Book Review: Homonymous Visual Field Defects

Book Review: Homonymous Visual Field Defects Homonymous Visual Field Defects, edited by Dr Karolina Skorkovska, is a welcome addition to the world of ophthalmology, neuro-ophthalmology, neurosurgery, and rehabilitation. Visual field defects have significant practical implications in the day-to-day life of our patients. For example, they may affect their quality of life by affecting their ability to read, drive, or navigate. This may unfortunately have serious consequences on the independence of our patients. A comprehensive monograph on homonymous visual field defects with updates on the recent research in the field would be a welcome addition. The current book fulfills this role extremely well and the prior monograph was written decades ago. It presents comprehensive and evidence-based information regarding the clinical evaluation and management of this relatively common and often distressing sequelae of neurological and neurosurgical conditions. It highlights the practical implications of homonymous visual field defects, especially homonymous hemianopia. Apart from an excellent account of basic pertinent anatomy, and pathophysiology, emphasis is placed on practical aspects including major advances in imaging techniques, rehabilitation including understanding of psychophysical aspects. This book is authored by multiple experts in the field. The most important highlight of the book is its brevity and easy readability. Spanning only about 170 pages, a seriously interested reader may be able to complete this book over a long weekend! The content organization is well thought out. As it is coauthored by several different experts, although some chapters have redundant material, each chapter can be read independently as well. This book is a must for all neuro-ophthalmologists, neurologists who manage strokes, as well as for rehabilitation experts (physiatrists). First chapter covers basic aspects of anatomy of the afferent visual pathway, with emphasis on organization of primary and extra-striate visual cortex. For example, “what and where systems” of the extra-striate system, and blood supply to the visual cortex, are described with illustrations. This chapter provides foundation for understanding and correlation of clinical findings to lesion localization, particularly for cortical visual syndromes. The second chapter provides information on functional aspects of vision: basis of visual field and its defects, basis of stereo-vision. Recent theories and hypotheses from the literature on aspects such as higher order visual processing, and blind sight are provided. For me, primarily a clinician, parts of this chapter were not easy to comprehend at the first attempt. Importance of magnocellular/parvocellular pathways, localization of associated cortical disabilities such as alexia, cerebral achromatopsia, or stroboscopic vision is highlighted. View largeDownload slide View largeDownload slide The third chapter is essentially a clinical summary regarding stroke related homonymous defects: it provides epidemiological data regarding the burden of stroke in general and homonymous field defects and their associated cognitive problems in particular. It is important to note that approximately 20% of patients with strokes may have hemianopsia and over 90% of strokes in the posterior cerebral artery territory have visual field defects. Chapters 3, 4, and 5 would be of extraordinarily importance to all clinicians particularly emergency room physicians, medical students, residents, and fellows in ophthalmology, neurology, and optometry as they highlight the most important aspects of clinical examination techniques, types of field defects, and their associated neurological findings with localization value. Reading difficulties and methods to identify them are dealt in detail, which has great clinical value. Liberal use of magnetic resonance imaging images, colored illustrations, and correlating visual fields reinforces the material well. Chapters 3 and 6 may be of particular significance to neuro-ophthalmologists, neurologists, neurosurgeons, and radiologists as these highlight the utility of the newer imaging techniques in presurgical planning for example. As functional MRI technique permits assessment of brain activity with sensory, motor, or cognitive behavior, studies on aspects such as neuroplasticity and recovery are highlighted. Chapters 7 discuss more recent and advanced understanding of pupillary dysfunction associated with homonymous field defects and their localization value. Eye movements can reveal either abnormal or adaptive patterns in patients with hemi-field defects. In chapter 8, authors note studies in experimental settings and more recently in real life, which support the idea that training of ocular motor behavior may enhance the strategic adaptation to the field deficit. From a patient management perspective, rehabilitative potential and currently available strategies are highlighted in chapters 9, 10, and 11. Rehabilitation strategies are explained, and approaches supporting compensation strategies are recommended, as only they have clear evidence. In another recent review, Raz and Levin1 also noted that compensatory strategies have shown the most promising results. A separate chapter (chapter 9) addresses driving with homonymous hemianopia, a critical issue in modern life. Complex interaction between vision, cognition, motor skills, and environment are highlighted. Interestingly, authors note that drivers, who do not meet legal requirements for driving, may actually be safe drivers in simulated or real environments. This highlights the fact that visual field parameters alone are inadequate to assess driving fitness and more detailed individual assessments may be ideal. This may not be practical because of the cost involved. For readers with specific interest, more extensive discussion on driving with hemianopisa can be found in review by Bowers.2 Spontaneous improvement of visual fields is usually incomplete and may occur in less than 40% of individuals with homonymous hemianopia. Thus, a significant number of individuals will be left with a disabling visual deficit. Agarwal and Kedar3 in a clinically focused review of visual field defects noted that although several methods of rehabilitation (including optical, compensatory, and restitution therapy) are used in practice, none, unfortunately, have shown consistent and significant benefits. This paper also highlights the driving visual field requirements in different states in the USA as well as some countries worldwide. Overall, this book is well–written, and the information is explained in a clear and as simple manner as is possible, making it particularly valuable as an excellent reference whenever a patient presents with homonymous visual field defects. Disclosure The author has no personal, financial, or institutional interest in any of the drugs, materials, or devices described in this article. REFERENCES 1. Raz N, Levin N. Neuro-visual rehabilitation. J Neurol . 2017; 264( 6): 1051- 1058. Google Scholar CrossRef Search ADS PubMed  2. Bowers AR. Driving with homonymous visual field loss: a review of the literature. Clin Exp Optom . 2016; 99( 5): 402- 418. Google Scholar CrossRef Search ADS PubMed  3. Agarwal A, Kedar S. Prognosis and Treatment of Visual Field Defects. Semin Neurol . 2015; 35( 5): 549- 556. Google Scholar CrossRef Search ADS PubMed  Copyright © 2018 by the Congress of Neurological Surgeons This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/about_us/legal/notices) http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Neurosurgery Oxford University Press

Book Review: Homonymous Visual Field Defects

Neurosurgery , Volume Advance Article (6) – May 8, 2018

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Publisher
Congress of Neurological Surgeons
Copyright
Copyright © 2018 by the Congress of Neurological Surgeons
ISSN
0148-396X
eISSN
1524-4040
D.O.I.
10.1093/neuros/nyy084
Publisher site
See Article on Publisher Site

Abstract

Homonymous Visual Field Defects, edited by Dr Karolina Skorkovska, is a welcome addition to the world of ophthalmology, neuro-ophthalmology, neurosurgery, and rehabilitation. Visual field defects have significant practical implications in the day-to-day life of our patients. For example, they may affect their quality of life by affecting their ability to read, drive, or navigate. This may unfortunately have serious consequences on the independence of our patients. A comprehensive monograph on homonymous visual field defects with updates on the recent research in the field would be a welcome addition. The current book fulfills this role extremely well and the prior monograph was written decades ago. It presents comprehensive and evidence-based information regarding the clinical evaluation and management of this relatively common and often distressing sequelae of neurological and neurosurgical conditions. It highlights the practical implications of homonymous visual field defects, especially homonymous hemianopia. Apart from an excellent account of basic pertinent anatomy, and pathophysiology, emphasis is placed on practical aspects including major advances in imaging techniques, rehabilitation including understanding of psychophysical aspects. This book is authored by multiple experts in the field. The most important highlight of the book is its brevity and easy readability. Spanning only about 170 pages, a seriously interested reader may be able to complete this book over a long weekend! The content organization is well thought out. As it is coauthored by several different experts, although some chapters have redundant material, each chapter can be read independently as well. This book is a must for all neuro-ophthalmologists, neurologists who manage strokes, as well as for rehabilitation experts (physiatrists). First chapter covers basic aspects of anatomy of the afferent visual pathway, with emphasis on organization of primary and extra-striate visual cortex. For example, “what and where systems” of the extra-striate system, and blood supply to the visual cortex, are described with illustrations. This chapter provides foundation for understanding and correlation of clinical findings to lesion localization, particularly for cortical visual syndromes. The second chapter provides information on functional aspects of vision: basis of visual field and its defects, basis of stereo-vision. Recent theories and hypotheses from the literature on aspects such as higher order visual processing, and blind sight are provided. For me, primarily a clinician, parts of this chapter were not easy to comprehend at the first attempt. Importance of magnocellular/parvocellular pathways, localization of associated cortical disabilities such as alexia, cerebral achromatopsia, or stroboscopic vision is highlighted. View largeDownload slide View largeDownload slide The third chapter is essentially a clinical summary regarding stroke related homonymous defects: it provides epidemiological data regarding the burden of stroke in general and homonymous field defects and their associated cognitive problems in particular. It is important to note that approximately 20% of patients with strokes may have hemianopsia and over 90% of strokes in the posterior cerebral artery territory have visual field defects. Chapters 3, 4, and 5 would be of extraordinarily importance to all clinicians particularly emergency room physicians, medical students, residents, and fellows in ophthalmology, neurology, and optometry as they highlight the most important aspects of clinical examination techniques, types of field defects, and their associated neurological findings with localization value. Reading difficulties and methods to identify them are dealt in detail, which has great clinical value. Liberal use of magnetic resonance imaging images, colored illustrations, and correlating visual fields reinforces the material well. Chapters 3 and 6 may be of particular significance to neuro-ophthalmologists, neurologists, neurosurgeons, and radiologists as these highlight the utility of the newer imaging techniques in presurgical planning for example. As functional MRI technique permits assessment of brain activity with sensory, motor, or cognitive behavior, studies on aspects such as neuroplasticity and recovery are highlighted. Chapters 7 discuss more recent and advanced understanding of pupillary dysfunction associated with homonymous field defects and their localization value. Eye movements can reveal either abnormal or adaptive patterns in patients with hemi-field defects. In chapter 8, authors note studies in experimental settings and more recently in real life, which support the idea that training of ocular motor behavior may enhance the strategic adaptation to the field deficit. From a patient management perspective, rehabilitative potential and currently available strategies are highlighted in chapters 9, 10, and 11. Rehabilitation strategies are explained, and approaches supporting compensation strategies are recommended, as only they have clear evidence. In another recent review, Raz and Levin1 also noted that compensatory strategies have shown the most promising results. A separate chapter (chapter 9) addresses driving with homonymous hemianopia, a critical issue in modern life. Complex interaction between vision, cognition, motor skills, and environment are highlighted. Interestingly, authors note that drivers, who do not meet legal requirements for driving, may actually be safe drivers in simulated or real environments. This highlights the fact that visual field parameters alone are inadequate to assess driving fitness and more detailed individual assessments may be ideal. This may not be practical because of the cost involved. For readers with specific interest, more extensive discussion on driving with hemianopisa can be found in review by Bowers.2 Spontaneous improvement of visual fields is usually incomplete and may occur in less than 40% of individuals with homonymous hemianopia. Thus, a significant number of individuals will be left with a disabling visual deficit. Agarwal and Kedar3 in a clinically focused review of visual field defects noted that although several methods of rehabilitation (including optical, compensatory, and restitution therapy) are used in practice, none, unfortunately, have shown consistent and significant benefits. This paper also highlights the driving visual field requirements in different states in the USA as well as some countries worldwide. Overall, this book is well–written, and the information is explained in a clear and as simple manner as is possible, making it particularly valuable as an excellent reference whenever a patient presents with homonymous visual field defects. Disclosure The author has no personal, financial, or institutional interest in any of the drugs, materials, or devices described in this article. REFERENCES 1. Raz N, Levin N. Neuro-visual rehabilitation. J Neurol . 2017; 264( 6): 1051- 1058. Google Scholar CrossRef Search ADS PubMed  2. Bowers AR. Driving with homonymous visual field loss: a review of the literature. Clin Exp Optom . 2016; 99( 5): 402- 418. Google Scholar CrossRef Search ADS PubMed  3. Agarwal A, Kedar S. Prognosis and Treatment of Visual Field Defects. Semin Neurol . 2015; 35( 5): 549- 556. Google Scholar CrossRef Search ADS PubMed  Copyright © 2018 by the Congress of Neurological Surgeons This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/about_us/legal/notices)

Journal

NeurosurgeryOxford University Press

Published: May 8, 2018

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