preventing and slowing myopia progression in Brazilian children / Diretrizes brasileiras para prevenir e retardar a progressão da miopia em crianças brasileiras

ABSTRACT This document on myopia control is derived from a compilation of medical literature and the collective clinical expertise of an expert committee comprising members from the Brazilian Society of Pediatric Ophthalmology and the Brazilian Society of Contact Lenses and Cornea. To manage myopia in children, the committee recommends corneal topography and biannual visits with cycloplegic refraction, along with annual optical biometry. For fast-progressing myopia, biannual biometry should be considered. Myopic progression is defined as an annual increase in spherical equivalent greater than 0.50 D/year or in axial length greater than 0.3 mm (until 10 years old) or 0.2 mm (above 11 years). The proposed treatments for myopia progression include environmental control, low concentration atropine, defocus glasses, contact lenses, or Ortho-K lenses, and combinations of these methods may be necessary for uncontrolled cases. Treatment should be sustained for at least 2 years. This document serves as a comprehensive guideline for diagnosing, treating, and monitoring pre-myopic and myopic children in Brazil.

RESUMO Esta revisão foi baseada na literatura médica e na experiência clínica de um comitê de especialistas membros da Sociedade Brasileira de Oftalmologia Pediátrica e da Sociedade Brasileira de Lentes de Contato e Córnea. Rotineiramente as crianças devem ser submetidas a topografia da córnea no primeiro exame e visitas semestrais com refração cicloplegiada e biometria óptica anual. A progressão da miopia foi definida como um aumento anual no equivalente esférico maior que 0,50 D/ano ou do comprimento axial maior que 0,3 mm (até 10 anos) ou 0,2 mm (mais de 11 anos). Os tratamentos propostos para a progressão são controle ambiental, atropina em baixa concentração, óculos com defocus, lentes de contato ou ortoceratologia, devendo-se considerar associações para casos não controlados. O tratamento deve ser realizado por pelo menos 2 anos. O presente documento é uma diretriz para diagnóstico, tratamento e acompanhamento de crianças pré-míopes e míopes no Brasil.

Dysregulated noradrenergic response is associated with symptom severity in individuals with schizophrenia.

Introduction: The locus coeruleus-noradrenaline (LC-NA) system is involved in a wide range of cognitive functions and may be altered in schizophrenia. A non-invasive method to indirectly measure LC activity is task-evoked pupillary response. Individuals with schizophrenia present reduced pupil dilation compared to healthy subjects, particularly when task demand increases. However, the extent to which alteration in LC activity contributes to schizophrenia symptomatology remains largely unexplored. We aimed to investigate the association between symptomatology, cognition, and noradrenergic response in individuals with schizophrenia. Methods: We assessed task-evoked pupil dilation during a pro- and antisaccade task in 23 individuals with schizophrenia and 28 healthy subjects. Results: Both groups showed similar preparatory pupil dilation during prosaccade trials, but individuals with schizophrenia showed significantly lower pupil dilation compared to healthy subjects in antisaccade trials. Importantly, reduced preparatory pupil dilation for antisaccade trials was associated with worse general symptomatology in individuals with schizophrenia. Discussion: Our findings suggest that changes in LC-NA activity - measured by task-evoked pupil dilation - when task demand increases is associated with schizophrenia symptoms. Interventions targeting the modulation of noradrenergic responses may be suitable candidates to reduce schizophrenia symptomatology.

The nonlinearity of pupil diameter fluctuations in an insight task as criteria for detecting children who solve the problem from those who do not.

Insights, characterized by sudden discoveries following unsuccessful problem-solving attempts, are fascinating phenomena. Dynamic systems perspectives argue that insight arises from self-organizing perceptual and motor processes. Entropy and fractal scaling are potential markers for emerging new and effective solutions. This study investigated whether specific features associated with self-organization in dynamical systems can distinguish between individuals who succeed and those who fail in solving insight tasks. To achieve this, we analyzed pupillary diameter fluctuations of children aged 6 to 12 during the 8-coin task, a well-established insight task. The participants were divided into two groups: successful (n = 24) and unsuccessful (n = 43) task completion. Entropy, determinism, recurrence ratio, and the ß scaling exponent were estimated using Recurrence Quantification and Power Spectrum Density analyses. The results indicated that the solver group exhibited more significant uncertainty and lower predictability in pupillary diameter fluctuations before finding the solution. Recurrence Quantification Analysis revealed changes that went unnoticed by mean and standard deviation measures. However, the ß scaling exponent did not differentiate between the two groups. These findings suggest that entropy and determinism in pupillary diameter fluctuations can identify early differences in problem-solving success. Further research is needed to determine the exclusive role of perceptual and motor activity in generating insights and investigate these results' generalizability to other tasks and populations.

Impact of acute psychosocial stress on attentional control in humans. A study of evoked potentials and pupillary response.

Psychosocial stress has increased considerably in our modern lifestyle, affecting global mental health. Deficits in attentional control are cardinal features of stress disorders and pathological anxiety. Studies suggest that changes in the locus coeruleus-norepinephrine system could underlie the effects of stress on top-down attentional control. However, the impact of psychosocial stress on attentional processes and its underlying neural mechanisms are poorly understood. This study aims to investigate the effect of psychosocial stress on attentional processing and brain signatures. Evoked potentials and pupillary activity related to the oddball auditory paradigm were recorded before and after applying the Montreal Imaging Stress Task (MIST). Electrocardiogram (ECG), salivary cortisol, and subjective anxiety/stress levels were measured at different experimental periods. The control group experienced the same physical and cognitive effort but without the psychosocial stress component. The results showed that stressed subjects exhibited decreased P3a and P3b amplitude, pupil phasic response, and correct responses. On the other hand, they displayed an increase in Mismatch Negativity (MMN). N1 amplitude after MIST only decreased in the control group. We found that differences in P3b amplitude between the first and second oddball were significantly correlated with pupillary dilation and salivary cortisol levels. Our results suggest that under social-evaluative threat, basal activity of the coeruleus-norepinephrine system increases, enhancing alertness and decreasing voluntary attentional resources for the cognitive task. These findings contribute to understanding the neurobiological basis of attentional changes in pathologies associated with chronic psychosocial stress.

Glasgow coma scale pupil score (GCS-P) and the hospital mortality in severe traumatic brain injury: analysis of 1,066 Brazilian patients / Escala de coma de Glasgow com resposta pupilar (ECC-P) e mortalidade hospitalar em traumatismo cranioencefálico grave: análise de 1.066 pacientes brasileiros

Abstract Background Pupil reactivity and the Glasgow Coma Scale (CCS) score are the most clinically relevant information to predict the survival of traumatic brain injury (TBI) patients. Objective We evaluated the accuracy of the CCS-Pupil score (CCS-P) as a prognostic index to predict hospital mortality in Brazilian patients with severe TBI and compare it with a model combining CCS and pupil response with additional clinical and radiological prognostic factors. Methods Data from 1,066 patients with severe TBI from 5 prospective studies were analyzed. We determined the association between hospital mortality and the combination of CCS, pupil reactivity, age, glucose levels, cranial computed tomography (CT), or the CCS-P score by multivariate binary logistic regression. Results Eighty-five percent (n = 908) of patients were men. The mean age was 35 years old, and the overall hospital mortality was 32.8%. The area under the receiver operating characteristic curve (AUROC) was 0.73 (0.70-0.77) for the model using the CCS-P score and 0.80 (0.77-0.83) for the model including clinical and radiological variables. The CCS-P score showed similar accuracy in predicting the mortality reported for the patients with severe TBI derived from the International Mission for Prognosis and Clinical Trials in TBI (IMPACT) and the Corticosteroid Randomization After Significant Head Injury (CRASH) studies. Conclusion Our results support the external validation of the CCS-P to predict hospital mortality following a severe TBI. The predictive value of the CCS-P for long-term mortality, functional, and neuropsychiatric outcomes in Brazilian patients with mild, moderate, and severe TBI deserves further investigation.

Resumo Antecedentes A reatividade pupilar e o escore da Escala de Coma de Glasgow (ECC) representam as informações clínicas mais relevantes para predizer a sobrevivência de pacientes com traumatismo cranioencefálico (TCE). Objetivo Avaliar a acurácia da ECC com resposta pupilar (ECC-P) como índice prognóstico para predizer mortalidade hospitalar em pacientes brasileiros acometidos por TCE grave e compará-lo com um modelo combinando ECC e resposta pupilar com fatores prognósticos radiológicos. Métodos Foram analisados dados de 1.066 pacientes com TCE grave de 5 estudos prospectivos. Foi determinada a associação entre mortalidade hospitalar e a combinação de ECC, reatividade pupilar, idade, níveis glicêmicos, tomografia computadorizada (TC) de crânio ou o escore ECC-P por regressão logística binária multivariada. Resultados Oitenta e cinco por cento (n = 908) dos pacientes eram homens. A média de idade foi de 35 anos e a mortalidade hospitalar geral foi de 32,8%. A AUROC (em português, Curva Característica de Operação do Receptor) foi de 0,73 (0,70-0,77) para o modelo utilizando o escore ECC-P e de 0,80 (0,77-0,83) para o modelo incluindo variáveis clínicas e radiológicas. O escore ECC-P mostrou acurácia semelhante na previsão da mortalidade relatada para pacientes com TCE grave derivados dos estudos International Mission for Prognosis and Clinical Trials in TBI (IMPACT, na sigla em inglês) e Corticosteroid Randomization After Significant Head Injury (CRASH, na sigla em inglês). Conclusão Nossos resultados apoiam a validação externa da ECC-P para prever a mortalidade hospitalar após um TCE grave. O valor preditivo da ECC-P para mortalidade a longo prazo, resultados funcionais e neuropsiquiátricos em pacientes brasileiros com TCE leve, moderado e grave precisam ser investigados.

Bilateral Acute Iris Transillumination Syndrome after Topical Moxifloxacin/Dexamethasone Initially Misdiagnosed as Uveitis: Case Report.

Bilateral acute iris transillumination (BAIT) syndrome is a rare condition of unknown etiology, characterized by acute onset of pigment dispersion in the anterior chamber, depigmentation of the iris, and heavy pigment deposition in the anterior chamber angle, with bilateral involvement in most cases. We present a case of a 46-year-old healthy woman, who developed BAIT in both eyes, following the use of topical moxifloxacin/dexamethasone for bilateral bacterial conjunctivitis, followed by a nonarteritic anterior ischemic optic neuropathy in the left eye.

Non-Miotic Improvement in Binocular Near Vision with a Topical Compound Formula for Presbyopia Correction.

INTRODUCTION: The aim of this case series was to examine the association between unaided binocular visual acuity for near vision and pupil change after the instillation of a special topical formulation for presbyopia treatment. METHODS: This was a case series consisting of consecutive participants with presbyopia aged 40-70 years who were tested for visual acuity and pupil diameter before and 2 h after instillation of a formulation of pilocarpine and phenylephrine drops (FOV Tears) for presbyopia. Participants underwent subjective refraction, photopic and scotopic pupil diameter measurement and unaided monocular and binocular visual acuity testing by logMAR for distance and near vision both pre- and post-instillation of eye drops. RESULTS: The study enrolled 363 subjects (n = 176 women, 48%) with a mean (± standard deviation) age of 50.4 ± 5.8 years. Mean spherical equivalent (SE) changed significantly (- 0.17 Diopters) after instillation of the FOV Tears formulation (p < 0.001). Post-instillation of eye drops, the scotopic pupil diameter decreased by 0.97 ± 0.98 mm, and the near visual acuity by logMAR improved significantly by nearly two lines (p < 0.01). In the linear regression analyses, age (p < 0.001) and SE pre-drop instillation (p < 0.001) were associated with unaided binocular visual acuity. The changes in photopic pupil diameter and the scotopic pupil diameter were not associated with unaided binocular visual acuity. CONCLUSIONS: The use of the pilocarpine and phenylephrine formulation (FOV Tears) improved binocular visual acuity for near vision in presbyopic patients, and the effect was independent of pupil change.

Reversible Bitemporal Hemihypokinetic Pupil Without Hemianopia: A New Chiasmal Sign.

Chiasmal syndromes present mostly with visual problems, such as changes in visual fields, decreased visual acuity, or dyschromatopsia (and classically without pupillary reflex defects). The prototypical bitemporal hemianopia upon visual field testing can easily suggest chiasmal compression due to sellar/suprasellar involvement. However, because of the complexity of the decussation of fibres at the optic chiasm and the presence of anatomical variants, unpredictable visual fields defects can be detected in chiasmal diseases. In some patients, especially in those who have undergone neurosurgical procedures, visual field examination and neuroimaging may not completely reflect the classical pattern of chiasmal visual loss. We describe a novel semiological sign, reporting a patient in which a pupillary bitemporal hemihypokinesia was not accompanied by hemianopia, with the phenomenon being abolished by surgical resection of the causative pituitary macroadenoma. In addition, this finding was an important tool in making the diagnosis.

Effect of pupil dilation on intraocular pressure in preterm and term infants / O efeito da dilatação da pupila na pressão intraocular em bebês pré-termo e a termo

ABSTRACT Purpose: To evaluate the effect of pupil dilation on intraocular pressure in preterm and term newborns. Methods: This prospective study involved 55 eyes of 28 preterm infants and 38 eyes of 20 term infants. The infants were divided into two groups according to their gestational ages at birth as follows: preterm group, <37 weeks and term group, ≥37 weeks. Pupil dilation was attained with tropicamide 0.5% and phenylephrine 2.5%. Intraocular pressure measurements were performed with Icare PRO (Icare Finland Oy, Helsinki, Finland) before and after pupil dilation. A paired t test was used to compare the measurements before and after pupil dilation. Results: The mean intraocular pressure change was -1.04 ± 3.03 mmHg (6.20/-11.40 mmHg) in the preterm group and -0.39 ± 2.81 mmHg (4.60/-9.70 mmHg) in the term group. A statistically significant difference in intraocular pressure was observed only in the preterm group after pupil dilation (p=0.01). Conclusion: An unexpected alteration in intraocular pressure in newborns may occur after pupil dilation, especially in preterm infants.

RESUMO Objetivo: Avaliar o efeito da dilatação da pupila sobre a pressão intraocular em recém-nascidos pré-termo e a termo. Métodos: Este estudo prospectivo envolveu 55 olhos de 28 bebês pré-termo e 38 olhos de 20 bebês a termo. Os bebês foram divididos em dois grupos, pré-termo e a termo, de acordo com a idade gestacional ao nascimento: grupo pré-termo <37 semanas; grupo a termo ≥37 semanas. A dilatação da pupila foi feita com tropicamida 0,5% e fenilefrina 2,5%. As medições da pressão intraocular foram realizadas com Icare PRO (Icare Finland Oy, Helsinki, Finlândia) antes e depois da dilatação da pupila. O teste t pareado foi usado para comparar as medidas antes e depois da dilatação da pupila. Resultados: A alteração média da pressão intraocular foi de -1,04 ± 3,03 mmHg (+6,20/-11,40 mmHg) no grupo pré-termo e -0,39 ± 2,81 mmHg (+4,60/-9,70 mmHg) no grupo a termo. Uma diferença estatisticamente significativa na pressão intraocular foi observada apenas no grupo pré-termo após a dilatação da pupila (p=0,01). Conclusão: Após a dilatação da pupila, pode ocorrer alteração inesperada da pressão intraocular em recém-nascidos, principalmente em bebês pré-termo.

Neural responses to sensory novelty with and without conscious access.

Detection of novel stimuli that violate statistical regularities in the sensory scene is of paramount importance for the survival of biological organisms. Event-related potentials, phasic increases in pupil size, and evoked changes in oscillatory power have been proposed as markers of sensory novelty detection. However, how conscious access to novelty modulates these different brain responses is not well understood. Here, we studied the neural responses to sensory novelty in the auditory modality with and without conscious access. We identified individual thresholds for conscious auditory discrimination and presented to our participants sequences of tones, where the last stimulus could be another standard, a subthreshold target or a suprathreshold target. Participants were instructed to report whether the last tone of each sequence was the same or different from those preceding it. Results indicate that attentional orientation to behaviorally relevant stimuli and overt decision-making mechanisms, indexed by the P3 event-related response and reaction times, best predict whether a novel stimulus will be consciously accessed. Theta power and pupil size do not predict conscious access to novelty, but instead reflect information maintenance and unexpected sensory uncertainty. These results highlight the interplay between bottom-up and top-down mechanisms and how the brain weights neural responses to novelty and uncertainty during perception and goal-directed behavior.

[Dioptric power of intraocular lens and dilatation in patients with cataract]. / Poder dióptrico del lente intraocular y dilatación en pacientes con catarata.

Background: Cataract surgery with intraocular lens implant is, nowadays, the most frequent surgical procedure in all the world. Its success depends on a lot of factors, one of the most important is the calculation of the exact dioptric power of intraocular lens. Objective: To compare the calculation of dioptric power of intraocular lens with and without dilatation in patients with cataract. Material and methods: Longitudinal study, the calculation of the dioptric power of the intraocular lens was determined in patients without and with pupillary dilation. The variables were age, gender, eye to study, keratometry, axial length, anterior chamber depth and dioptric power of the intraocular lens. Descriptive statistics and Student t test were performed. Results: There were 37 patients, 23 females and 14 males. The average age was 68 + 7.87 years. Sixty-four eyes were studied, 30 were right and 34 left. Statistically, there was only significant difference in K2 of the ocular biometry between patients without and with pupillary dilation when obtaining a value of p < 0.05. Conclusion: There are no changes in the calculation of the dioptric power of the Intraocular lens without and with pupillary dilation.

Introducción: la cirugía de catarata con implante de un lente intraocular es, hoy en día, el procedimiento quirúrgico más frecuente en todo el mundo. Su éxito depende de muchos factores, uno de los más importantes es el cálculo exacto del poder dióptrico del lente intraocular. Objetivo: comparar el cálculo del poder dióptrico del lente intraocular en los pacientes sin y con dilatación pupilar. Material y métodos: estudio longitudinal, en el que se determinó el cálculo del poder dióptrico del lente intraocular en pacientes con y sin dilatación pupilar. Las variables de estudio fueron: edad, género, ojo a estudiar, queratometría, longitud axial, profundidad de cámara anterior y poder dióptrico del lente intraocular. Se realizó estadística descriptiva y t de Student. Resultados: se estudiaron 37 pacientes, 23 mujeres y 14 hombres. La edad promedio fue de 68 ± 7.87 años. Se estudiaron 64 ojos, 30 fueron derechos y 34 izquierdos. Estadísticamente solo hubo diferencia significativa en K2 de la biometría ocular entre pacientes sin y con dilatación pupilar al obtenerse un valor de p ≤ 0.05. Conclusión: no existen cambios en el cálculo del poder dióptrico del LIO sin y con dilatación pupilar.

Ophthalmic effects of dexmedetomidine, methadone and dexmedetomidine-methadone in healthy cats and their reversal with atipamezole.

OBJECTIVES: The aims of this study were to evaluate and compare the effects that dexmedetomidine and methadone, either alone or in combination, have on the ocular variables of healthy adult cats when administered intramuscularly, as well as their reversal with atipamezole. METHODS: A randomized crossover blinded study of 10 healthy cats was used to assess the effect of 0.2 mg/kg methadone (MET), 7.5 µg/kg dexmedetomidine (D7), 10 µg/kg dexmedetomidine (D10), 7.5 µg/kg dexmedetomidine and 0.2 mg/kg methadone (DM7) and 10 µg/kg dexmedetomidine and 0.2 mg/kg methadone (DM10) on intraocular pressure (IOP), tear production and pupil diameter (PD). The animals were evaluated for 30 mins. Afterwards, atipamezole was administered and ocular variables were evaluated for 30 mins. RESULTS: D10, DM7 and DM10 significantly decreased mean IOP but MET or D7 did not. Tear production decreased significantly in all treatments, corresponding to 18%, 59%, 63%, 86% and 98% in MET, D7, D10, DM7 and DM10, respectively. PD increased in all treatments, but MET showed the highest PD. Thirty minutes after atipamezole (RT30), IOP returned to baseline with no difference between groups, and there was a significant increase in tear production, but the means were still different from baseline. CONCLUSIONS AND RELEVANCE: Dexmedetomidine decreases IOP and tear production but increases PD in healthy cats. Atipamezole can partly reverse those alterations. Low-dose dexmedetomidine (7.5 µg/kg) promotes sedation without changing the IOP. All protocols significantly decrease tear production, and Schirmer tear test after sedation is not representative of non-sedated values. Methadone induces quick onset mydriasis without changing the IOP.

Classifying the difficulty levels of working memory tasks by using pupillary response.

Knowing the difficulty of a given task is crucial for improving the learning outcomes. This paper studies the difficulty level classification of memorization tasks from pupillary response data. Developing a difficulty level classifier from pupil size features is challenging because of the inter-subject variability of pupil responses. Eye-tracking data used in this study was collected while students solved different memorization tasks divided as low-, medium-, and high-level. Statistical analysis shows that values of pupillometric features (as peak dilation, pupil diameter change, and suchlike) differ significantly for different difficulty levels. We used a wrapper method to select the pupillometric features that work the best for the most common classifiers; Support Vector Machine (SVM), Decision Tree (DT), Linear Discriminant Analysis (LDA), and Random Forest (RF). Despite the statistical difference, experiments showed that a random forest classifier trained with five features obtained the best F1-score (82%). This result is essential because it describes a method to evaluate the cognitive load of a subject performing a task using only pupil size features.

Poder dióptrico del lente intraocular y dilatación en pacientes con catarata / Dioptric power of intraocular lens and dilatation in patients with cataract

ntroducción: la cirugía de catarata con implante de un lente intraocular es, hoy en día, el procedimiento quirúrgico más frecuente en todo el mundo. Su éxito depende de muchos factores, uno de los más importantes es el cálculo exacto del poder dióptrico del lente intraocular. Objetivo: comparar el cálculo del poder dióptrico del lente intraocular en los pacientes sin y con dilatación pupilar. Material y métodos: estudio longitudinal, en el que se determinó el cálculo del poder dióptrico del lente intraocular en pacientes con y sin dilatación pupilar. Las variables de estudio fueron: edad, género, ojo a estudiar, queratometría, longitud axial, profundidad de cámara anterior y poder dióptrico del lente intraocular. Se realizó estadística descriptiva y t de Student. Resultados: se estudiaron 37 pacientes, 23 mujeres y 14 hombres. La edad promedio fue de 68 ± 7.87 años. Se estudiaron 64 ojos, 30 fueron derechos y 34 izquierdos. Estadísticamente solo hubo diferencia significativa en K2 de la biometría ocular entre pacientes sin y con dilatación pupilar al obtenerse un valor de p ≤ 0.05. Conclusión: no existen cambios en el cálculo del poder dióptrico del LIO sin y con dilatación pupilar.

Background: Cataract surgery with intraocular lens implant is, nowadays, the most frequent surgical procedure in all the world. Its success depends on a lot of factors, one of the most important is the calculation of the exact dioptric power of intraocular lens. Objective: To compare the calculation of dioptric power of intraocular lens with and without dilatation in patients with cataract. Material and methods: Longitudinal study, the calculation of the dioptric power of the intraocular lens was determined in patients without and with pupillary dilation. The variables were age, gender, eye to study, keratometry, axial length, anterior chamber depth and dioptric power of the intraocular lens. Descriptive statistics and Student t test were performed. Results: There were 37 patients, 23 females and 14 males. The average age was 68 + 7.87 years. Sixty-four eyes were studied, 30 were right and 34 left. Statistically, there was only significant difference in K2 of the ocular biometry between patients without and with pupillary dilation when obtaining a value of p < 0.05. Conclusion: There are no changes in the calculation of the dioptric power of the Intraocular lens without and with pupillary dilation