Pickwell's Binocular Vision Anomalies E-Book
Bruce J. W. Evans
- 464 pages
- English
- ePUB (mobile friendly)
- Available on iOS & Android
Pickwell's Binocular Vision Anomalies E-Book
Bruce J. W. Evans
About This Book
Now in a fully up-to-date 6th Edition, Pickwell'sBinocular Vision Anomaliesprovides a practical introduction to binocular vision, offeringcomprehensive theory, how-to clinical guidance, and a summary of current researchin a single, consolidated volume. Ideally suited for both students and clinicians, this bestselling text serves as anaccessible, evidence-based referencewhen faced with binocular vision or pediatric challenges.
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Coversroutine examinations and testing protocols, including CISS questionnaire, cover test, foveal suppression, fixation disparity, four prism diopter base out test, Lindblom's method, and double Maddox rod test.
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Includesnumerous video clipsof key testing procedures, including new clips on Mallett fixation disparity test and fusional reserve testing, as well as an interactivevideo quizto help you test your knowledge.
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Featuressweeping content updatessuch as the latest information on 3-D displays, therapeutic uses of computer games and virtual reality for vision therapy, computerized testing methodologies, binocular and accommodative mechanisms associated with myopia, updated prescribing criteria, therapeutic use of contact lenses, detection of pathology associated with strabismus, drugs causing diplopia, and the evidence-based treatment of convergence insufficiency syndrome and amblyopia.
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Containshelpful study features throughout, including Clinical Key Points boxes, step-by-step test routines, typical features of extraocular muscle palsies and syndromes, and Case Study boxes that cover important clinical and legal scenarios, and new boxes that summarize testing procedures for each of the main binocular vision tests.
Frequently asked questions
Information
Nature of Binocular Vision Anomalies
Abstract
Keywords
Introduction
- 1. The anatomy of the visual apparatus.
- 2. The motor system that coordinates movement of the eyes.
- 3. The sensory system through which the brain receives and integrates the two monocular signals.
- 1. Anatomy. Abnormalities in the anatomy of the visual system can be either developmental, occurring in the embryological development of the bony orbit, ocular muscles, or nervous system, or acquired through accident or disease.
- 2. Motor system. Even if the motor system is anatomically normal, anomalies can occur in the functioning which can disturb binocular vision or cause it to break down. These may be due to disease, or they may be malfunctions of the physiology of the motor system. For example, excessive accommodation due to uncorrected hypermetropia can result in excessive convergence due to the accommodation–convergence relationship. This is a frequent cause of binocular vision problems. Examples of disease affecting the motor system are haemorrhages involving the nerve supply to the extraocular muscles, changes in intracranial pressure near the nerve nuclei, or pressure on the nerves or nerve centres from abnormal growths of intracranial tissue. Such conditions require urgent medical attention to the primary condition and early recognition is therefore essential. The investigation for this type of pathology is discussed in Chapter 17.
- 3. Sensory system. Anomalies in the sensory system can be caused by such factors as a loss of clarity of the optical image in one or both eyes, an image larger in one eye than the other (aniseikonia), anomalies of the visual pathway or cortex, or central factors in the integrating mechanism. The ultimate goal of binocularity is stereopsis (DeAngelis, 2000), which improves motor skills at near distances (O'Connor, Birch, Anderson, & Draper, 2010), but has a minimal effect beyond about 40 m (Bauer, Dietz, Kolling, Hart, & Schiefer, 2001).
Stereopsis is not the only benefit from binocularity: there is a binocular advantage in terms of visual acuity and contrast sensitivity. The benefit in terms of contrast sensitivity is underestimated in the ideal conditions of visual acuity testing. For example, when driving in snow or with a dirty windshield, binocularity markedly outperforms monocular vision (Otto, Bach, & Kommerell, 2010). Binocular performance is better than monocular at a wide range of tasks (Sheedy, Bailey, Buri, & Bass, 1986). Difficulties in the coordinating mechanism of the motor system can also be accompanied by adaptations and anomalies in the sensory system, such as suppression, abnormal retinal correspondence, or amblyopia. These may occur to lessen the symptoms caused by the motor anomaly, as adaptations of the sensory system.