ABSTRACT
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.
Subject(s)
Electrodes , Eye Movements , MethodsABSTRACT
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.
ABSTRACT
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.
Subject(s)
Age of Onset , Atrophy , Choroid , Diagnosis, Differential , Electroretinography , Fluorescein , Fluorescein Angiography , Retina , Retinal Pigment Epithelium , Retinaldehyde , Retinitis Pigmentosa , RetinitisABSTRACT
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.
Subject(s)
Calibration , Electrooculography , EsotropiaABSTRACT
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.