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Clinical Examination in Neuro-Ophthalmology
Published in Vivek Lal, A Clinical Approach to Neuro-Ophthalmic Disorders, 2023
Selvakumar Ambika, Krishnakumar Padmalakshmi
Visual field analysis is one of the fundamental tests to evaluate the afferent visual system. Various methods to access the visual fields were developed over the years. Visual field analysis helps in documentation and quantification of the field defect, localizing the lesion along the afferent visual pathways and also useful in follow up over time.
Assessing Paediatric Development in Psychiatry
Published in Cathy Laver-Bradbury, Margaret J.J. Thompson, Christopher Gale, Christine M. Hooper, Child and Adolescent Mental Health, 2021
The visual system can be split into three sections: the anterior visual system, the primary visual cortex and the associative visual processing streams (the ventral/parietal and the dorsal/temporal streams). The anterior visual system incorporates the optic globe, the retina and its histological components (rod and cone receptor cells), amacrine and horizontal cells, bipolar cells and the retinal glial cells, and up to the formation of the optic nerve.
Vision and Higher Cortical Function
Published in Andrei I. Holodny, Functional Neuroimaging, 2019
Sonia Gill, John Ulmer, Edgar A. DeYoe
Focal pathology or treatment-induced damage to the visual system can produce visual field scotomata that significantly impact a patient’s ability to use vision in their daily activities. Vision deficits can prohibit the individual from reading or driving and may prevent employment, thereby significantly impacting the individual’s quality of life. The severity of this impact can vary with the portion of the visual field that is damaged. Involvement of the central 5°, especially in the right field, can be particularly devastating for reading and activities requiring high acuity (44–46). Deficits in more peripheral portions of the field, however, can go largely unnoticed or may be interpreted incorrectly by the patient as a nonvisual disorder [e.g., “I’m getting clumsier since I keep bumping into things” (that are not seen in the peripheral field.)] The actual impact for each individual will depend on his or her particular lifestyle and occupation (librarian—central vision, truck driver—central + peripheral vision). Consequently, some patients may tolerate peripheral field loss better than others. In such case, mapping the peripheral versus central field may allow a more aggressive, rather than less aggressive, resection. In addition to scotomata, functionally selective visual deficits due to damage of extrastriate or parietal areas also can impact quality of life. Prosopagnosia or word-form agnosia can be challenging for patients and their families, while severe deficits in visual attention (neglect) can be debilitating (35), with loss of both employment and overall independence.
Assessing lesion location, visual midline perception and proprioception may assist outcome predictions for people affected by lateropulsion
Published in Disability and Rehabilitation, 2023
Unlike the vestibular and proprioceptive systems, inputs from the eyes do not reach the medulla or pons. Instead, visual inputs travel via the optic tract mostly to the lateral geniculate nucleus of the thalamus, and from there to the primary visual cortex in the occipital lobe [9]. From the primary visual cortex, visual inputs undergo multimodal processing in the dorsal (for spatial location) and ventral (for object recognition) streams [9]. Of particular interest is the dorsal stream which terminates in the inferior parietal lobe, the cortical destination of proprioceptive and vestibular inputs. Due to the segregation of the visual system, the inferior parietal lobe is the only cerebral cortex where sensory integration of inputs from all three modalities takes place. In addition, the non-dominant inferior parietal lobe plays a pivotal role in multimodal sensory processing related to spatial location, thus it may be a key cortical region to consider in relation to lateropulsion.
Binocular vision disorders in a geriatric population
Published in Clinical and Experimental Optometry, 2022
Hassan Hashemi, Payam Nabovati, Abbas Ali Yekta, Mohammadreza Agha Mirsalim, Shokoofeh Rafati, Hadi Ostadimoghaddam, Mehdi Khabazkhoob
Binocular vision disorders are a group of visual system abnormalities that impair visual performance by affecting clear single binocular vision.1 Various studies have reported a considerable prevalence of heterophoria in children and pre-presbyopic young adults. Accordingly, the prevalence of heterophoria has been reported in a wide range from 9.9 to 61.4% (median prevalence: 22.6%)2–15 this variability is mainly due to differences in diagnostic criteria and testing methods.1 According to a recent review in which the studies were also mostly related to children and young adults, the estimated global pooled prevalence of strabismus was 1.9%; 1.8% in subjects below 20 years and 3.3% in subjects above 20 years.16 Age-related changes in binocular vision status and the prevalence of binocular vision disorders in the elderly have received less attention.17
A Story of Discovery and Change: What We Learned from Studying Nystagmus in Infancy and Childhood
Published in Journal of Binocular Vision and Ocular Motility, 2022
The three broad areas of visual system treatment include medical, optical, and surgical. Common, standard visual system treatment of patients with INS includes correction of refractive errors with spectacles, amblyopia treatment, strabismus surgery, low vision devices, and sunglasses. Correction of significant refractive errors with spectacles and importantly contact lenses in children with nystagmus is the single most powerful therapeutic intervention for improving vision and visual function in these patients. Refractive etiologies of decreased “vision” include either one or a combination of conditions, e.g., myopia, hyperopia, astigmatism, and anisometropia. Although treatment of refractive error is standard of care, the use of contact lenses provides additional advantages. These include improved optical quality of contacts, movement of the contact lens with the eye (allowing some use of anomalous head positioning without the prismatic effect or obstruction of the visual field by the spectacle lenses or frame, respectively), tinting of the contact to treat photophobia and light interference, and finally, additional damping of the nystagmus due to the physical contact of the lens with the ocular surface.