Visual AcuityLearn more about the vision examinations, the differences between medical professionals, tests and tools used, and how to read an eye report including understanding visual diagnosis implications, visual fields and neurological visual impairments.
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by: 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 Complete Set Bundle + BONUS Resources
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Buy together at a reduced price and get BONUS resources! 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 Note: All products are digital pdf downloads. 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. If you encounter any difficulty, please let me know and I can assist you. *Please contact me if you need to purchase using a purchase order. I am happy to help guide you in the process of adding Teaching Students with Visual Impairments as an approved vendor for your school or program or you can visit the product support page for information on using a PO. |
