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Three-dimensional ultrasound
Published in Peter R Hoskins, Kevin Martin, Abigail Thrush, Diagnostic Ultrasound, 2019
Peter R Hoskins, Tom MacGillivray
For stereoscopic viewing to work with ultrasound there must be sufficient contrast between the objects of interest and surrounding tissue. Some anatomical structures such as cysts, ventricles and abscesses as well as lesions surrounded by low echogenic tissue, i.e. some tumours and haematomas, provide good contrast in ultrasound images and are therefore well suited. Breast tumours and cardiac structures such as the mitral valve are also suitable for stereo display. In obstetrics stereoscopic viewing improves visibility of primary features such as fetal skull and spine (Nelson et al. 2008). Augmented stereoscopic vision has applications in surgery as it allows the combination of radiographic data from different sources (e.g. ultrasound, CT and MRI) with the surgeon's vision (Gronningsaeter et al. 2000).
Early detection and prevention of vision defects
Published in Micha de Winter, Mariëlle Balledux, José de Mare, Ruud Burgmeijer, Screening in Child Health Care, 2018
Micha de Winter, Mariëlle Balledux, José de Mare, Ruud Burgmeijer
Next to the tests discussed above, Ehrlich et al. (1983) mention tests for stereoscopic vision (notably the Random Dot Stereogram (RDS)) as one of the best tests for the detection of amblyopia. When this test is used as an amblyopia screening test the basic assumption is that stereoscopic vision is one of the first visual functions lost through amblyopia. In the Netherlands too, research has been conducted into the use of such tests (for instance the TNO stereo test) for the early detection of amblyopia (Walraven & Janzen 1983, Tan-Tan 1988, Lie 1986); so far this has mainly been targeted at older pre-school children (from about 4 years). The study by Walraven and Janzen among 730 children aged 4—18 years (1983) showed the TNO test to have a sensitivity of 100% and specificity of 93% in regard to the detection of amblyopia. According to Ehrlich et al. (1983) such a test can also be used with younger children. They mention two surveys (Reinecke & Simons 1974, Simons & Reinecke 1978) in which the RDS was used with pre-school children. From these studies, it appears that the test is easy to carry out, is effective and that there is no problem in getting the children’s cooperation. Considering the positive results with similar tests in other countries, it is recommended to investigate the applicability of this method within preschool Child Health Surveillance.
Principles of Skeletal Growth
Published in D. Dixon Andrew, A.N. Hoyte David, Ronning Olli, Fundamentals of Craniofacial Growth, 2017
The term “base of the skull” denotes that part which connects the skull vault and the facial skull. Its defining feature is the flexure of the cranial base, measured by ascertaining the flexion angle (Figure 1.24). In comparison to the skulls of quadrupeds, the skull base angle in humans is relatively small. This is believed to be mainly due to the upright posture, the increase in volume of the brain as well as the frontal positioning of the eyes, a consequence of stereoscopic vision (Figure 1.25). The postnatal changes in proportion to the human cranium also result in a smaller basal flexion angle.
The Effects of Binocular Visual Function Training after Concomitant Exotropia Surgery
Published in Current Eye Research, 2023
Jing Chen, Jin Xu, Huili Jia, Jing He, Zhengyang Tao, Ping Huang, Huahong Zhong, Hongwei Deng
In this study, the distant and near stereo acuity of patients in the training and control groups were all recovered at the end of the follow-up period, but the recovery of the distant and near stereo acuity of patients in the training group was significantly higher than in the control group at this point in time. Existing studies have shown that patients with partially recovered binocular vision also had better eye position control. Some scholars believe that only a small number of patients will recover a degree of stereoscopic vision in the natural environment after strabismus surgery, while most patients still retain abnormalities in stereoscopic vision or failure in the reconstruction of stereoscopic vision.11 For patients with concomitant exotropia, particularly intermittent exotropia, central stereoscopic vision developed in the early stage. Despite preoperative strabismus and no stable normal eye position, and in some cases, even no stereoscopic vision, normal binocular parallax stimulation can quickly help to recover stereoscopic vision in the visual cortex when the normal eye position remains stable after surgery. At this stage, it is very important to improve the visual quality and prevent the recurrence of strabismus in patients to strengthen postoperative binocular visual training.
Endoscopic versus microscopic type-I cartilage tympanoplasty for anterior perforation – a comparative study
Published in Acta Oto-Laryngologica, 2021
Dipesh Shakya, Arun KC, Nirmala Tamang, Ajit Nepal
The microscope has been a widely used tool for the otological procedure and still considered as the gold standard in this field. It provides the main advantage of bimanual handling along with stereoscopic vision, better depth perception, and excellent magnification [11]. However, due to its straight line of vision, it has a drawback of the inability to look around the nooks and corners of the middle ear cavity like sinus tympani, retrotympanum, epitympanum and tensor fold area [2,7,12]. Anterior perforation especially in cases with narrow canal or bony overhang needs postauricular approach and/or canaloplasty to perform the tympanoplasty. Nevertheless, tympanoplasty for anterior perforation is still considered as a high-risk case. The reasons for the lower success rate in the closure of anterior TM perforation are insufficient visualization, technically challenging procedure, decreased graft viability due to poor vascularization, inadequate anterior membrane remnant, and poor stabilization [13].
Effects of muscular injuries on the technical and physical performance of professional soccer players
Published in The Physician and Sportsmedicine, 2020
Javier Portillo, Pablo Abián, Bibiana Calvo, Víctor Paredes, Javier Abián-Vicén
In each stadium, six cameras were installed at roof height, 20 m apart. These cameras are divided into two boxes (3 + 3), and function in a similar manner to the human eye providing stereoscopic vision. The pitch is divided into three zones and a camera from each box is assigned to track each zone. The tracking system used was developed by TRACAB, and detects objects by analyzing images. The images were obtained by the cameras that cover the pitch, and the position of the cameras was fixed during the match. The system detected the position of objects in three dimensions using stereo images, i.e. two simultaneous views of the pitch from slightly different angles. All this image processing was done on a computer installed in the stadium. The signals received from the cameras were recorded at a frequency of 25 Hz. The use of this methodology and materials for the analysis of sport performance has been used previously [25–27]