A COMPREHENSIVE APPROACH INTO STEREOSCOPIC VISION

Stereopsis (or stereoscopic) vision is the ability to see depth of perception, which is created by the difference in angle of view between both eyes. The first process is known as simultaneous perception. Objects will fall on each corresponding retina and there will be a process of fusion of the two images into one. Then, the brain initiates three-dimensional perception in visual cortex, creating stereoscopic vision. Stereoscopic vision will rapidly develop, especially at the age of 6-8 months of life. Stereoscopic is important in daily activities. There are many stereoacuity tests to evaluate stereoscopic vision. Stereoscopic examinations are based on the principle of haploscope, anaglyph, or polaroid vectograph. There are qualitative and quantitative examination methods to assess stereoscopic vision. Qualitative examinations such as Horizontal Lang Two Pencil test and Synoptophore. Quantitative examination including Contour stereopsis test and Clinical random dot stereopsis test. The inability of the eye to see stereoscopic can be called stereoblindness. This can be affected by amblyopia, decreased visual acuity, or the presence of ocular misalignment. Inability to achieve stereoscopic vision will impact an individual to perform some daily life activities, and lead to an increase in difficulty interacting in the world.

Efficiency and Safety of Binocular Cataract Phacoemulsification

A literature review is presented on the comparative assessment of two options for conducting cataract phacoemulsification — monocular phacoemulsification of cataract, (delayed sequential bilateral cataract surgery, DSBCS) and binocular phacoemulsification of cataract (immediate sequential bilateral cataract surgery, ISBCS). It has been established that to date in the literature there is a sufficient amount of data indicating the positive aspects of ISBCS, associated with faster rehabilitation, better functional results, as well as time, financial, and economic aspects. The safety of ISBCS is determined by the minimum likelihood of postoperative bilateral endophthalmitis with careful selection of patients, the required surgeon qualifications and strict adherence to the surgical protocol. Comparatively, in accordance with the results obtained, postoperative refractive indices, the value of the maximum corrected distance visual acuity, the frequency of complications and the degree of patient satisfaction were the same regardless of whether the bilateral cataract surgery was performed simultaneously or sequentially. The effectiveness of ISBCS is determined by quick rehabilitation, the need for only one pair of glasses, a decrease in visits to the clinic, the absence of anisometropia between operations, as well as only one general anesthesia (if necessary). The experience of clinics where such procedures were carried out shows that after ISBCS, minor refractive errors occur, while they are almost always symmetrical, characterized by a slight deviation from the target refraction and rapid recovery of binocular and stereoscopic vision. In financial terms, in accordance with the calculations carried out, the cost of DSBCS in various countries may be higher than the cost of ISBCS by 10.8–47.9 %. In absolute terms, simultaneous cataract surgery on two eyes (Finland) saved €449 per patient in medical costs and €739 after travel and home care costs were included. Taking into account the cost of lost work time, the savings were €849 per patient. The wider distribution of ISBCS is associated with the approval of the ophthalmological community and insurance companies, as well as the development of standardized teaching materials for practicing ophthalmologists.

Prismatic correction in the presence of acutely acquired esotropia with diplopia

Purpose. To analyze changes in binocular vision functions in patients with acutely acquired esotropia after preoperative correction by prisms. Material and methods. The study included 16 patients with acutely acquired esotropia with diplopia. Depending on the tactics of preoperative case management, two groups were distinguished. Eight patients with acutely acquired esotropia of the Bielshowsky type at the age from 12 to 35 years old (mean age, M±sd – 17.5±1.9 years). This group underwent preoperative prismatic correction of diplopia and the deviation angle, as well as eight patients with acutely acquired esotropia of the Bielshowsky type at the age from 12 to 35 years (18.5±1.9 years). Patients in this group underwent surgery without prior prismatic correction. Fresnel prisms were used to select and assign prismatic correction. The patients were monitored dynamically. Results. In the course of treatment 1 group (prismatic correction followed by surgical correction) according to the indicator of Worth's four-dot test color test, revealed a statistically significant increase in the frequency of value of the binocular single vision (p=0.041), the frequency of the presence of stereovision according to the Fly-test (p=0.013), fusion amplitude in the distance by 1.11 times (p=0.033) and near fusion amplitude by 1.15 times (p=0.003). Significant differences between the groups were observed only in the frequency of stereovision presence according to the Fly-test after treatment, which was 2.0 times higher in group 1 (p=0.041). Conclusion. Prismatic correction in combination with surgical treatment had better curative benefits than surgery itself in improving both binocular and stereoscopic visual functions. Key words: acutely acquired esotropia, diplopia, binocular vision, stereoscopic vision, Fresnel prisms

Influence of Pitch Angle Errors in 3D Scene Reconstruction Based on U-V Disparity: A Sensitivity Study

U-V disparity is a technique that is commonly used to detect obstacles in 3D scenes, modeling them as a set of vertical planes. In this paper, the authors describe the general lines of a method based on this technique for fully reconstructing 3D scenes, and conduct an analytical study of its performance and sensitivity to errors in the pitch angle of the stereoscopic vision system. The equations of the planes calculated for a given error in this angle yield the deviation with respect to the ideal planes (with a zero error in the angle) for a large test set consisting of planes with different orientations, which is represented graphically to analyze the method’s qualitative and quantitative performance. The relationship between the deviation of the planes and the error in the pitch angle is observed to be linear. Two major conclusions are drawn from this study: first, that the deviation between the calculated and ideal planes is always less than or equal to the error considered in the pitch angle; and second, that even though in some cases the deviation of the plane is zero or very small, the probability that a plane of the scene deviates from the ideal by the greatest amount possible, which matches the error in the pitch angle, is very high.

Comparison of the Observation Errors of Augmented and Spatial Reality Systems

Using 3D technologies such as virtual reality (VR) and augmented reality (AR), has intensified nowadays. The mainstream AR devices in use today are head-mounted displays (HMDs), which, due to specification limitations, may not perform to their full potential within a distance of 1.0 m. The spatial reality display (SRD) is another system that facilitates stereoscopic vision by the naked eye. The recommended working distance is 30.0~75.0 cm. It is crucial to evaluate the observation accuracy within 1.0 m for each device in the medical context. Here, 3D-CG models were created from dental models, and the observation errors of 3D-CG models displayed within 1.0 m by HMD and SRD were verified. The measurement error results showed that the HMD model yielded more significant results than the control model (Model) under some conditions, while the SRD model had the same measurement accuracy as the Model. The measured errors were 0.29~1.92 mm for HMD and 0.02~0.59 mm for SRD. The visual analog scale scores for distinctness were significantly higher for SRD than for HMD. Three-dimensionality did not show any relationship with measurement error. In conclusion, there is a specification limitation for using HMDs within 1.0 m, as shown by the measured values. In the future, it will be essential to consider the characteristics of each device in selecting the use of AR devices. Here, we evaluated the accuracies of 3D-CG models displayed in space using two different systems of AR devices.

Transfer of Perceptual Learning From Local Stereopsis to Global Stereopsis in Adults With Amblyopia: A Preliminary Study

It has long been debated whether the analysis of global and local stereoscopic depth is performed by a single system or by separate systems. Global stereopsis requires the visual system to solve a complex binocular matching problem to obtain a coherent percept of depth. In contrast, local stereopsis requires only a simple matching of similar image features. In this preliminary study, we recruited five adults with amblyopia who lacked global stereopsis and trained them on a computerized local stereopsis depth task for an average of 12 h. Three out of five (60%) participants recovered fine global stereoscopic vision through training. Those who recovered global stereopsis reached a learning plateau more quickly on the local stereopsis task, and they tended to start the training with better initial local stereopsis performance, to improve more on local stereopsis with training, and to have less severe amblyopia. The transfer of learning from local stereopsis to global stereopsis is compatible with an interacting two-stage model.

Stereoscopic Visual Perceptual Learning in Seniors

Background: We showed that seniors can improve their stereoscopic ability (stereoacuity) and corresponding reaction time with repetitive training and, furthermore, that these improvements through training are still present even after a longer period of time without training. Methods: Eleven seniors (average age: 85.90 years) trained twice a week for six weeks with dynamic stereoscopic perception training using a vision training apparatus (c-Digital Vision Trainer®). Stereoscopic training was performed in 12 training session (n = 3072) of visual tasks. The task was to identify and select one of four figures (stereoscopic stimuli) that was of a different disparity using a controller. The tests included a dynamic training (showing rotating balls) and a static test (showing plates without movement). Before and after training, the stereoacuity and the corresponding reaction times were identified with the static stereotest in order to determine the individual training success. The changes in respect to reaction time of stereoscopic stimuli with decreasing disparity were calculated. Results: After 6 weeks of training, reaction time improved in the median from 936 arcsec to 511 arcsec. Stereoscopic vision improved from 138 arcsec to 69 arcsec, which is an improvement of two levels of difficulty. After 6 months without training, the improvement, achieved by training, remained stable. Conclusions: In older people, visual training leads to a significant, long-lasting improvement in stereoscopic vision and the corresponding reaction time in seniors. This indicates cortical plasticity even in old age.

Industrial robot programming by demonstration using stereoscopic vision and inertial sensing

Purpose The purpose of this paper is to present a programming by demonstration (PbD) system based on 3D stereoscopic vision and inertial sensing that provides a cost-effective pose tracking system, even during error-prone situations, such as camera occlusions. Design/methodology/approach The proposed PbD system is based on the 6D Mimic innovative solution, whose six degrees of freedom marker hardware had to be revised and restructured to accommodate an IMU sensor. Additionally, a new software pipeline was designed to include this new sensing device, seeking the improvement of the overall system’s robustness in stereoscopic vision occlusion situations. Findings The IMU component and the new software pipeline allow the 6D Mimic system to successfully maintain the pose tracking when the main tracking tool, i.e. the stereoscopic vision, fails. Therefore, the system improves in terms of reliability, robustness, and accuracy which were verified by real experiments. Practical implications Based on this proposal, the 6D Mimic system reaches a reliable and low-cost PbD methodology. Therefore, the robot can accurately replicate, on an industrial scale, the artisan level performance of highly skilled shop-floor operators. Originality/value To the best of the authors’ knowledge, the sensor fusion between stereoscopic images and IMU applied to robot PbD is a novel approach. The system is entirely designed aiming to reduce costs and taking advantage of an offline processing step for data analysis, filtering and fusion, enhancing the reliability of the PbD system.