Lucha epidemiológica contra pandemia COVID-19: Impacto de las medidas sociales en el SVI / Epidemiological fight against the COVID-19 pandemic: Impact of social measures on IVS

La lucha epidemiológica contra la pandemia COVID-19 ha incluido medidas sociales como el confinamiento y el cierre de actividades laborales y académicas. A consecuencia, tareas que se llevaban a cabo en el contexto presencial debieron ser ejecutadas desde los hogares, adoptando estrategias como el teletrabajo y la educación virtual, haciendo necesario el uso de herramientas como ordenadores y laptops. De allí que las personas han incrementado la exposición a las pantallas de dispositivos electrónicos, como son computadoras y laptops, trayendo como consecuencia afectaciones en la salud visual de las personas tales como el síndrome visual informático (SVI). Se realizó un estudio transversal con el objetivo de determinar la afectación por SVI en la población peruana y su relación con la exposición prolongada a DEV, generada a raíz de las medidas sociales de enfrentamiento a la pandemia de COVID-19. El tiempo promedio en que los sujetos de nuestro estudio usaron DEV dentro de los hogares se acrecentó un 120%, es decir 4,26±2,36 horas diarias adicionales al comparar con el año anterior a la pandemia COVID-19. La adopción masiva de actividades como el teletrabajo y la educación virtual podrían explicar el hecho que los grupos de empleados/patronos y estudiantes fueron los mayores usuarios de DEV, con 10,41 y 9,32 horas diarias. De acuerdo a los hallazgos obtenidos, es estadísticamente válido afirmar que las medidas sociales para enfrentar la pandemia COVID-19 indujeron al aumento en la prevalencia de SVI en los pobladores peruanos (p<0,001). En la actual investigación, la proporción de individuos que manifestaron SVI pasó de 38 a 64%, antes y durante la aplicación de las medidas, respectivamente(AU)

The epidemiological fight against the COVID-19 pandemic has included social measures such as confinement and the closure of work and academic activities. As a consequence, tasks that were carried out in the face-to-face context had to be carried out from homes, adopting strategies such as teleworking and virtual education, requiring the use of tools such as computers and laptops. Hence, people have increased exposure to the screens of electronic devices, such as computers and laptops, resulting in effects on people's visual health such as computer vision syndrome (SVI). A cross-sectional study was carried out in order to determine the affectation by SVI in the Peruvian population and its relationship with prolonged exposure to DEV, generated as a result of social measures to cope with the COVID-19 pandemic. The average time in which the subjects in our study used DEV within homes increased by 120%, that is, 4.26 ± 2.36 additional daily hours when compared to the year before the COVID-19 pandemic. The massive adoption of activities such as teleworking and virtual education could explain the fact that groups of employees / employers and students were the largest users of DEV, with 10.41 and 9.32 hours per day. According to the findings obtained, it is statistically valid to affirm that the social measures to face the COVID-19 pandemic induced an increase in the prevalence of SVI in the Peruvian population (p <0.001). In the current investigation, the proportion of individuals who manifested SVI went from 38 to 64%, before and during the application of the measures, respectively(AU)

Effect of disparity on the perception of motion-defined contours

We present three experiments that explored the effect of binocular disparity on the perception of contours defined by motion in a Spatiotemporal Boundary Formation. Depending on the disparity, the stimulus is perceived as an object that moves behind a holed surface (occluded configuration) or as a luminous transparency that moves over a surface that contains dots (occluding configuration). In all of the experiments, we used a Vernier task to assess the strength of contour perception. In the first experiment, we measured acuity as a function of disparity for a range of speeds and dot densities. The results showed that, despite the difference in the percepts, acuity was similar in both situations, replicating the dependence on speed and dot density demonstrated in previous studies. In the second experiment, the results showed that the dynamics of contour integration were identical for both occluded and occluding configurations. In the third experiment, we tested whether the mechanism of contour integration works independently from the interpretation of the scene. In this experiment, we inverted the disparity during stimulus presentation so that the stimulus switched between occluded and occluding configurations. The results showed that the switch of the depth order increased the threshold to the value obtained with a shorter presentation time. This might be produced by a resetting of the integration process driven by the change of depth order. The results are discussed within a conceptual model that places the process of contour integration in the context of the perception of objects in a Spatiotemporal Boundary Formation...

Real Stereopsis Test Using a Three-Dimensional Display with Tridef Software

PURPOSE: To investigate horizontal image disparity in three-dimensional (3-D) perception using 3-D animations in normal control patients and patients with intermittent exotropia, anisometropic amblyopia, and partially accommodative esotropia. MATERIALS AND METHODS: A total of 133 subjects were included. Stereopsis was measured using the Titmus Stereo test (Stereo Optical Inc., Chicago, IL, USA) and a 3-D stereopsis test with a 15 inch 3-D display laptop, adjusting 3-D parameters of 0 mm horizontal disparity to 15 mm horizontal disparity. RESULTS: When compared with normal controls, the average threshold of the 3-D stereopsis test was significantly reduced for esotropia patients (p<0.001) and for anisometric amblyopia patients (p<0.001), compared to normal controls. No significant difference was observed between normal controls and intermittent exotropia patients (p=0.082). The 3-D stereopsis test was correlated with the Titmus Stereo test (Spearman's rho=0.690, p<0.001). Mean difference in stereoacuity was 1.323 log seconds of arc (95% limits of agreement: 0.486 to 2.112), and 125 (92.5%) patients were within the limits of agreement. CONCLUSION: This study demonstrated that a 3-D stereopsis test with animation is highly correlated with the Titmus Stereo test; nevertheless, 3-D stereopsis with animations generates more image disparities than the conventional Titmus Stereo test. The 3-D stereopsis test is highly predictive for estimating real stereopsis in a 3-D movie theater.

Application of Stereo-Imaging Technology to Medical Field / 대한의료정보학회지

OBJECTIVES: There has been continuous development in the area of stereoscopic medical imaging devices, and many stereoscopic imaging devices have been realized and applied in the medical field. In this article, we review past and current trends pertaining to the application stereo-imaging technologies in the medical field. METHODS: We describe the basic principles of stereo vision and visual issues related to it, including visual discomfort, binocular disparities, vergence-accommodation mismatch, and visual fatigue. We also present a brief history of medical applications of stereo-imaging techniques, examples of recently developed stereoscopic medical devices, and patent application trends as they pertain to stereo-imaging medical devices. RESULTS: Three-dimensional (3D) stereo-imaging technology can provide more realistic depth perception to the viewer than conventional two-dimensional imaging technology. Therefore, it allows for a more accurate understanding and analysis of the morphology of an object. Based on these advantages, the significance of stereoscopic imaging in the medical field increases in accordance with the increase in the number of laparoscopic surgeries, and stereo-imaging technology plays a key role in the diagnoses of the detailed morphologies of small biological specimens. CONCLUSIONS: The application of 3D stereo-imaging technology to the medical field will help improve surgical accuracy, reduce operation times, and enhance patient safety. Therefore, it is important to develop more enhanced stereoscopic medical devices.

Unilateral situs inversus of optic disc associated with reduced binocularity and stereoacuity resembling monofixation syndrome.

Situs inversus of the optic disc is a rare, usually bilateral, congenital embryological abnormality associated with high myopia, optic disc coloboma or tilted optic disc. It is characterized by emergence of the retinal vessels in an anomalous direction with dysversion of the optic disc. In this report we present a 13-year-old boy diagnosed with isolated, unilateral situs inversus of the optic disc associated with reduced binocularity and stereoacuity resembling a monofixation syndrome. The clinicians should be aware of this association and assess the binocularity in patients with unilateral optic disc or macular anomalies. Conversely, patients with reduced binocularity and stereoacuity should be carefully evaluated for macular or optic nerve anomalies, if not associated with strabismus, anisometropia and eccentric fixation. Typical fundus picture, optical coherence tomography and multifocal electro retinogram of the patient would be instructive to a clinician.

Rebuilding of binocular vision after strabismus surgeries for thyroid-associated ophthalmopathy / 中国医学科学院学报

<p><b>OBJECTIVE</b>To evaluate the rule of the rebuilding of binocular vision after surgery in strabismus for thyroid-associated ophthalmopathy.</p><p><b>METHOD</b>The binocular vision was examined and compared in 30 patients before and after strabismus surgeries.</p><p><b>RESULTS</b>The strabismus degrees were 20-80(delta) before surgeries and 2-12(delta) after surgeries. As shown by synoptophores examinations, 19 patients (63.3%) had degree one before strabismus surgeries and the number increased to 28 (93.3%) after the surgeries. Synoptophore fusion area was 0-12(0) [mean (6.1 +/- 4.7)0] before strabismus surgeries and was 0-30(0) [mean (14.4 +/- 5.1)0] after the surgeries (P < 0.001). Nine patients (30%) had stereovision before strabismus surgeries, and the number increased to 22 (73.3%) after the surgeries. Pre-surgery stereoacuity was as follows: none < or = 60", 2 patients 80-200", and 4 patients 300-800"; while the post-surgery stereoacuity was as follows: 4 patients < or = 60", 6 patients 80-200", and 10 patients 300-800" (P < 0.05).</p><p><b>CONCLUSION</b>Strabismus surgeries for thyroid-associated ophthalmopathy can effectively improve ocular movement and rebuilt binocular vision.</p>

Reaching for virtual objects: binocular disparity, retinal motion and the control of prehension

To reach for and grasp an object, its distance, shape and size must be known. In principle, the combination of disparity and motion information could be used to provide this information as the perception of object shape from disparity is biased and the perception of object size from motion is indeterminate. Here we investigate whether the visual system can take advantage of the simultaneous presence of both cues of both cues in the control of reaching and grasping. For both real and virtual objects, peak grip aperture scaled with object size and peak wrist velocity scaled with object distance. Kinematic indices, which reflect distance reached and perceived size, showed clear and systematic biases may be interpreted as arising from the biases in the use of binocular disparity, and the indeterminacy of the information provided by motion. Combining disparity and motion information improved estimates of the width, but not the depth or distance of objects. Overall, these results suggest that accurate metric depth information for the control of prehension is not available from binocular or motion cues, either in isolation or in combination.

Study of multi-factor cognition evoked by binocular disparity / 生物医学工程学杂志

It is the aim of studies in cognitive process to understand how the impressive cognitive capacity of the human mind is uninterruptedly developed and how the process is controlled. We have been focusing attention on the central question with stereoscopic research. A multi-channel EEG data acquisition system is constructed for cognition studies which not only works perfectly in the EEG collection and signal processing of stereoscopic visual evoked potentials(VEP) but also is suitable for investigative and clinical use. We have identified the fact that the processing of stereoscopic depth information is done in the cortical advance functional areas with labeled characteristic signaling of the depth related VEP and the results were shown to be of no difference when compared with the ones of other investigations. We believe, the stereoscopic depth cognition is both a dynamic multi-factor processing process and a consequence of depth perception in advanced cortical areas through biological feedback to the whole process of visual signal processing. It is our novel and significant supposition in the psychophysical study, and the experimental results of the VEP are presented in this article.

Enfermedad de Schilder: a propósito de un caso / Schilder disease: apropos of a case

La ahora denominada Leucodistrofia Adrenocortical tipo Schilder, representa una de las formas más graves de demencia asociada o pérdida visual y auditiva en la edad escolar. Presentamos un caso clínico y radiológicamente característico con el objeto de llamar la atención hacia su existencia y hacia la esperanza de poder ahora realizar diagnóstico pre-natal.

Pulsoterapia com corticóide em fribrose sub-retiniana progressiva / Steroid pulsetherapy in progressive subretinal fibrosis

Uma criança de 10 anos, do sexo masculino, apresentou um caso raro de fibrose sub-retiniana progressiva.Inicialmente apenas o olho direito foi afetado.Sem tratamento, este processo evolui para formaçäo de uma extensa zona de fibrose sub-retiniana na área macular, com severo comprometimento visual.Após um ano e cinco meses apareceram lesöes coroidianas multifocais com deslocamento seroso macular no olho esquerdo, tendo sido precocemente tratadas com corticoesteróides.Houve resoluçäo rápida das lesöes, sem cicatrizaçäo sub-retiniana e o paciente manteve acuidade visual normal neste olho.

Effect of aniseikonia on fusion.

Physiological aniseikonia is the basis of stereopsis but beyond certain limits it becomes an obstacle to fusion. It is not well established as to how much aniseikonia can be tolerated by the fusional mechanism. Different tests under different testing conditions have given a wide range of variation. On the synoptophore we had observed tolerance upto 35% aniseikonia in some cases. Under more physiological conditions on a polaroid dissociation stereoprojector we observed lesser baseline fusional vergences but tolerance in about 70% of the cases upto 30% aniseikonia while 25% could tolerate even 35% aniseikonia. However we realise that these indicate the maximal potential and not the symptom free tolerable limits.

Medial transposition of the lateral rectus muscle in experimentally induced medial rectus paralysis

When the oculomotor nerve is completely paralyzed, the affected eye shows severe outward displacement and poor cosmetic appearance. Past results of many surgical procedures for oculomotor palsy have been generally unsatisfactory. We tried a new surgical approach experimentally, in which the disinserted lateral rectus muscle was used as an adductor by medial transposition of the muscle. Five adult cats underwent disinsertion of the medial rectus muscle of both eyes to induce iatrogenic medial rectus paralysis. The disinserted medial rectus was removed as far back as possible to prevent reattachment. Then, the right lateral rectus muscle was disinserted and passed beneath the superior rectus muscle and resutured to the sclera 4mm superoposterior to the medial rectus insertion site. After excision of the bilateral medial rectus, a large exotropia of an average 47.6 delta (42.0-55.5 delta) was induced. The medial transposition of the right lateral rectus produced an average 36.6 delta (24.8-45.8 delta) correction of the exotropia. A satisfactory cosmetic result was achieved by this procedure.

AC/A Ratio Measured by Modified Gradient Method

A clinical study on the AC/A ratio with 125 normal persons was performed by modified gradient method. AC/A ratio is a convergence response of an individual to a unit stimulus of accommodation. Through many studies on the AC/A ratio, the normal range of the AC/A ratio was 3 delta/D ~ 5 delta/D. The AC/A ratio can be changed by some drugs. The AC/A ratio is high in divergence excessive exotropia, pseudodivergence exotropia and non-refractive accommodative esotropia; on the other hand, the AC/A ratio is low in convergence insufficiency exotropia. Methods for the determination of the AC/A ratio are heterophoria method, gradient method, fixation disparity method. This study was performed by modified gradient method due to easy application. The mean of the AC/A ratios in this study was 4.55 delta/D, and the AC/A ratios ranged from 0.5 delta/D to 9.6 delta/D. 95 percentile ranged from 3.01 delta/D to 6.09 delta/D. The AC/A ratio in this study seems not to be correlated with age, sex and interpupillary distance.

AC/A Ratio Measured by Modified Gradient Method

A clinical study on the AC/A ratio with 125 normal persons was performed by modified gradient method. AC/A ratio is a convergence response of an individual to a unit stimulus of accommodation. Through many studies on the AC/A ratio, the normal range of the AC/A ratio was 3 delta/D ~ 5 delta/D. The AC/A ratio can be changed by some drugs. The AC/A ratio is high in divergence excessive exotropia, pseudodivergence exotropia and non-refractive accommodative esotropia; on the other hand, the AC/A ratio is low in convergence insufficiency exotropia. Methods for the determination of the AC/A ratio are heterophoria method, gradient method, fixation disparity method. This study was performed by modified gradient method due to easy application. The mean of the AC/A ratios in this study was 4.55 delta/D, and the AC/A ratios ranged from 0.5 delta/D to 9.6 delta/D. 95 percentile ranged from 3.01 delta/D to 6.09 delta/D. The AC/A ratio in this study seems not to be correlated with age, sex and interpupillary distance.