VISUAL ACUITYby: Carmen Willings
teachingvisuallyimpaired.com Updated March 11, 2018 Acuity describes the amount of detail the individual sees compared to what a person with normal vision sees. It refers to the sharpness of vision in relation to discriminating detail. It is usually given in Snellen notation. 20/20 is considered 100% or "normal" vision and means that the individual being checked sees at 20 feet what should be seen at 20 feet. The common phrase “20/20 vision” refers to how acuity is measured; the top number, 20, refers to the distance at which the measurement is taken, and the bottom number refers to the distance at which a “normal” eye can see a specific size image. If a person has 20/40 acuity, it means he can see at 20 feet that which someone with “normal” vision can see at 40 feet. The smaller the second number, the more sight a person has. Low vision means a person’s visual acuity is 20/50 or worse. The larger the second number, the less vision a person has. Remember when interpreting an eye report, cc is the abbreviation for with correction and sc is the abbreviation for without (or sans) correction.
How Acuity is Written on Reports:
An acuity provides information on how much the cones and the rods in the eyes are capable of seeing under certain lighting conditions and what their threshold is. Keep in mind that there is no correlation between acuity and visual functioning. Two people with the same visual acuity may have very different visual functioning. Also be aware that vision is a learned response.
Visual acuity is one of the main factors in determining eligibility for school based vision services and whether the student is identified as visually impaired or blind. The clinical eye exam should include formal testing of the student's near and distance acuity when a student is able to participate in formal testing. Visual acuity testing should be conducted with correction (cc) if the student has been prescribed glasses or contacts and also without correction (sc). Having both acuities can be very helpful in understanding the student's vision and whether or not they tolerate wearing the classes or don't as they don't see much improvement. Near Visual Acuity
Near visual acuity indicates the smallest letter, picture or symbol size the student is able to discriminate at a near distance, typically measured at 12 to 14 inches. When an acuity is provided, there should also be a note about the distance the student used in order to identify the symbols. For educational purposes, this impacts a students ability to read various size materials within the classroom, menus, brochures, etc.
Distance Visual AcuityDistance visual acuity indicates the smallest letter, picture or symbol size the student is able to discriminate at a distance, typically measured at 20 feet. For educational purposes, this will indicate whether or not a student can see information presented in the classroom, during assemblies, or demonstration lessons. This will affect the student in extracurricular activities including ability to see a fast food menu, reading street signs, seeing a scoreboard or jerseys at sports games, or locating people at distances. The Snellen chart is the most common eye chart used when assessing the person's visual acuity.
Functional Acuity EstimatesWhen a student is unable to participate in formal testing, an ophthalmologist may provide an estimate of the child's acuity or they may indicate the student Functions at the Definition of Blindness.
Print Comparisons
This page provides environmental print comparisons to the Snellen chart as well as approximation of the student's visual acuity when a student does not respond or cooperate using standard assessments.
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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:
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:
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 Author: Carmen Willings Language: English 
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 Author: Carmen Willings Language: English |
