Snellen Chart:
Participants:
Children from all grades
Equipment:
Snellen Chart (and/or Tumbling E or Number/Picture Charts), Dixie Cups, masking tape (for marking of line- to be 20 feet from chart), and pens for screeners to use for completing forms.
Purpose:
Chart used to measure visual acuity- the measure of how well a person can see at a set distance. Vision is identified based on the smallest line an individual can successful read while standing 20 feet away. Thus the number “20” is the constant numerator.
Types of Snellen Charts:
- Letter Chart
- Tumbling E Chart- used for individuals who cannot read, have the individual use their hand to indicate the direction of the letter E. (For example right, left, up, or down)
- Number or Picture Chart- used for young individuals who cannot read. Have the individual verbalize the common shape or picture seen in each line (i.e. heart, house, etc.).
Pre-Screening:
Verify the student’s name matches the name on the screening form. Ask the participant if they wear contacts/glasses. If yes inquire if they have their contacts/glasses with them at today’s screening and select the appropriate box in section 1 of the form. (If they usually have contacts/glasses but are NOT wearing them today select the appropriate box in section 4 of the form). As this will warrant a re-screen.
Verbal Instructions:
Instruct the individual to stand 20 feet away from the chart. Tell them to stand up tall and cover their right eye (may keep it open) with the Dixie cup. Starting with the top row (large E) have the participant read aloud the letters. The smallest row that can be read accurately indicates the visual acuity in that specific eye. For example if they can read the 40 foot line their vision is 20/40. Now instruct the individual to use the Dixie Cup to cover their left eye (may keep it open). Starting with the top row (large E) have the participant read aloud the letters. The smallest row that can be read accurately indicates the visual acuity in that specific eye. For example if they can read the 60 foot line their vision is 20/60. Now have the individual dispose of the Dixie cup in the nearby trash can and read aloud with both eyes open the letters the chart starting with the top row (large E). Record the visual acuity in the assigned box/section. For the purpose of this screening a visual acuity of 20/40 or larger warrants a referral.
**Passing Criteria:
To pass a line on the visual acuity chart, a child must be able to identify at least 75 percent of the letters presented on that line (e.g., on a line with six letters, only one error is acceptable). b. The recorded visual acuity is the smallest line of letters that can be read with 75 percent accuracy:
1) Allow no misses on lines with 1-3 letters.
2) Allow one miss on lines with 4-7 letters.
3) Allow two misses on lines with 8-11 letters.
All children must be able to read the 20/30 (pass) line with each eye separately to pass a Distance Visual Acuity screening
**If the tumbling E or number/picture chart is being utilized follow the same instructions but rather than reading aloud the letters have them either:
- Use their hand to indicate the direction of the letter E. (For example right, left, up, or down)
- Verbalize the common shape or picture seen in each line (i.e. heart, house, etc.).
Snellen Chart with +2.50 Diopter Glasses:
Participants:
Children from all grades
Equipment:
Snellen Chart (and/or Tumbling E or Number/Picture Charts), 2.50 diopter glasses, dixie cups, masking tape (for marking of line- to be 20 feet from chart), and pens for screeners to use for completing forms.
Purpose:
To determine if the participant is able to read the chart better while wearing the Diopter Glasses. If the participant is able to correctly recognize greater than 50% of the letters (or E if using Tumbling E or pictures if using Number to Picture chart) on the 20/30 line this constitutes a non-passing result. This result means that the participant’s vision is better while wearing the diopter glasses, and thus would benefit for additional screening for glasses/contacts.
Verbal Instructions:
Instruct the individual to stand 20 feet away from the chart. Tell them to stand up tall and place the diopter lenses on. Ask the participant to read aloud the letters (or pictures) on the 20/30 line. Record the results in the assigned box/section. For the purpose of this screening if the participant is able to correctly identify more than 50% of the letters on the 20/30 line that indicates a non-passing result and thus warrants a referral.
**Passing Criteria:
To have “passed” this portion of the Snellen exam the individual must NOT be able to successfully identify more than 50% of the letters on the 20/30 line while wearing the diopter glasses.
**If the tumbling E or number/picture chart is being utilized follow the same instructions but rather than reading aloud the letters have them either:
- Use their hand to indicate the direction of the letter E. (For example right, left, up, or down)
- Verbalize the common shape or picture seen in each line (i.e. heart, house, etc.).
Near Vision with RosenBaum Pocket Vision Screener:
Participants:
Children from all grades
Equipment:
Rosenbaum pocket vision screener, dixie cups, and pens for screeners to use for completing forms.
Purpose:
Chart used to measure near visual acuity- the measure of how well a person can see up close. This test can also detect if an individual has excessive hyperopia/hypermetropia (farsightedness)
Pre-Screening:
Verify the student’s name matches the name on the screening form. Ask the participant if they wear contacts/glasses. If yes inquire if they have their contacts/glasses with them at today’s screening and select the appropriate box in section 1 of the form. (If they usually have contacts/glasses but are NOT wearing them today select the appropriate box in section 4 of the form). As this will warrant a re-screen.
Verbal Instructions:
Instruct the individual to extend their arm out 14 inches and hold the card in their right hand in front of their face. Tell them to stand up tall and cover their right eye (may keep it open) with the Dixie cup. Instruct the individual to start reading aloud from the 20/70 line. Have them read aloud left to right the letters. If they are unable to read have them, instruct them to move up a line and so on; until they can correctly identify a line. If they are able to read the 20/70 line move downward and continue until they can no longer correctly identify the numbers. The smallest row that can be read accurately indicates the visual acuity in that specific eye. Now instruct the individual to use the Dixie Cup to cover their left eye (may keep it open). Instruct the individual to start reading aloud from the 20/70 line. Have them read aloud left to right the letters. If they are unable to read have them, move up a line and so on; until they can correctly identify a line. If they are able to read the 20/70 line move downward and continue until they can no longer correctly identify the numbers. The smallest row that can be read accurately indicates the visual acuity in that specific eye. Now have the individual dispose of the Dixie cup in the nearby trash can and read aloud with both eyes open the letters on the card starting with row 20/70. Have them read aloud left to right the letters. If they are unable to read have them move up a line and so on until they can correctly identify a line. If they are able to read the 20/70 line move downward and continue until they can no longer correctly identify the numbers. Record the visual acuity in the assigned box/section. For the purpose of this screening a visual acuity of 20/40 or larger warrants a referral.
**Passing Criteria:
To pass a line on the visual acuity chart, a child must be able to identify at least 75 percent of the letters presented on that line (e.g., on a line with six letters, only one error is acceptable). b. The recorded visual acuity is the smallest line of letters that can be read with 75 percent accuracy:
1) Allow no misses on lines with 1-3 letters.
2) Allow one miss on lines with 4-7 letters.
3) Allow two misses on lines with 8-11 letters.
All children must be able to read the 20/30 (pass) line with each eye separately to pass a Near Visual Acuity screening
**If the tumbling E or X0 portion of the card is being utilized follow the same instructions but rather than reading aloud the letters have them either:
- Use their hand to indicate the direction of the letter E. (For example right, left, up, or down)
- Verbalize the letter as an X or O.
Stereopsis: The Fly Stereo Acuity Test
Participants: Children from all grades
Equipment: The Fly Stereo Acuity Booklet, polarized viewers (pediatric/adult sized appropriate for student), pens for screeners to use for completing forms.
Purpose: The booklet is used to rapidly test for amblyopia, strabismus and other binocular acuity problems by using stereopsis -depth perception. Specifically the child’s ability to perceive spatial relationships, distances between objects, and three dimensions.
Pre-Screening: Verify the student’s name matches the name on the screening form. Ask the participant if they wear contacts/glasses. If yes inquire if he/she have their contacts/glasses with him/her at today’s screening and select the appropriate box in section 1 of the form. (If he/she usually have contacts/glasses but are NOT wearing them today select the appropriate box in section 4 of the form). As this will warrant a re-screen.
Verbal Instructions: Ask the test subject to place the polarized viewers on his/her face, over the top of prescription glasses if worn. Open the test booklet so only page 1 can be viewed. Hold the test booklet approximately 16 inches from the test subject, at eye level of the test subject. If there is a glare or reflection on the test booklet page, try tilting the booklet to eliminate glare or reflection. Ask the test subject if he/she can see the fly. The wings of the fly should appear to be “popping out.” Ask the test subject to pinch the wings of the fly. Observe whether the test subject’s fingers pinch above the page or touch the page. If the test subject is unable to see the 3-D image, ask the test subject to identify the “L” & “R” at the bottom of the page. If the test subject is unable to perform this task, he/she is untestable.
**Passing Criteria: To pass the test subject must be able to pinch the wings of the fly, above the test booklet without touching the page of the test booklet.
Color Testing with Ishihara’s Design Charts:
Participants:
Children from all grades
Equipment:
Ishihar’s design charts, cotton tip applicators, and pens for screeners to use for completing forms.
Purpose:
Colored cards that are used to detect an individual’s perception of color; furthermore to determine if an individual is color blinded.
Pre-Screening:
Verify the student’s name matches the name on the screening form. The examiner shows the participant plates 1 & 2. He/she allows the participant to hold the plate card and trace the red line; thus allowing them to identify the shape as a circle or square. Once the individual has recognized the shape and understands the purpose of this screening, you may proceed to phase two. Phase two incorporates curved lines. For this part the individual will be asked to use a cotton tip applicator to trace the line. Show the individual plate 5 so they are able to see and understand what is being asked. Once the individual understands both portions, you may proceed with the actual screening.
Verbal Instructions:
Have the participant sit down. For plates 3 & 4 simply hold the color plate cards at least 20 inches away. (Must be held 20-30 inches away for accurate screening.). Ask the individual to name the shape on the card. After completion of plates 3 & 4 state that you will now be moving on to phase two of the examination. For this phase the individual will be tracing curved lines on plates 6-8. Hand the participant a cotton tipped applicator. Instruct them to use the cotton tipped applicator to trace the outline of the shape. For plates 6-8 the plate card must be at a distance of at least 25 inches away for accurate screening.
**Passing Criteria:
In order to pass the color screening the participant must correctly trace the curve/line from plate 8. In addition he/she must correctly complete/identify 3 from the following plates: 3, 4, 6, & 7. For the purpose of this screening inability to successful identify/trace plate 8 or missing 3 of the following plates: 3,4,6, &7 warrants a referral.