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Cortical Visual Loss
Published in Vivek Lal, A Clinical Approach to Neuro-Ophthalmic Disorders, 2023
This is a deficit in attention. Classically, the term means that patients cannot pay attention to more than one object at a time. When severe, it is almost as bad as being blind or having tunnel vision, and patients may express their symptoms in those terms and behave as if blind. This underscores the fact that perception is as much about attention as it is about vision.
The retina, optic nerve and vitreous humour
Published in Mary E. Shaw, Agnes Lee, Ophthalmic Nursing, 2018
Retinitis pigmentosa is a hereditary degeneration of the retinal nerve cells affecting one in 2500. The hereditary aspect is variable, resulting in varying degrees of severity. The autosomal and X-linked recessive forms are severe, with symptoms starting in teenage years. The auto-somal dominant form is less severe, with symptoms occurring in later adult life. The rods are slowly destroyed, initially affecting the peripheral retina causing night-blindness. Eventually, the whole retina is affected when tunnel vision results.
Stress, Perceptual Distortions, and Human Performance
Published in Darrell L. Ross, Gary M. Vilke, Guidelines for Investigating Officer-Involved Shootings, Arrest-Related Deaths, and Deaths in Custody, 2018
Darrell L. Ross, Randall L. Murphy
First, the most common perceptual distortion experienced by officers involved varying aspects of vision. Every study reported that the officer experienced “tunnel vision” and the frequency of experience averaged 54 percent of the incidents. Tunnel vision, referred to as selective attention, is the loss of peripheral vision and the field of vision is narrowed. In many incidents, the officer may lose about 75 percent of the peripheral vision, allowing the ability to keenly cue into the threat, but be oblivious to actions going on around him or her. This would be consistent with Breedlove's (2013) findings that when the SNS is activated in response to a survival stress encounter, an officer will lose about 70 percent of his or her vision. Breedlove (2013) reports that when the SNS is activated, vasoconstriction to the blood vessels on the periphery of the retina occurs, which results in narrowing of the peripheral field known as tunnel vision.
How Do Patients Feel About Visual Field Testing? Analysis of Subjective Perception of Standard Automated Perimetry
Published in Seminars in Ophthalmology, 2021
Núria Mendieta, Joel Suárez, Noelia Barriga, Roger Herrero, Begoña Barrios, Mercè Guarro
These results demonstrate that patients’ perception is a poor predictor of VFT results. It seems unlikely that their subjective perception could be an indicator of the severity of their visual disability. Hoste18 suggests that VF defects are probably filled in by the brain using information received from the surrounding retina, making the patient unable to notice their visual problem until a late disease stage. This unawareness explains the proportion of patients in our study with objective damage who did not self-report damage. In a 50-patient study, Crabb et al. showed that 26% of patients with VF damage were unaware of their vision loss. Blurred or missing patches were reported by 70% of patients, while tunnel vision was only described by 4% of patients.19 These results suggest that glaucoma patients do not perceive vision loss according to their VF scotomas.
Psychosocial determinants associated with quality of life in people with usher syndrome. A scoping review
Published in Disability and Rehabilitation, 2020
Marine Arcous, Olivier Putois, Sophie Dalle-Nazébi, Sylvain Kerbourch, Anaelle Cariou, Ines Ben Aissa, Sandrine Marlin, Rémy Potier
Usher Syndrome is an autosomal recessive condition characterized by partial or total auditory and visual deficit. Auditory deficit is almost always congenital and due to the sensorineural hearing loss, whereas visual deficit is inevitably progressive and caused by retinitis pigmentosa. Sensorineural hearing loss is due to abnormalities of the inner ear, auditory pathways, and cortical hearing centers, such as damage of nerve and some cochlear hair cells. Sensorineural hearing loss accounts for about 90% of hearing loss reported. When hair cells and neurons are damaged or destroyed, they do not naturally regenerate and cause irreversible hearing loss. Therefore, this type of deafness is generally permanent and can be mild, moderate, severe, profound, or total [3]. On the other hand, retinitis pigmentosa is characterized by a progressive loss of photoreceptors, associated with pigment epithelium dysfunctions. Retinitis pigmentosa leads to chronic inflammation of the retina, which produces black patches affecting darkness vision creating night-blindness (the inability to see at dusk), which results in “tunnel vision” during teenage years. The size of the tunnel vision is variable, usually representing between 5 and 10 degrees of the visual angle [4]. Dischromatopsy, usually known as “colorblindness,” also occurs sometimes [5]. Additional vestibular dysfunctions appear in some patients, leading to equilibrium disorders [6].
Clinical and genetic study on two Chinese families with Wagner vitreoretinopathy
Published in Ophthalmic Genetics, 2020
Huajin Li, Hui Li, Lizhu Yang, Zixi Sun, Shijing Wu, Ruifang Sui
The proband’s 46-year-old affected mother (F1-II2) had poor vision since childhood and felt more comfortable in dim light. At the age of 30, she underwent cataract surgery in both eyes. Her BCVA was 20/50 (OD) and 20/200 (OS) when she was examined in our clinic. She presented color vision defect OU. The anterior segments were normal with intraocular lenses. The dilated fundus examination revealed an optically empty vitreous with vitreous veils in the inferior periphery retina. Diffused chorioretinal atrophy with dark pigment clumps scattered around retina (Figure 2(B)). Thin inner retina with loss of ellipsoid zone, interdigitation zone, and choriocapillaris was documented with OCT (Figure 2(E)). Ocular B-ultrasonography revealed vitreoretinal membranes in both eyes (Figure 2(H)). FAF displayed circular and irregular hyperfluorescence in the posterior pole, round and geographic hypofluorescence patches around optic disc and in the mid-periphery region (Figure 3(E)). Visual field testing showed tunnel vision around 7-degree OD and inferior-central vision around 15 degrees (Figure 3(F)). ERG recordings showed moderately reduced rod and cone responses (Figure 4).