VISUAL FIELDS

By: Carmen Willings
teachingvisuallyimpaired.com

Visual field refers to how great an area a person can see and is measured, in degrees, as an angle. If a person with normal vision looks straight ahead, he should be able to see nearly all of the objects in a half-circle (approximately 160-180 degrees, with an equal area perceived on each side of the nose and 120 degrees on the vertical*). The central one-third of the visual field is seen by both eyes. A visual deficit may be a central field loss, or may occur elsewhere in the visual field. A person is said to have low vision if  they can only see a 40-20 degree field, or less, in their best eye. 

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Central Vision

Central vision (or macula vision), the "what" system, provides color discrimination and allows critical or sharp (exact) seeing tasks. Reading, whether at close or at a distance is a task that requires central vision. This is the vision which is improved when corrective lenses are prescribed. When the macula is not developed sufficiently (as in total cataract) or is deteriorated (as in macula degeneration) corrective lenses are of no value. Seldom can acuity be better than 20/200 if macula or central vision is lost. With this problem a student may wear no glasses, appear to see normally and not be able to do any critical visual task. The following conditions typically affect the central visual field: Macular Degeneration, Cone Dystrophies, and Central Scotomas.

Peripheral Vision

Peripheral vision, the "where" system, provides awareness of movement and serves in dim light and is vital for mobility. 

The following conditions typically affect the peripheral visual field: Chorioretinitis, Glaucoma, Retinal Detachment, and Retinitis Pigmentosa.

Some visual conditions can affect both combined central and peripheral field impairments: Coloboma, Optic Nerve Disorders and Diseases, Optic Atrophy, Optic Nerve Hypoplasia and Septo-Optic Dysplasia, Hemianopsia, and Strokes.

Types of Field Loss

There are different types of visual field loss. 

• A scotoma is a blind spot that may occur at any location in the visual field. 
• Hemanopsia is a condition in which half of the visual field is absent from one or both eyes. 
• In tunnel vision, the visual field is constricted to the central vision. 

Loss of vision in one eye does not reduce vision by 50%. Although there is a loss of vision on the affected side and a general loss of depth perception, it is not a loss of half of the visual system. It is possible to good central vision with limited peripheral vision and to have good peripheral vision with limited central vision. ​

Eccentric Gaze

If a student has scotomas or blind spots, the student could have an eccentric view and need to direct their gaze differently (ex. looking to the right or left or above the object being viewed) and will appear to not be looking directly at an object.

*Ward, Marjorie E., Foundations of Low Vision: Clinical and Functional Perspectives. AFB Press 2004. p. 73 

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TVI's Guide Complete Set Bundle + BONUS Resources

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TVI’s Guide to Teaching the ECC: An Activities Based Curriculum for Teaching Students who are Blind or Visually Impaired
The TVI’s Guide to Teaching the ECC is a digital pdf available for download. It is designed specifically for fellow itinerant Teachers of Students with Visual Impairments (TVI’s), and consists of over 400 activities and topic areas of discussion for instructing students in the Expanded Core Curriculum. The activities are age-neutral and multi-sensory and therefore can meet the needs of the broad range of students served on an itinerant caseload serving. The activities can be individualized to the students various learning modalities and scaffold in order to challenge students but ensure success. Select those activities that align with the student’s learning objects based on the student’s unique visual needs and academic and developmental level. In addition to the core activity areas, each of the 32 Thematic Units incorporates additional unique ECC concepts and skills providing you with a years’ worth of activities. These units are cyclical and can be used repeatedly to help students build on prior knowledge and develop a deeper understanding of concepts. Each unit includes suggestions for activity adaptation associated with the unit. These include lists of objects, possible community-based experiences, environmental print, poems, children & young reader books, children's songs, pop culture songs, movies, and websites.


In addition to the book, the following two supplements are included:
·      TVI’s Guide to the ECC Concept Checklist
·      TVI’s Guide to the ECC Activities Checklist


For complete product details and additional images, visit the TVI's Guide product page.


TVI's Guide to the ECC Product details
·      Digital pdf download: 346 pages (11 pt font)
·      Publisher: Teaching Students with Visual Impairments
·      Author: Carmen Willings
·      Language: English


Visual Efficiency & Near Magnifier Fluency Worksheets: TVI's Guide to the ECC Grab and Go Supplements
The Near Magnifier Fluency Worksheets is a Grab and Go supplement to the TVI's Guide to Teaching the ECC. This workbook is a pdf download that can be printed on demand for use with students. It contains five different types of worksheets for developing visual motor skills and near magnifier fluency skills particularly with the use of a video magnifier. As a companion to the TVI’s Guide to the ECC, the worksheets correspond to each of the 32 ECC Thematic units. The worksheets, along with a list of environmental print for each thematic unit, are designed to help students refine their visual motor skills while reinforcing ECC concepts presented in the thematic units.  


For complete product details and additional images, visit the Visual Efficiency & Near Magnifier Product Page.


Visual Efficiency & Near Magnifier Fluency Worksheet Details:
·      Digital pdf download: 210 pages
·      Publisher: Teaching Students with Visual Impairments
·      Author: Carmen Willings
·      Language: English


Thematic Keyboarding & Braille Fluency and Maintenance Worksheets: A TVI’s Guide to Teaching the ECC Grab & go Supplement
The Thematic Keyboarding & Braille Fluency and Maintenance Grab and Go ECC worksheet packet is a print on demand workbook that contains worksheets in print and simulated braille to use for data collection. Present the student with a hard braille copy and use the worksheets to document accuracy and fluency in reading braille. As a companion to the TVI’s Guide to the ECC, the worksheets correspond to the ECC Thematic activities presented in the curriculum guide. These word lists and sentences will help the student refine their keyboarding or braille reading skills while bridging ECC concepts presented in the thematic units. Although the lists and passages can be produced using a manual braillewriter, you may also copy and paste the passages into any braille translation software for quick production on an embosser. They may also be entered into a typing program such as APH’s Talking Typer to build keyboarding fluency.


For complete product details and additional images, visit the Thematic Keyboarding & Braille Fluency & Maintenance Product Page


Thematic Keyboarding & Braille Fluency Worksheet Details:
·      Digital pdf download: 338-page print and simulated braille worksheets
·      Publisher: Teaching Students with Visual Impairments
·      Author: Carmen Willings
·      Language: English


Thematic Vocabulary Cards and Checklists: Grab & Go ECC Supplement
The Thematic Vocabulary Cards and Checklists Grab and Go ECC supplement is a 446 page pdf downloadable print on demand workbook that includes 2940 vocabulary card on 3 1/2" x 2" templates divided by each of the 32 Thematic Units along with a checklist of each unit words in print and simulated braille. As a companion to the TVI's Guide to the ECC, the vocabulary cards correspond to the ECC Thematic activities presented in the curriculum guide. 


Additional Use:
Teachers of Students with Visual Impairments can have a extremely varied caseloads. It is possible to go several years without having a student on your caseload who requires braille instruction. Like other skills, if you do not practice your braille regularly, it is easy to lose those skills. Use these checklists and cards to maintain your braille skills. Fold the checklist along the line dividing the print from the braille. Choose to either read the print and produce the word in braille using a braillewriter or read the simulated braille and decode it. Finally, these vocabulary cards and checklists may be used with family members or peers who are interested in learning and practicing the braille code.


For complete product details and additional images, visit the Thematic Vocabulary Cards & Checklists Product Page


Thematic Vocabulary Cards and Checklists Details:
·      Digital pdf download: 446-page print on demand resource
·      Publisher: Teaching Students with Visual Impairments
·      Author: Carmen Willings
·      Language: English


BONUS!
Lotto Cards
The LOTTO Cards Grab and Go Supplement includes 37 theme related unit cards along with activity suggestions that support activities within the TVI's Guide to Teaching the ECC.


On My Way File Folder Cards
Print and use these cards to represent locations the student may visit that are related to the current thematic unit. Use these with the On My Way File Folder Game outlined in the TVI's Guide to Teaching the ECC p. 27.

NEW! Access to TVI's Guide Bonus Membership Pages

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