Corrección del efecto de desplazamiento angular horizontal de la cabeza en pruebas de estimulación visual en MATLAB / Correction of horizontal and angular head displacement effects by MATLAB visual stimulation tests / Correção do efeito do deslocamento angular horizontal da cabeça em testes de estimulação visual no MATLAB

RESUMEN Introducción: Las irregularidades en los movimientos oculares constituyen un indicador importante para diagnosticar determinadas enfermedades neurodegenerativas. La electrooculografía es la técnica más difundida para medir dichos movimientos oculares. Durante la realización de una prueba visual, el paciente puede realizar movimientos de cabeza indeseados que añaden perturbaciones a la señal electrooculográfica, modificando su morfología y, por tanto, alterando determinados parámetros diagnósticos. Objetivo: Desarrollar un método para corregir el efecto del desplazamiento angular horizontal de la cabeza en la señal electrooculográfica. Método: Se detalla un modelo matemático utilizado en la Universidad de Oriente desde marzo de 2021 a diciembre de 2021, para la implementación de la corrección en dos tipos de señales electrooculográficas artificiales con diferentes movimientos de cabeza horizontales. Resultados: Se evalúo cualitativamente el comportamiento del método utilizado a través de su implementación en señales generadas artificialmente en MATLAB. Finalmente se caracterizaron los efectos de la corrección en los parámetros diagnósticos de la señal electrooculográfica. Conclusiones: El método implementado demostró su validez para casos específicos, en el que se logra para dos tipos de señales eliminar los errores introducidos por el desplazamiento de la cabeza. La corrección mejora el error introducido en la amplitud de la señal electrooculográfica sin corregir y mantiene inalterables, a falta de un análisis más profundo, los demás parámetros diagnósticos.

ABSTRACT Introduction: Eye movement disorders are an important indicator for the diagnosis of certain neurodegenerative diseases. Electrooculography is the most widespread technique for measuring such eye movements. During the performance of the eye test, patients may forge unwanted head movements that add disturbances to the electrooculographic signal, modifying its morphological characteristic and, therefore, changing certain diagnostic parameters. Objective: To develop a method for the correction of the effect of the horizontal and angular head displacement by the electrooculographic signal. Method: It is detailed the use of a mathematical model for the correction of two types of artificial electrooculographic signals with different horizontal head movements at the Universidad de Oriente, from March 2021 to December 2021. Results: The behavior of the method used was evaluated qualitatively through its implementation in the signals generated artificially in MATLAB. Finally, the correction effects on the diagnostic parameters of the electrooculographic signal were characterized. Conclusions: The implemented method proved its validity for specific cases, in which it is possible to eliminate the errors caused by head displacement in two types of signals. The correction minimizes the error introduced in the uncorrected electrooculographic signal amplitude and keeps unchanged the other diagnostic parameters in absence of further analyses.

RESUMO Introdução: As irregularidades nos movimentos oculares são um importante indicador para diagnosticar certas doenças neurodegenerativas. A eletrooculografia é a técnica mais difundida para medir esses movimentos oculares. Durante um teste visual, o paciente pode realizar movimentos involuntários da cabeça que adicionam distúrbios ao sinal eletrooculográfico, modificando sua morfologia e, portanto, alterando alguns parâmetros diagnósticos. Objetivo: Desenvolver um método para corrigir o efeito do deslocamento angular horizontal da cabeça no sinal eletrooculográfico. Método: Um modelo matemático usado na Universidade de Oriente de março de 2021 a dezembro de 2021 é detalhado para a implementação da correção em dois tipos de sinais eletrooculográficos artificiais com diferentes movimentos horizontais da cabeça. Resultados: O comportamento do método utilizado foi avaliado qualitativamente através de sua implementação em sinais gerados artificialmente no MATLAB. Por fim, foram caracterizados os efeitos da correção sobre os parâmetros diagnósticos do sinal eletrooculográfico. Conclusões: O método implementado demonstrou sua validade para casos específicos, nos quais é possível eliminar os erros introduzidos pelo deslocamento da cabeça para dois tipos de sinais. A correção melhora o erro introduzido na amplitude do sinal eletrooculográfico não corrigido e mantém os demais parâmetros diagnósticos inalterados, na ausência de uma análise mais profunda.

Numerical study on adjusting parameters to improve gaze estimation using planar approximations from electro-oculogram signal voltage ratios

Gaze or eye movements are used as a communication interface in daily life. Herein, we developed a simple method for gaze estimations based on planar approximations of voltage ratios calculated from multiple electro-oculogram signals not affected by drift phenomena, which decrease accuracy. Subsequently, we conducted simulations using an eyeball battery model and investigated the effects of adjusting electrode arrangements, determination coefficients for planar approximations of voltage ratios, and threshold values for angles between simultaneous linear equations, to improve the estimation accuracy and decreased the number of required electrodes. Numerical experiments were used to identify arrangements of six electrodes with errors that were approximately 5° less than those of nine-electrode L-shaped arrangements, indicating improved estimation accuracy with fewer electrodes.

Result of Visual Evoked Potential, Electroretinography and Electrooculography in Normal Subjects Using MonPack 3 System

PURPOSE: We present the results of visual evoked potential (VEP), electroretinography (ERG), and electrooculography (EOG) in normal subjects using the Mon-pack 3 system (Metrovision). METHODS: VEP, ERG, and EOG were obtained in 92 normal eyes. The measurements followed the International Society for Clinical Electrophysiology of Vision (ISCEV) standardization protocol. In VEP, the standard electrode was placed on the forehead and the active electrode was attached on the occiput. In ERG, a 20-minute dark adaptation was performed after mydriasis, and an ERG-jet electrode was used. EOG was measured by attaching an electrode to each medial canthal skin. Each latent period and electric potential was measured with average, standard deviation, median, and 95% confidencenterval (95% CI). RESULTS: The mean P100 latency in pattern VEP was 104.36 ms, and P100 latency in flash VEP was 116.71 ms. For the maximal ERG response, the implicit times of a and b waves were 22.65 ms and 44.58 ms, respectively and the amplitude of a and b waves were 274.09 microv and 489.52 microv, respectively. For the ERG cone response, the implicit time of a and b waves were 18.21 ms and 33.40 ms, respectively, and the amplitude of a and b waves were 35.87 microv and 104.42 microv, respectively. The mean ERG oscillitatory potential was 285.53 microv. The average EOG Arden ratio was 2.54. CONCLUSIONS: VEP, ERG, and EOG results from normal subjects using the Mon-pack 3 system can be applied to the diagnosis of retina and optic nerve disease and basic research.

Alterações eletrofisiológicas na doença de Oguchi / Electrophysiological findings in Oguchi disease

Descrever as alterações eletrofuncionais em um caso raríssimo da Doença de Oguchi. Paciente do sexo feminino, italiana de 17 anos de idade se queixava de cegueira noturna. A resposta escotópica de bastonetes, do ERG era não registrável. A resposta escotópica ao estímulo branco forte demonstrava uma diminuição de amplitude da onda B. As respostas ao flicker de 30Hz e ao EOG eram dentro dos limites da normalidade. Era presente o fenômeno de Mizuo-Nakamura. Os exames eletrofuncionais são muito importantes no diagnóstico de certeza da doença de Oguchi. É nítida, no presente caso, a discordância entre EOG e ERG. Considerando a função dos bastonetes, as respostas normais do EOG contrastam com a ausência de respostas dos bastonetes em condições escotópicas no ERG. Mais estudos são necessários para entender o complexo mecanismo eletrofuncional dessa doença e melhor definir a origem dos componentes sensíveis à luz do EOG...

To describe the electrophysiological alterations in a very rare case of Oguchi's disease. A 17-year-old italian girl complaining of night blindness underwent complete ophthalmological exams, including electrophysiological tests. Rod responses were nondetectable in full-field electroretinogram (ERG). The photopic ERG funtions, including the 30 Hz flicker ERG response was normal, while the scotopic b-wave was diminished in amplitude. The electrooculography (EOG) ratios within the normal range were 208% in the right eye and 222% in the left eye. The Mizuo-Nakamura phenomenon was present. The electrophysiological tests are important tools in Oguchi's disease diagnosis. In the present case, it's clear the non correspondance between EOG and ERG. Considering the rod function, the normal EOG ratio contrast with non-detectable rod ERG responses. More studies are necessary to understand the compless electrofuntional mecanism of the disease helping to understand the origin of the light-sensitive component of the EOG...

Asociación entre la alteración de los movimientos oculares sacádicos y la esquizofrenia: un estudio de casos y controles / Altered Saccadic Eye Movements in Schizophrenia: A Case-Control Study

Contexto: Los pacientes con diagnóstico de esquizofrenia presentan alteraciones en los movimientos oculares, principalmente en los movimientos sacádicos; ésto se plantea como un marcador biológico de la enfermedad. Objetivo: Evaluar la alteración de los movimientos oculares sacádicos como marcadores biológicos en sujetos con diagnóstico de esquizofrenia. Metodología: Estudio de casos y controles en 50 pacientes con diagnóstico de esquizofrenia y 48 controles sanos emparejados por edad y sexo. Se diseñó un instrumento electrónico y un software para realizar la prueba electrooculográfi ca y analizar las señales mediante algoritmos computacionales. A cada participante se le realizó una entrevista psiquiátrica estructurada, un electrooculograma y una evaluación optométrica. Se caracterizó la señal electrooculográfi ca, identifi cando las regiones donde ocurrían las sacadas o saltos. De estas regiones se obtuvieron valores para los parámetros: amplitud, duración, ganancia, latencia y velocidad pico. Se hizo un análisis estadístico de variación con el método ANOVA de una vía o con el método no parámetrico de Kruskal-Wallis, cuando los datos no tenían distribución normal. Resultados: Se observaron diferencias estadísticamente signifi cativas entre ambos grupos únicamente para el parámetro “latencia” en amplitudes visuales mayores de 45 grados y en la realización del movimiento antisacádico para amplitudes visuales de 10 y 20 grados, patrones reportados por otros investigadores.

Context: Altered saccadic eye movements are considered biological markers of schizophrenia. Objective: To evaluate alterations of saccadic eye movements as biological markers in subjects diagnosed with schizophrenia. Methodology: Case-Control study in 50 patients diagnosed with schizophrenia and 48 healthy control subjects paired by age and gender. An electronic device and software were designed to perform the electro-oculographic test and to analyze the signals using computational algorithms. A structured psychiatric interview, an electro-oculogram and an optometric test were performed on all the participants. The electro-oculographic signal was then characterized, identifying the regions where the saccadic leaps occurred. Within these regions the parameters amplitude, duration, gain, latency and peak velocity were measured. A statistical analysis was performed using the one way ANOVA or the Kruskall-Wallis when the data did not have a normal distribution. Results: Statistically signifi cant differences were observed between both groups only for the “latency” in visual amplitudes larger than 45 degrees and in the anti-saccadic movement in visual amplitudes between 10 and 20 degrees, patterns that have been reported by other researchers.

Diagnosis and Management of Congenital Periodic Alternating Nystagmus

PURPOSE: To investigate clinical findings, diagnostic criteria and management for patients with congenital periodic alternating nystagmus (PAN). METHODS: A retrospective analysis of clinical findings and electrooculography (EOG) of patients with congenital PAN was performed. Thirteen patients diagnosed with congenital PAN from March 1992 to December 2002 were included. RESULTS: Of 13 patients, the median age at initial visit was 7 years old (range: 1 to 30 years). Eight patients had abnormal head posture. The mean value for the period of alteration was 265.7 seconds. Six patients who received either the modified Kestenbaum-Anderson procedure or four rectus muscle recession showed a significant decrease in amplitude and/or frequency of nystagmus, and showed statistically significant improvement in visual acuity in LogMAR after the procedures by 0.33+/-0.09 in right eye, 0.34+/-0.11 in the left eye, compared with preoperative acuities of 0.43+/-0.19 and 0.38+/-0.09 respectively. CONCLUSIONS: Congenital PAN requires the evaluation of nystagmus along with a thorough evaluation of eye movement and EOG. Close follow is necessary to evaluate the pattern of nystagmus. Also, either modified Kestenbaum-Anderson procedure or four rectus muscle recession could be effective, depending on the presence of abnormal head posture.

Clinical and Electro-Oculographic Characteristics of Ocular Flutter

BACKGROUND: Ocular flutter is a rare horizontal eye movement disorder characterized by rapid saccadic oscillations. Excessive discharge of burst neurons, and/or loss of tonic excitation of pause cells cause ocular flutter in several neurologic diseases. Ocular flutter can be easily differentiated from other saccadic oscillations with the aid of electro-oculography (EOG) findings showing an absence of intersaccadic intervals. METHODS: We analyzed EOG findings of ocular flutter in four patients. RESULTS: Ocular flutter, which was shown as rapid, repetitive, horizontal, symmetrical, and sinusoidal movements without intersaccadic intervals on EOG, was confirmed in four patients. The etiology of each patient was olivopontocerebellar atrophy (1 case), meningoencephalitis (2 cases), and lithium intoxication (1 case). CONCLUSIONS: Ocular flutter can be present in numerous neurologic diseases. Characteristic EOG findings are useful in the diagnosis of ocular flutter.

Electrooculographic Study of Latent Nystagmus

The authors analysed eleven patients with latent nystagmus who were diagnosed by clinical manifestation and electrooculography during six months. Among them, six patients had monocular amblyopia, four had binocular amblyopia and only one had normal visual acuity. All of them had manifest latent nystagmus which had a small amplitude of nystagmus in binocular fixation. Two of them showed typical latent nystagmus, jerky wave form characterized by decreasing velocity in slow phase and directing to fixing eye. Seven patients showed typical latent nystagmus wave form associated with pendular wave form and two patients showed jerky wave form with increasing velocity in slow phase. Therefore nine patients had componant of infantile nystagmus wave form. Ten of them had strabismus. Among them, five patients had hyper tropia. Three of the hypertropic patients showed dissociated vertical deviation. The authors suggest that the latent nystagmus is a kind of infantile nystagmus, and abnormal ocular conditions such as strabismus and amblyopia affects the infantile motor nystagmus.

Electrophysiologic Finding of Retinitis Pigmentosa Inversus and Differential Diagnosis from Peripapillary Choroidal Dystrophy

The authors found 3 cases of retinitis pigmentosa inversus who had characteristics that age of onset is between fifth and sixth decade, retinal lesion was seen around the optic disc and along the retinal vascular arcade, margin is discrete, and peripheral retina is morphologically normal. The authors performed routine ophthalmic examination, fluorescein angiography, electroretinography, electro-oculography. Fluorescein angiogram of retinitis pigmentosa inversus showed diffuse hyperfluoresce due to retinal pigment epithelium atrophy and partical hypofluoreseenee due to choriocapillary atrophy. Characteristic electroretinogram findings were moderate decrease of rod function and mild decrease of cone function. The authors also experienced 1 cases of peripapillary choroidal dystrophy and could differentiate it from retinitis pigmentosa inversus. Peripapillary choroidal dystrophy showed similar that of retinitis pigmentosa inversus in electroretinogram test, but showed diffuse and typical hypofluo rescence due to choriocapillary and retinal pigment epithelium atrophy according to the retinal lesion.

Simulated Nystagmus Blockage Syndrome

Manifest latent nystagmus (MLN) combined with esotropia may be confused with the nystagmus blockage syndrome (NBS), so the NBS may be overdiagnosed. The NBS is similar to MLN in the characteristics of the nystagmus and the clinical features, thus two diseases must be differentiated. In order to differentiate the MLN with esotropia from the NBS, accurate calibration of slow phase of nystagmus is essential with the aid of electro-oculography (EOG). With EOG recording, authors report a case of MLN associated with esotropia which may be misdiagnosed as the NBS.

A Case of Atypical Latent Nystagmus Associated with Infantile Nystagmus

The latent nystagmus seems to be absent when both eyes are open, but on covering one eye, bilateral jerky nystagmus is evoked with the fast phase toward the uncovered eye. The confirmed diagnosis of latent nystagmus can be made with the aid of the Electro-oculography (EOG). On EOG recording, we experienced a case of latent nystagmus in light, which showed the characteristics of infantile nystagmus in darkness.

THE ANALYSIS OF RELATED PARAMETERS OF SACCADE, SMOOTH PURSUIT AND OPTOKINETIC NYSTAGMUS IN HEALTHY SUBJECTS / 第二军医大学学报

The normal value of parameters of saccade, smooth pursuit and optokinetic nystagmus has been detected by recording the electro-oculograph in 29 healthy subjects.The results are as follows: 1.The reaction time of saccade is 259.04? 74.19,the mean velocity is 216.83?87.51/s in 15? target amplitude.No statistical significance has been found between sexes, but the reaction time is obviously longer in pre-puberty group.2.For smooth pursuit in 40% target velocity, gain is 0.976?0.08, phase lag is 3.95?7.69s,moothness is 0.925?1.49.No statistical significance has been found between sexes.3.In analysing the sequential process of saccade and smooth pursuit, it can't observed the tendency of decrement in latency.4.The gain of OKN in 14?/s velocity is between 0.689-0.808, the gain decreases following the increase of target velocity.The symmetry of OKN is 3.54?15.04% and there are 81.58% of OKN belonging macula type in healthy people.5.When the target velocity is in close each other,the velocity of fast phase of OKN is in close with the velocity of saccade.