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.
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 to Teaching the ECC: An Activities Based Curriculum for Teaching Students who are Blind or Visually Impaired
$50.00
Written specifically for fellow itinerant Teachers of Students with Visual Impairments (TVI’s), this book 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.
The core activities listed in the Activity section can be adapted to each thematic unit. These include:
Object Characteristic Activities
Quantity & Number Concepts
Time Concept Activities
Environment & Job Awareness Activities
Listening Skills Activities
Reading Foundation Activities
Reading Fluency Activities
Braille Basics Activities
Writing Activities
Tactual Efficiency Activities
Developing Skillful Hands Activities
Visual Efficiency Activities
Optical Device Instruction Activities
Recipe Activities
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.
Unique Concepts within the Units include:
Self Advocacy Activities (e.g. advocating for safe classroom, presenting to class on visual impairment, requesting help and more)
Social Skills Activities (e.g. Being bullied or teased, giving and receiving compliments, body language, "I" messages when upset and more)
Recreation & Leisure Activities (e.g. exploring interest areas, getting involved in clubs and sports, playing games, and more)
O&M Support Activities (e.g. Suggestions for community based experiences, dog guide information, locations in the school, bioptics, ride sharing, traffic signs, and more)
Independent Living Skill Activities (e.g. chores, being responsible, using tools, recipe suggestions, hygiene, staying healthy, labeling foods and products, and more)
Sensory Efficiency Activities (e.g. unique sensory experiences related to the unit, unique optical device activities, and more)
Compensatory Activities (e.g. organizing materials, study habits, and many unique concepts related to the unit)
Career & Vocational Activities (e.g. job awareness, completing applications, job task suggestions, and more)
Although the intended audience of this resource is fellow Teachers of Students with Visual Impairments, special education teachers may find these activities beneficial to the students in their classrooms as the activities are multisensory and include life skills and concepts needed by all students. This resource, however, is not intended to take the place of a Teacher of Students with Visual Impairments (TVI). Readers are advised to consult their own TVI’s regarding instruction in the ECC and the unique visual needs of the student’s served in their programs.
Note: This curriculum is a digital pdf download. Once you make your purchase you will be directed to an order confirmation page where you will find the download link. This download will also be included on the receipt sent to the email address you provide. The pdf download can be found directly under the order number.
Each download is intended for single instructor use per copyright. Thank you for helping me preserve the content and not distributing copies to third parties.
Product details
Digital pdf download: 364 pages (11 pt font)
Publisher: Teaching Students with Visual Impairments
Visual Efficiency & Magnifier Fluency Grab & Go ECC Supplements
$20.00
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 supplement 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.
Visual Efficiency & Near Magnifier Fluency Worksheet Details:
Digital pdf download: 210 pages
Publisher: Teaching Students with Visual Impairments
