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Retraso en la maduración visual es el término utilizado para describir aquellos niños con incapacidad de fijar o seguir objetos en el ambiente, que no responden ante la proximidad de un objeto amenazante o un destello de luz, por ejemplo, abrir y cerrar los ojos; pero luego mejora a la edad de 6 meses sin tratamiento. Se incluyen dentro de las posibles causas la falta de oxígeno antes, durante o después del nacimiento, enfermedades producidas por virus o bacterias como la meningitis y el citomegalovirus, o una lesión traumática, aunque hoy en día queda poco consenso en cuanto a la etiología de este fenómeno. Estos niños con retraso en la maduración visual parecen ciegos, incapaces de centrar la atención, fijar o seguir cualquier parte del mundo visual. La exploración ocular y neurológica del niño es completamente normal. Los síntomas se resuelven sin tratamiento y con frecuencia, no se encuentra ninguna causa para la presentación inicial. El retraso en la maduración visual se clasifica en 3 grupos: el primero con retraso en la maduración visual como única anomalía y una recuperación rápida y completa. El segundo incluye aquellos casos con problemas oculares, como estrabismo, error refractivo elevado, retraso mental, entre otros, logrando una recuperación más lenta y a menudo incompleta. El tercer grupo incluye los casos con otras anomalías oculares

Delayed visual maturation is the term used to describe those children with inability to fix their eyes with the object or to visually follow them in the environment, who do not react to a threatening object or a gleam of light close to them, for example, by opening and closing their eyes. However, they generally improve their condition at the age of 6 months without any treatment. The possible causes of this disorder may be lack of oxygen, before, during or after birth, illnesses caused by viruses or bacteria, such as meningitis and cytomegalovirus, or a traumatic lesion, although there exists now minority consensus about the real etiology of this phenomenon. The children suffering delayed visual maturation seem to be blind, unable to focus attention, fix or visually follow any portion of the visual world. Ocular and neurological examination of the child is completely normal. Symptoms disappear without any treatment and the cause for the initial occurrence is usually unfound. The delayed visual maturation is classified into 3 groups, the first group with delayed visual maturation as the only anomaly and a quick and complete recovery. The second group includes those cases with ocular problems, namely strabismus, high refractive error, mental retardation, and others, in which recovery is slower and often incomplete. The third group includes cases with other ocular anomalies

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PURPOSE: To establish the relationship between upper eyelid saccades and upper eyelid pursuit movements. METHODS: Upper eyelid saccades and periodic sinusoidal upper eyelid pursuit movements were recorded in a sample of controls and patients with Graves upper eyelid retraction. A video-computerized system was used to register both types of movements that accompanied 60 degrees of eye rotation across the upper and lower hemifields. The forced harmonic oscillator model was used to fit saccadic and pursuit movements. RESULTS: Mean mid-pupil eyelid distance for the Graves patients (6.6 +/- 1.1 mm) was significantly higher than for the controls (4.6 +/- 0.8 mm; t = 7.18; P < 0.00001). Despite the difference in the upper eyelid resting position, saccades and pursuit eyelid movements of both groups were extremely well fitted by underdamped solutions and steady forced solutions of the harmonic oscillator model, respectively. For the controls, the amplitude of the pursuit movements was well correlated with the upward and downward saccades. The amplitude of the eyelid movements of the Graves patients (saccades and pursuit) was significantly reduced compared with that of the controls. CONCLUSIONS: Saccadic and pursuit movements of the upper eyelid can be described by the harmonic oscillator model. In healthy subjects and Graves patients, the amplitude of pursuit lid movements is correlated to the saccade amplitude. Pursuit eyelid movements are more difficult to register than saccades, and their measurements do not allow clear separation of the relaxation and contraction properties of the upper eyelid retractors.

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We present here a series of experiments exploring a special class of visual completion that is strictly tied to the perception of apparent motion. The stimuli consist of sparse random-dot arrays, in which dots remain in place. Changes of luminance or color of the dots at leading and trailing edges of an apparently moving region are integrated over space and time to produce the perception of well-defined contours, shapes, and color. We test how Vernier acuity of apparent motion-defined illusory bars depends on speed, density, and stimulus configurations. We found that higher speed of apparent motion reduces the Vernier acuity thresholds. These thresholds also decrease with increasing density of dots, whose luminance changes provide the apparent motion signal required for the perception of illusory contours. In subsequent experiments, we showed that luminance-defined flankers could seamlessly integrate with and improve the perception of apparent motion-defined contours, reducing their Vernier thresholds.

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INTRODUCTION: These two eye movements have not been previously studied in this condition by this method. METHODS: Five cases were studied. Both visual acuity and eye examination of anterior and posterior segments were normal. A Nicolet Nystar Plus system with chloride silver electrodes was used to record the EOG. RESULTS: Of the two systems under study, the smooth pursuit system showed the most relevant anomalies, both in the Duane's eye and in the apparently healthy eye. No correlation was found between the pursuit and optokinetic nystagmus disorders. In some cases, more significant abnormalities were observed in the clinically normal eye. CONCLUSIONS: The results clearly demonstrated a significant impairment of the pursuit system. This suggests that this motor disorder is not exclusively caused by hypoplasia or aplasia of the nucleus of the abducens nerve (VIth cranial nerve). These abnormalities might be related to a poor development of the rhombencephalon since both supramotor nuclei as well as the pathways of this system arise from this region of the embryonic brain. In the particular case of OKN, the supramotor nuclei have a different origin. Therefore, these systems might be affected differently.

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Objetivo: Avaliar os resultados clínicos da adaptação de lentes de contato Acuvue Toric®. Método: Quarenta pacientes amétropes astigmatas recrutados para o estudo foram submetidos à avaliação oftalmológica completa e testes com as lentes Acuvue Toric® parra a escolha dos parâmetros das lentes a serem prescritas. Ao final destes exames, 35 pacientes foram eleitos para participar do estudo. Os 35 pacientes retornaram para receber as lentes prescritas. Trinta pacientes retornaram, 15 dias depois, para o controle da adptação das lentes anteriores. Vinte e nove retornaram 30 dias depois para avaliação das lentes em uso. Em cada retorno mediu-se a AV monocular para longe, avaliou-se a centralização, movimento e posição da marca de orientação das lentes, assim como o desempenho visual, conforto, manuseio e satisfação geral. Para a graduação das respostas de desempenho adotou-se uma escala de notas que variava de 0 (péssimo) a 100 ( excelente). Resultados: Nas avaliações, o movimento das lentes foi considerado adequado em mais de 89 porcento dos olhos e a centralização em mais de 83 porcento dos olhos. Em metade dos olhos as lentes mantiveram a posição da marca de orientação em até 5° porcento e em mais de 75 porcento dos olhos dentro de 10°. Os valores de desempenho para acuidade visual foram superiores a 75, manuseio mais de 79, conforto mais de 89 e satisfação geral mais de 80. Conclusão: Neste estudo, as lentes Acuvue Toric® foram adaptadas em número expressivo dos indivíduos testados e tiveram desempenho bastante favorável em todas as categorias de avaliação.

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In order to assess the influence of visual stimulation in the triggering of imbalance and falls in the elderly population, the postural responses of 18 elderly patients with central vestibular disorders and clinical evidence of instability and falls were studied while receiving different types of visual stimuli. The stimulation conditions were: (i) no specific stimuli; (ii) smooth pursuit with pure sinusoids of 0.2 Hz as foveal stimulation; and (iii) optokinetic stimulation (OK) as retinal stimuli. Using a platform AMTI Accusway platform, the 95% confidence ellipse (CE) and sway velocity (SV) were evaluated with a scalogram using wavelets in order to assess the relationship between time and frequency in postural control. Velocity histograms were also constructed in order to observe the distribution of velocity values during the recording. A non-homogeneous postural behavior after visual stimulation was found among this population. In five of the patients the OK stimulation generated: (i) significantly higher average values of CE ( > 3.4+/-0.69 cm2); (ii) a significant increase in the average values of the SV ( > 3.89+/-1.15 cm/s) and a velocity histogram with a homogeneous distribution between 0 and 18 cm/s; and (iii) a scalogram with sway frequencies of up to 4 Hz distributed in both the X and Y directions (backwards and forwards and lateral) during visual stimulation with arbitrary units of energy density > 5. These three qualitative and quantitative aspects could be "markers" of visual dependence in the triggering of the mechanism of lack of equilibrium and hence falls in some elderly patients and should be considered in order to prevent falls and also to assist in the rehabilitation program of these patients.

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Patients with different vestibular disorders exhibit changes in postural behaviour when they receive visual stimuli, reproducing environmental stimulation. Postural control was studied using an AMTI Accusway platform, measuring the confidential ellipse (CE) and sway velocity (SV). Postural responses were recorded according to the following stimulation paradigm: i) without specific stimuli; ii) smooth pursuit with pure sinusoids of 0.2 Hz (foveal stimulation); and iii) optokinetic stimulation (retinal stimuli). Patients with central vestibular disorders (CVD), cerebellar damage and unilateral peripheral vestibular lesions (UPVL) in asymptomatic periods were studied. A group of normal subjects was studied as control. Signal processing was done with a scalogram by wavelets in order to observe the relation between time and frequency in postural control. While patients with CVD and cerebellar disease showed a significant increase in CE and SV in the three conditions of the paradigm compared to the normal group, the patients with UPVL showed no change. Wavelets processing showed that the main sway occurs in the Y axis (antero-posterior) and below at 0.4 Hz in normal subjects, while the CVD and cerebellar patients showed sway frequencies in both the X and Y axes. The clinical implications of these findings are discussed.

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A posiçäo do reflexo corneano provocado pela fixaçäo de um estímulo luminoso (teste de Hirscberg), posicionado a 1 metro de distância, foi estudado em 273 crianças com idades que variavam de 4 a 208 dias de vida. No primeiro mês de vida (n=139) os reflexos foram classificados como centralizados em 52,52 por cento das crianças, desviados nasalmente em 38,13 por cento e temporalmente em 9,35 p/cento das mesmas. A ocorrência dos desvios caiu abruptamente com a idade, segundo uma funçäo potência, aproximando-se de zero a partir do terceiro mês. A magnitude dos desvios dos reflexos foi quase inteiramente restrita à área pupilar. Num intervalo de tempo de 7 a 28 meses após essa primeira avaliaçäo, 63 crianças das 92 que apresentavam desvios dos reflexos, foram reexaminadas e apenas 2 apresentaram estrabismo. Concluiu-se que: 1) desvios precoces dos relfexos näo säo precursores de estrabismo, 2) grandes desvios dos reflexos näo podem ser considerados normais no primeiro trimestre de vida e 3) mais da metade das crianças examinadas no primeiro mês de vida apresentam reflexos centralizados

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Results of two recent studies suggest that a distinct subgroup of schizophrenic patients and their relatives have particularly deviant eye tracking. Such heterogeneity could be of considerable importance, as it may indicate significant pathophysiologic or etiologic heterogeneity in schizophrenia. An analysis of 101 consecutive-admission schizophrenic patients confirmed the existence of two distinct subgroups of patients with higher and lower levels of spatial [root mean square (RMS)] eye-tracking error. However, there was no heterogeneity in the disturbance of pursuit eye movements. Anticipatory saccades, which by definition add very large amounts of spatial tracking error, were more frequent in the "high" RMS error group. Rates of anticipatory saccades were similar in the "low" RMS error patient group and normal controls, and there was no heterogeneity in the expression of anticipatory saccades. Apparent heterogeneity in global indices of eye-tracking impairment in schizophrenia appears to be a measurement artifact reflecting the powerful influence of anticipatory saccades on global performance indices, rather than true heterogeneity in the expression of any specific eye movement abnormality.

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We studied horizontal visual tracking in 20 patients with unilateral cerebral lesions and in 10 age-matched control subjects. Five patients, all with posterior lesions, showed impaired smooth pursuit of predictable targets moving toward the side of the cerebral lesion. Using nonpredictable step-ramp stimuli, we identified two distinct deficits of visual tracking. The first was a unidirectional deficit of smooth pursuit, for targets moving toward the side of the lesion, in response to stimuli presented into either visual hemifield. The second deficit, identified in a sixth patient who did not show pursuit asymmetry to predictable targets, was a bidirectional inability to estimate the speed of a moving target in the visual hemifield contralateral to the side of the lesion; this caused inaccurate saccades to moving (but not stationary) targets and impaired smooth pursuit initiation. These visual tracking deficits were independent of homonymous hemianopia or hemispatial neglect. These two tracking deficits are similar to those described in rhesus monkeys with lesions of the medial superior temporal and middle temporal visual areas.

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