Saccades, pupil response and blink abnormalities in Huntington's disease patients during free viewing.

OBJECTIVE: Video-based eye tracking was used to investigate saccade, pupil, and blink abnormalities among patients with Huntington's disease (HD) who watched sequences of short videos. HD, an autosomal dominant neurodegenerative disorder resulting from a CAG mutation on chromosome 4, produces motor and cognitive impairments including slow or irregular eye movements, which have been studied using structured tasks. METHODS: To explore how HD affects eye movements under instruction free conditions, we assessed 22 HD patients and their age matched controls in a 10-minute video-based free viewing task. RESULTS: Patients with HD experienced a significant reduction in saccade exploration rate following video clip transitions, an increase in pupil reactions to luminance changes after clip transitions, and a significant higher blink rate throughout the task compared to the control group. CONCLUSIONS: These results show that HD has a significant impact on how patients visually explore and respond to their environment under unconstrained and ecologically natural conditions. SIGNIFICANCE: Eye tracking in HD patients revealed saccadic, pupil, and blink abnormalities in early HD patients, suggestive of brain circuitry abnormalities that probably involve brain stem deficits. Further research should explore the impact of these changes on the quality of life of the patients affected by the disease.

Conservative method for vertical electrooculogram attenuation based on local suppression of ongoing EEG artifact templates.

Eye movement during blinking can be a significant artifact in Event-Related Potentials (ERP) analysis. Blinks produce a positive potential in the vertical electrooculogram (VEOG), spreading towards the posterior direction. Two methods are frequently used to suppress VEOGs: linear regression to subtract the VEOG signal from the electroencephalogram (EEG) and Independent Component Analysis (ICA). However, some information is lost in both. The present algorithm (1) statistically identifies the position of VEOGs in the frontopolar channels; (2) performs EEG averaging for each channel, which results in 'blink templates'; (3) subtracts each template from the respective EEG at each VEOG position, only when the linear correlation index between the template and the segment is greater than a chosen threshold L. The signals from twenty subjects were acquired using a behavioral test and were treated using FilterBlink for subsequent ERP analysis. A model was designed to test the method for each subject using twenty copies of the EEG signal from the subject's mid-central channel (with nearly no VEOG) representing the EEG channels and their respective blink templates. At the same 200 equidistant time points (marks), a signal (2.5 sinusoidal cycles at 1050 ms emulating an ERP) was mixed with each model channel and the respective blink template of that channel, between 500 to 1200 ms after each mark. According to the model, VEOGs interfered with both ERPs and the ongoing EEG, mainly on the anterior medial leads, and no significant effect was observed on the mid-central channel (Cz). FilterBlink recovered approximately 90% (Fp1) to 98% (Fz) of the original ERP and EEG signals for L = 0.1. The method reduced the VEOG effect on the EEG after ERP and blink-artifact averaging in analyzing real signals. The method is straightforward and effective for VEOG attenuation without significant distortion in the EEG signal and embedded ERPs.

Blink Lagophthalmos in Graves Orbitopathy.

PURPOSE: To investigate the relationship between the kinematics of spontaneous blinks and the anterior area of the levator palpebrae superioris muscle in patients with Graves orbitopathy (GO). METHODS: This is a case-control study. The authors measured the margin reflex distance of the upper eyelid (margin reflex distance 1), the kinematics of spontaneous blinks, and the anterior area of levator palpebrae superioris muscle in CT coronal scans of patients with Graves upper eyelid retraction (GO) and a control group. The eye with the greatest margin reflex distance 1 was selected for analysis in each group. RESULTS: A total of 68 participants were included, with 36 in the GO group and 32 in the control group. In the GO group, the mean margin reflex distance 1 measured 6.5 mm, while in the control group, it was 3.9 mm. Almost all parameters related to the closing phase of spontaneous blinking activity, including amplitude, velocity, blinking rate, and interblink time, did not differ between the two groups. However, the effectiveness of the blink's amplitude (ratio of blink amplitude to margin reflex distance 1) and the main sequence (relationship between amplitude and velocity) were significantly reduced in the GO group compared with the control group. The area of the levator palpebrae superioris muscle was significantly larger in GO than in controls, with 71.4% of patients' muscles outside of the maximum range of the controls. CONCLUSIONS: In patients with GO, there is a reduction in blinking effectiveness, also known as blink lagophthalmos, which is a factor in the common occurrence of ocular surface symptoms. The increase in velocity with amplitude is also reduced in GO.

Spontaneous Blinking Kinematics After Frontalis Muscle Flap Advancement.

PURPOSE: To measure the spontaneous blinking metrics after blepharoptosis correction with frontalis muscle flap advancement. METHODS: A video system was employed to measure the amplitude and velocity of spontaneous blinking of 24 eyelids after the frontalis muscle flap surgery for blepharoptosis correction. A control group with no eyelid disorders was also measured. The data of 13 eyelids who had frontalis slings with autogenous fascia, which were previously collected with the same method in another study, were used for comparison. Digital images were used to measure the superior margin reflex distance and the presence of lagophthalmos during a gentle closure of the palpebral fissure. Superficial keratitis was assessed by corneal biomicroscopy. RESULTS: The mean amplitude of spontaneous blinking was 6.3 mm in controls, 2.6 mm in the frontalis flap patients, and 2.1 mm in the fascia sling group. The mean blink velocity was 133.8 mm/second in controls, 39.0 mm/second (3.7 standard error) after the frontalis flap, and 36.3 mm/second in patients with frontalis sling with fascia. For these 2 parameters, there was no statistical difference between the surgical groups, but a significant reduction when compared with the control group. No significant association was found between lagophthalmos and keratitis and the surgical procedure. CONCLUSIONS: There is no difference between the blinking metrics of eyelids operated using the frontalis muscle flap advancement technique or frontalis sling with autogenous fascia. The presence of lagophthalmos and keratitis also does not differ between the 2 procedures.

Blinking Parameters Do Not Normalize After Botulinum Toxin Therapy in Blepharospasm and Hemifacial Spasm Patients.

BACKGROUND: Little is known regarding changes induced by botulinum toxin injections on blinking parameters in blepharospasm (BSP) and hemifacial spasm (HFS) patients. The purpose of this study was to investigate objective changes induced by botulinum toxin (BoNT) injections on blinking parameters in BSP and HFS patients. METHODS: Thirty-seven patients with BSP and HFS were evaluated before and 30 days after receiving onabotulinumtoxinA injections. Twelve age-matched control subjects were also assessed. Pretreatment and post-treatment parameters were assessed and compared with normal controls. A high-speed camera and microlight-emitting diodes were used to register the blinking in patients and control groups. Outcomes were blinking frequency, amplitude, and maximum velocity of eyelid closure. RESULTS: BoNT injections led to a significant reduction in all parameters, compared with baseline, in BSP and on the affected side in HFS, respectively: 22% ( P < 0.001) and 20% ( P = 0.015) in amplitude; 21% ( P = 0.04) and 39% in frequency ( P = 0.002); and 41% ( P < 0.001) and 26% ( P = 0.005) in maximum closing velocity. Blinking amplitude ( P = 0.017 and P = 0.019) and velocity ( P < 0.001 for both groups) were significantly lower at 30 days on BSP and on the affected HFS side, when compared with controls. BSP and HFS patients presented a significantly lower velocity of eyelid closure, even before BoNT, compared with controls ( P = 0.004. and P < 0.001, respectively). CONCLUSIONS: Although blinking frequency became close to normal, amplitude and velocity after BoNT applications were significantly lower in BSP and on the affected side of HFS patients when compared with age-matched normal controls, demonstrating that blinking parameters do not normalize after treatment. The velocity of eyelid closure was shown to be significantly lower, even before BoNT treatment, when compared with control subjects.

A blinking focal pattern of re-entrant activity in the avian tectum.

Re-entrant connections are inherent to nervous system organization; however, a comprehensive understanding of their operation is still lacking. In birds, topographically organized re-entrant signals, carried by axons from the nucleus-isthmi-parvocellularis (Ipc), are distinctly recorded as bursting discharges across the optic tectum (TeO). Here, we used up to 48 microelectrodes regularly spaced on the superficial tectal layers of anesthetized pigeons to characterize the spatial-temporal pattern of this axonal re-entrant activity in response to different visual stimulation. We found that a brief luminous spot triggered repetitive waves of bursting discharges that, appearing from initial sources, propagated horizontally to areas representing up to 28° of visual space, widely exceeding the area activated by the retinal fibers. In response to visual motion, successive burst waves started along and around the stimulated tectal path, tracking the stimulus in discontinuous steps. When two stimuli were presented, the burst-wave sources alternated between the activated tectal loci, as if only one source could be active at any given time. Because these re-entrant signals boost the retinal input to higher visual areas, their peculiar dynamics mimic a blinking "spotlight," similar to the internal searching mechanism classically used to explain spatial attention. Tectal re-entry from Ipc is thus highly structured and intrinsically discontinuous, and higher tectofugal areas, which lack retinotopic organization, will thus receive incoming visual activity in a sequential and piecemeal fashion. We anticipate that analogous re-entrant patterns, perhaps hidden in less bi-dimensionally organized topographies, may organize the flow of neural activity in other parts of the brain as well.

Aspectos médico-legais do olho / Medicolegal aspects of the eye

RESUMO A oftalmologia fornece um campo vasto de conhecimentos necessários à medicina legal e às perícias médicas. O presente artigo objetivou revisar as informações na perícia criminal e cível, as repercussões da morte e os achados post-mortem que o exame ocular pode fornecer. Demonstrou-se que a perícia ocular é complexa e multifacetada, fornecendo ferramentas importantes para a classificação das lesões corporais, verificação da capacidade laboral, investigação da causa mortis e estimativa do tempo de morte.

ABSTRACT Ophthalmology provides a vast field of knowledge necessary for forensic medicine and medical expertise. The present article aimed to review the information on criminal and civil medical expertise, the repercussions of death, and the postmortem findings that the eye examination can provide. Ocular expertise has been shown to be complex and multifaceted, providing important tools to classify bodily injuries, verify work capacity, investigate the cause of death, and estimate the time of death.

Environmental noise at library learning commons affects student performance and electrophysiological functioning.

Environmental noise (EN) refers to unpleasant harmful sounds that deteriorates living conditions. Therefore, this study aims to investigate how EN affects students at learning commons, where EN increases between 70 and 90 dBA, and which levels disturb psycho-physiologically. For this purpose, 16 students of Tecnologico de Monterrey were recruited: nine men and seven women. They were divided into four groups, and were involved in two activities: to solve a puzzle of 300 pieces without and with EN at 75 dBA. In both activities, a summative evaluation based on the level of puzzle completeness, and the electrophysiological monitoring of heart and blink rate, and neural electrical activity were conducted. Results showed that student performance was 4% higher in a quiet room than in learning commons. EN increased heart rate in 3.48%, and blink rate in 22.91%, and neural electrical activity was reduced at least in 3%, regardless of task demands. The findings of the present study suggest that academic work is difficult to undertake in learning commons when EN is above the permissible limit, and what diminishes the performance of students and alters their electrophysiological functioning.

Basilar artery dolichoectasia an unusual and rare cause of secondary trigeminal neuralgia: a clinical report / Dolicoectasia da artéria basilar uma causa incomum e rara de neuralgia do trigêmeo secundária: um relato clínico

Objective: Patients with Trigeminal Neuralgia often consults a dentist for relief of their symptoms as the pain seems to be arising from teeth and allied oral structures. Basilar artery Dolichoectasia is an unusual and very rare cause of secondary Trigeminal Neuralgia as it compresses the Trigeminal nerve Root Entry Zone. Case reports: We report three cases of Trigeminal Neuralgia caused by Basilar artery Dolichoectasia compression. The corneal reflex was found absent in all three of the cases along with mild neurological deficits in one case. Multiplanar T1/T2W images through the brain disclosed an aberrant, cirsoid (S-shaped) and torturous Dolichoectasia of basilar artery offending the Trigeminal nerve Root Entry Zone. Discussion:Based on these findings we propose a protocol for general dentist for diagnosis of patients with trigeminal neuralgia and timely exclusion of secondary intracranial causes. Conclusion: General dentists and oral surgeons ought to consider this diagnosis in patients presenting with chronic facial pain especially pain mimicking neuralgia with loss of corneal reflex or other neurosensory deficit on the face along with nighttime pain episodes. Timely and accurate diagnosis and prompt referral to a concerned specialist can have an enormous impact on patient survival rate in such cases (AU)

Objetivo: Pacientes com Neuralgia do Trigêmeo frequentemente consultam um dentista para alívio de seus sintomas visto que a dor parece surgir dos dentes e estruturas orais relacionadas. A Dolicoectasia da artéria basilar é uma causa incomum e muito rara de Neuralgia do Trigêmeo secundária, pois comprime a zona de entrada da raiz do nervo trigêmeo. Relatos de casos: Relatamos três casos de Neuralgia do Trigêmeo causada por compressão por Dolicoectasia da artéria basilar. O reflexo da córnea se encontrava ausente em todos os três casos, juntamente com leves déficits neurológicos em um caso. Imagens multiplanares T1/T2W através do cérebro revelaram uma Dolicoectasia cirsóide (em forma de S) anômala e tortuosa da artéria basilar que atingiu a zona de entrada da raiz do nervo trigêmeo. Discussão: Com base nesses achados, propomos para o dentista clínico-geral um protocolo para diagnóstico de pacientes com Neuralgia do Trigêmeo e exclusão oportuna de causas intracranianas secundárias. Conclusão: Os dentistas clínicos-gerais e cirurgiões orais devem considerar este diagnóstico em pacientes que apresentam dor facial crônica, especialmente dor que mimetiza neuralgia com perda do reflexo da córnea ou outro déficit neurossensorial na face junto com episódios de dor noturna. O diagnóstico oportuno e preciso e o encaminhamento imediato a um especialista em questão podem ter um enorme impacto na taxa de sobrevida do paciente em tais casos (AU)

Motor Dysfunction as a Prodrome of Parkinson's Disease.

BACKGROUND: Recognition of motor signs in the prodromal stage could help identify those at risk of developing Parkinson's disease (PD). OBJECTIVE: This study identified motor symptoms and signs in individuals suspected of having PD but who did not have a progressive reduction in the speed and amplitude of finger tapping or other physical signs indicative of bradykinesia. METHODS: 146 patients, who had symptoms or signs suggestive of PD, were serially evaluated by a movement disorder specialist, using the Movement Disorder Society Unified Parkinson's Disease Rating Scale (MDS-UPDRS) Part III and video recordings. If the patients 'converted' to PD during follow-up, they were categorized as cases and compared with those who did not meet PD criteria during follow-up (non-cases). RESULTS: The 82 cases were more likely to have action dystonia or postural/action/rest tremor of a limb (OR 2.8; 95% CI 1.1-7.1; p = 0.02), a reduced blink rate at rest (OR 2.3; 95% CI 1.2-4.6; p = 0.01), anxiety (OR 8.9; 95% CI 2.6-31.1; p < 0.001), depression (OR 7.0; 95% CI 2.9-17.2; p < 0.001), or a frozen shoulder (OR 3.1; 95% CI 1.6-6.2) than the 64 'non-cases'.A reduction of the fast blink rate was common in patients who met the criteria for PD (p < 0.001). CONCLUSIONS: This study emphasizes that motor dysfunction is a component of the clinical prodrome seen in some patients with PD.

Analysis of blink activity and anomalous eyelid movements in patients with hemifacial spasm.

To assess spontaneous blinking and anomalous eyelid movements in patients with hemifacial spasm with an emphasis on interocular differences. Spontaneous eyelid movements were registered bilaterally for 3 min using a high-speed video camera in 28 patients with hemifacial spasm (HFS) who had not been treated with botulinum toxin injections for at least 5 months. The degree of blink conjugacy, maximum velocity, and amplitude of the closing phase of the blinks were determined for the affected and non-affected sides. Out of the 28 subjects, 23 (82%) presented with abnormal nonconjugate spasms that were similar to blinks, and in 17 (61%), high-frequency eyelid twitches were detected between blinks on the affected eye. The rate of nonconjugate blink-like spasms ranged from 0.3 to 24.7 movements/min. With regard for conjugate blinks, there was no significant interocular difference in amplitudes or eyelid closure velocities. The amplitude and velocity were significantly lower for nonconjugate movements than for spontaneous blinks. HFS is a unique condition in which complex patterns of eyelid movements, including both conjugate and nonconjugate movements, are present. Conjugate movements correspond to spontaneous blinking, and the same metrics were observed in affected and non-affected eyes. Nonconjugate movements correspond to anomalous nonconjugate blink-like spasms and high-frequency eyelid twitches in the affected eye, both of which were characterized by lower amplitudes and velocities than were observed in conjugate movements.

The Three Nociceptive Responses of the Orbicularis Oculi Reflex in Alzheimer's Disease: State of the Evidence and Meta-analysis.

There is an emerging belief that electrically elicited blink reflexes (BR) may distinguish Alzheimer's disease (AD) from other disorders characterized by memory dysfunction. To qualitatively and quantitatively distinguish the effects that electrical stimulation has over the blink reflex (eBR) recorded from patients with AD and healthy controls (HCs), we did a systematic review of the literature, and conducted a meta-analysis. Following our selected criteria, 94 AD patients and 97 HCs were identified from articles published in English between 1950 and 2017. Although the 3 responses (R1, R2 and R3) of the eBR were studied in a number of patients, only the R2 response was quantified in all studies. Thresholds and stimulation intensities parameters were found to be used in a miscellaneous form, and the majority of times, such parameters deviated from validated guidelines. The stimulation frequencies used to elicit the BR responses ranged between 0.14 and 0.2 Hz. These frequencies favored HCs compared with AD patients (odds ratio = 1.08; 95% CI = 0.30-1.85), I2 = 0% [P = .99]; Q = 271.89 [df = 7, P < .000]). Egger's regression test suggested publication bias (intercept = 32.38; 95% CI = -8.98 to -3.2; P = .001). Our results unveiled key shortcomings in the data reported; such shortcomings need to be corrected in future AD research looking for obtaining more reliable and reproducible eBR studies; otherwise, interventions may be misleading.

New findings in facial-onset sensory and motor neuronopathy (FOSMN) syndrome.

Facial-onset sensory and motor neuronopathy (FOSMN) syndrome represents a rare, slowly progressive, lower motor neuron disease with sensory compromise, involving mainly the face, bulbar region and upper limbs. However, non-motor symptoms and neurogenetic studies have rarely been evaluated in large case series. In the present study, 10 unrelated Brazilian patients with FOSMN syndrome underwent extensive clinical, laboratory, neurophysiological and neurogenetic assessment. Median age at symptom onset was 52.1 years, and men and women were equally affected. Patients presented with hemifacial or bilateral facial paresthesia and weakness, which evolved with dysphagia, dysphonia, and facial and tongue atrophy and, finally, a dropped-head, upper limb weakness and syringomyelia-like sensory disturbances in the upper limbs. All 10 patients showed chronic diffuse neurogenic compromise of bulbar, cervical and thoracic myotomes, and abnormal blink reflex tests. A positive family history of neurodegeneration was identified in six cases, and revealed pathogenic gene variants in three families (involving VCP, TARDBP and CHCHD10). Thus, our case series has revealed new findings regarding FOSMN syndrome: (i) its clinical course is not always benign, with poorer prognoses associated with dropped-head syndrome and early bulbar compromise; (ii) FOSMN syndrome may be part of a complex familial neurodegenerative spectrum; and (iii) a definite genetic basis may be observed in some cases.

Long-Term Effects of Frontalis Fascial Slings on the Elastic Properties of the Upper Eyelid.

PURPOSE: To measure the long-term effects of frontalis slings with fascial tissues on the downward eyelid saccadic movements Methods: Downward lid saccades for 10, 20, 30, 40, and 50 degrees of downgaze were measured in a sample of 19 patients with congenital ptosis who underwent frontalis slings with fascia lata (autogenous and banked) and temporalis fascia. Mean postoperative time was 10.7 years ± 3.8 SD. Seventeen age-matched normal subjects comprised the control group. Lid movements as well as the magnitude of brow motion were quantified in all participants with an opto-electronic device that automatically corrected any head movement. RESULTS: Most patients (77.4%) displayed lagophthalmos on eyelid closure. The lid saccades of the patients were severely restricted and did not increase beyond 30 degrees of downgaze. The maximum velocity of lid saccades was also abnormally low. Although the pre- and postoperative lid positions did not differ between eyes operated with the three types of slings, interocular analysis of patients who had bilateral surgery showed that the restrictive effect on the saccadic movements was more asymmetrical with banked fascia than with autogenous tissue. Overall, there was a significant negative correlation between the surgical effect with frontalis contraction and maximum saccadic amplitude. While in controls brow motion accounted for about 3.3-9.3% of the lid saccades, it was responsible for more than 43.5-57.4% lid movements in the patients. CONCLUSION: Fascial slings have a permanent restrictive effect on the elastic properties of the lids. Postoperative lagophthalmos is a natural consequence of any type of fascial sling. Downward saccadic amplitude is negatively correlated with the surgical effect with frontalis contraction.

Blink rate is associated with drug-induced parkinsonism in patients with severe mental illness, but does not meet requirements to serve as a clinical test: the Curacao extrapyramidal syndromes study XIII.

BACKGROUND: Drug-induced parkinsonism (DIP) has a high prevalence and is associated with poorer quality of life. To find a practical clinical tool to assess DIP in patients with severe mental illness (SMI), the association between blink rate and drug-induced parkinsonism (DIP) was assessed. METHODS: In a cohort of 204 SMI patients receiving care from the only mental health service of the previous Dutch Antilles, blink rate per minute during conversation was assessed by an additional trained movement disorder specialist. DIP was rated on the Unified Parkinson's Disease Rating Scale (UPDRS) in 878 assessments over a period of 18 years. Diagnostic values of blink rate were calculated. RESULTS: DIP prevalence was 36%, average blink rate was 14 (standard deviation (SD) 11) for patients with DIP, and 19 (SD 14) for patients without. There was a significant association between blink rate and DIP (p < 0.001). With a blink rate cut-off of 20 blinks per minute, sensitivity was 77% and specificity was 38%. A 10% percentile cut-off model resulted in an area under the ROC curve of 0.61. A logistic prediction model between dichotomous DIP and continuous blink rate per minute an area under the ROC curve of 0.70. CONCLUSIONS: There is a significant association between blink rate and DIP as diagnosed on the UPDRS. However, blink rate sensitivity and specificity with regard to DIP are too low to replace clinical rating scales in routine psychiatric practice. TRIAL REGISTRATION: The study was started over 20 years ago in 1992, at the time registering a trial was not common practice, therefore the study was never registered.

Bereitschaftspotential preceding eyelid blinks in Parkinson's disease.

METHODS: Ten PD patients in stages 1 and 2 of the Hoehn & Yahr classification were compared to 18 healthy controls. Artifact-free EEG segments of two seconds preceding the onset of the blink potential were averaged and analyzed, and the statistical significance of the measured amplitudes were evaluated by analysis of variance models. RESULTS: The presence of a BP in the PD patients was demonstrated. The mean amplitudes at 0 ms were respectively 0.6 µV and 3.3 µV for the BP patients and the normal controls, respectively. CONCLUSIONS: The BP amplitudes were significantly smaller in PD patients than normal participants. The amplitudes of the BP were not modified by levodopa.

Bereitschaftspotential preceding eyelid blinks in Parkinson's disease / Potencial de Bereitschafts precedendo o piscamento ocular na doença de Parkinson

ABSTRACT The Bereitschaftspotential (BP) is a negative wave observed in EEG retrograde averaging, preceding a motor act. The objective was to study the BP preceding voluntary eyelid blinks in Parkinson's disease (PD) patients during off and on phases of levodopa. Methods Ten PD patients in stages 1 and 2 of the Hoehn & Yahr classification were compared to 18 healthy controls. Artifact-free EEG segments of two seconds preceding the onset of the blink potential were averaged and analyzed, and the statistical significance of the measured amplitudes were evaluated by analysis of variance models. Results The presence of a BP in the PD patients was demonstrated. The mean amplitudes at 0 ms were respectively 0.6 µV and 3.3 µV for the BP patients and the normal controls, respectively. Conclusions The BP amplitudes were significantly smaller in PD patients than normal participants. The amplitudes of the BP were not modified by levodopa.

RESUMO O Potencial de Bereitschafts (PB) é uma onda negativa observada retrogradamente no EEG precedendo um ato motor. Objetivo Estudar o PB precedendo o piscamento palpebral voluntário em pacientes com doença de Parkinson (DP) durante as fases off e on da levodopa. Foram comparados dez pacientes com DP nos estágios 1 e 2 de Hoehn & Yahr com 18 controles saudáveis. Os segmentos de EEG livres de artefatos 2 segundos antes do início do potencial foram calculados e analisados e a significância estatística das amplitudes foi medida por modelos de análise de variância. Resultados A presença de PB nos pacientes com DP foi demonstrada. As amplitudes médias a 0 ms foram respectivamente 0,6 μV e 3,3 μV para os pacientes com DP e controles respectivamente. Conclusões As amplitudes do PB foram significativamente menores nos pacientes com DP do que controles. As amplitudes do PB não foram modificadas pela levodopa.

Estudio de la frecuencia de parpadeo y evaluación de la película lagrimal en superficie ocular de cobayos / Eye blinking frequency studies and tear film evaluation in guinea pig's ocular surface

OBJETVOS: La Queratopatía Climática Esferoidea (QCE) es una enfermedad degenerativa de la córnea humana caracterizada por la agregación de proteínas bajo el epitelio y una progresiva opacidad corneal, causada por condiciones ambientales desfavorables. Si bien esta patología fue descripta por primera vez hace más de cien años, en la actualidad no existe un modelo experimental de QCE que permita avanzar en el conocimiento de la etiopatogenia de la misma para plantear posibles tratamientos. En el intento por desarrollar este modelo en cobayos y debido a la escasa bibliografía disponible que describa la anatomía, fisiología y superficie ocular de estos animales, realizamos diferentes tests fisiológicos de superficie ocular en cobayos y lo compararemos con el humano. MÉTODOS: Para estos estudios se utilizaron 15 cobayos. Se realizaron videograbaciones de los mismos en un ambiente de tranquilidad y bajo ciertos estímulos para estudiar la dinámica de parpadeo y sueño. Con el fin de analizar la producción y la estabilidad del film lagrimal, se realizaron test de Schirmer, medición de la altura del menisco lagrimal inferior por OCT visante y tiempo de ruptura precorneal (TRP) respectivamente. RESULTADOS: El cobayo parpadea de forma completa y parcial, siendo más frecuente ésta última modalidad. La frecuencia y tipo de parpadeos/ minuto fue: Total= 2.35± 0.87; completos= 0.68±0.43; parciales=1.49±0.75. Su frecuencia de parpadeo es 5 veces menor que en humanos. La respuesta palpebral frente a diferentes estímulos externos fue escasa. Los cobayos no poseen hábitos nocturnos como muchos roedores y duermen por cortos períodos. A menudo no cierran completamente los ojos. Test de Schirmer cobayos: 8.14±1.86 mm/5 min (Humanos: 11.9 ± 6.79 mm/5 min). Altura menisco inferior cobayos: 0,206 ± 0,059 mm (Humanos: 0,277 ± 0,033 mm). TRP cobayos: 2-3 min. (Humanos: 10-15 seg). CONCLUSIONES: Los resultados obtenidos muestran que el cobayo, a diferencia de humanos, tiene una frecuencia de parpadeo menor. A su vez, esto se puede correlacionar con una producción de lágrima disminuida (objetivada con Test de Schirmer) y una mayor estabilidad de la película lagrimal, como lo evidencia el prolongado TRP. (AU)

PURPOSE: Climatic spheroidal keratophaty (CSK), also known as climatic droplet keratopathy (CDK), is a degenerative human corneal disease characterized by protein aggregation under the corneal epithelium that leads to a progressive corneal opacity. Of unknown etiology, it is related to harsh environmental conditions. Although CSK was described many years ago and no experimental model of the disease is still available, we perform different physiological test on the guinea pig´s ocular surface and compare the results with human parameters. METHODS: 15 guinea pigs were used for this study. Video recordings of their behavior in a quiet environment and under certain stimulus were performed to study the blinking and sleeping dynamic. Test de Schirmer, Inferior tear meniscus height measurement, Break up time (BUT) test were performed, with the aim of analyze the tear film production and stability. RESULTS: The guinea pig blinks in both a complete and a partial way, being more frequent the last one. The blink type and frequency were: Total = 2.35± 0.87; complete= 0.68±0.43; partial=1.49±0.75. The blink frequency is 5 times smaller than in humans. The eyelid response against different external stimuli was poor. The night habits of this animals were different compared with other rodents, they sleep for a short periods of time. They often do not close their eyes completely. Schirmer test in guinea pigs was 8.14±1.86 mm/5 min (humans: 11.9 ± 6.79 mm/5 min). Inferior tear meniscus height measurement in guinea pigs was 0,206 ± 0,059 mm (humans: 0,277 ± 0,033 mm). BUT in Guinea Pig: 2-3 min. (Humans: 10-15 seg). CONCLUSIONS: Guinea Pigs have a short blink frequency unlike humans, a decreased tear production, and an increased tear film stability. (AU)