Vision Screening

Clarifying Color-Vision Deficiency Screening

by P. Kay Nottingham Chaplin, EdD

Good-Lite ColorCheck CompleteVision screeners frequently have questions regarding when to follow the recommended manufacturer instructions for color vision deficiency screening tools. This blog is designed to address that question, and also provides a solution for color vision deficiency screening in preschool- and school-aged children beginning at age 3 years.

Many state vision screening guidelines recommend that color vision deficiency screening follows manufacturer instructions when conducting the screening. Confusion may occur when the manufacturer instructions are written specifically for optometrists and ophthalmologists to use during eye examinations. Color vision deficiency testing in a doctor’s office differs from screening for color vision deficiencies in schools, Head Start programs, or similar settings.

Instructions for color vision deficiency testing may call for monocular testing - or testing one eye at a time with the other eye covered (occluded). When screening for color vision deficiencies in schools, Head Start, or similar programs, the screening should be conducted binocularly (both eyes open and uncovered).

This difference in monocular testing during an eye examination and binocular screening in school, Head Start, or similar settings is supported by James E. Bailey, OD, PhD, Distinguished Professor Emeritus, 2018, Southern California College of Optometry, Marshall B. Ketchum University, Fullerton, CA (personal communication, June 5, 2019).

If all vision screening for the child is successful except the color vision deficiency screening, the child should be referred to an eye doctor for an eye examination (Nottingham Chaplin, Baldonado, Cotter, Moore, & Bradford, 2018).

The eye care professional will confirm whether a color vision deficiency exists. If a child has a color vision deficiency, the eye care professional will also identify the type and severity (mild, moderate, or severe) … The eye care professional will also consult with the parents/caregivers regarding how the type and severity of the color vision deficit may affect the child’s learning, life, and career choices.

Ask the parents/caregivers to obtain a copy of the results from the eye care professional and to share those results with [school or Head Start staff, for example] because classroom and/or learning activities may require accommodations when color deficiencies are present.” (Nottingham Chaplin, et al., 2015, p. 211).

When state vision screening guidelines call for color vision deficiency screening for preschool- and/or school-aged screening, the Good-Lite ColorCheck Complete Vision Screener includes LEA SYMBOLS® for preschool-aged children and LEA NUMBERS® for school-aged children. The LEA SYMBOLS® section includes one demonstration plate and seven plates for red/green screening. The LEA NUMBERS® section includes one demonstration plate, 14 plates for red/green screening, and three plates for blue/yellow screening. Instructions are included in the Good-Lite ColorCheck Complete Vision Screener.

Screeners in a school, Head Start program, or similar setting using this book would conduct color vision deficiency screening binocularly (both eyes open and uncovered).



Nottingham Chaplin, P. K., Baldonado, K., Cotter, S., Moore, B., & Bradford, G. E. (2018). An eye on vision: Five questions about vision screening and eye health-Part 2. NASN School Nurse, 33 (4), 210-213.

Tips for Coordinating Spot Vision Screening Q & A

Spot Vision ScreenerWe received many questions during our Tips for Coordinating Spot Vision Screening webinar. As a resource for you, we have compiled the most frequently-asked questions and have provided them here with their answers.

If you have a question about the Spot Vision Screener and don't see an answer here, be sure to request a consultation with one of our vision screening experts!

Q: Do you still need to do a visual acuity test?
A: The Welch Allyn Spot Vision Screener uses a completely objective screening methodology to screen for 6 potential vision issues including amblyopic risk factors, common refractive errors, and strabismus. Visual Acuity testing is subjective but can identify visual problems unrelated to refractive error. Both screening methods have their benefits and limitations; therefore, the most thorough exam occurs when both instrument-based vision screening and visual acuity are used.

Q: Can I convert the results to a visual acuity score (20/20, 20/40)?
A: No. The Spot Vision Screener results will indicate “All Measurements in Range” or “Complete Eye Exam Recommended.” The device also lists the condition(s) found and the measurements of each eye. Welch Allyn does not recommend converting the results to a visual acuity score. If your state requires a visual acuity score we recommend using age appropriate tests and following state vision screening guidelines.

Q: How does it measure stereopticity?
A: It doesn’t. The Spot Vision screener is completely “objective” in that it requires no response. Whereas stereopsis is “subjective” (requiring a response from the subject).  That would be a different test. If your state requires a Stereopsis screening we recommend using age appropriate tests and following state vision screening guidelines.

Q: Does the result screen delineate between near and distance results?
A: Spot Vision Screener can detect measurements for Myopia (near-sighted) and Hyperopia (far-sighted) which are what a near or distance vision test looks for. In addition, Spot detects 3 amblyopic risk factors (Hyperopia, Strabisus (Gaze) and Anisometropia (unequal refractive power) as well as Astigmatism (blurred vision) and Anisocoria (unequal pupil size). 

Q: Can you screen children who are wearing glasses?
A: Yes, but it will take the glasses into consideration. Spot has criteria settings and if they are not referred then they met the criteria settings already established within the devices.

Q: Any suggestions on screening students who wear glasses?
A: Screening with glasses can be tricky, you can screen through single Rx Lens (no bifocals) with Spot. To screen students with glasses, push the glasses up the nose and drop the chin. This helps move the glare off the lens for a better capture. The thicker the lens, the more challenging it can be to screen through; this is also the case if the lenses have scratches on them. It is easiest to screen children wearing glasses in a dark room that minimizes reflections off the lenses.

Q: How accurate are the results? Sometimes if I screen the child two or three times I get both pass and refer.
A: It’s best to go with the first result while the eyes are in a natural relaxed state whereas continually screening the same patient can result in accommodation, thus skewing the results. 

Q: Why do I get different results for the same student if I have trouble screening and try again?
A: Accommodation is the ability for the human eye to improve vision when provided time to focus on an object.This is most widely discussed with amblyopic risk screening on children under age 6 but can still occur with subjects over 6 years of age. This also may occur when a child is just below or above the criteria threshold for their age, thus prompting multiple results. As with the previous question, the best practice is to go with the first result. 

Q: What is the recommended age for use?
A: Refer to the Welch Allyn statement regarding use of Spot Vision Screener in school-aged children.

Q: How reliable is this tool when screening children with developmental disabilities that have difficulty focusing on the machine?
A: Spot Vision Screener is an effective tool for screening children with developmental disabilities. Remember, Spot does not replace a comprehensive eye exam and children with disabilities may also need to see an eye doctor. Spot has an extremely high capture rate even with Autistic or developmentally delayed children. It’s vision optics system and design results in a high capture rate and the non-invasive screening distance of 3.3 feet helps allow the child to be comfortable without feeling like you’re invading their space. 

Q: How do you load student data for screening?
A: There are three options available for loading student data for screening into the device.  

  1. INSTANT SCREENING - Screen and then follow the prompts to enter the student’s information including name, ID, date of birth, gender, etc. 

  2. SELECT FROM THE QUEUE - Preload a list of students by utilizing the import/export function which allows you to create a spreadsheet and load the data into the device by using a USB.

  3. PRE-ENTER STUDENT DATA - Follow the prompts to enter the student’s information including name, ID, date of birth, gender, etc., then proceed to the screening portion.

Q: Is financial assistance available to purchase a Spot?
You might reach out to a local Lions Club or other local charitable organization, like Prevent Blindness, for assistance; they have helped with the purchase of equipment. Some schools have utilized their Medicaid reimbursement funds to purchase the Spot Vision Screener. Others have utilized the banner space at the bottom of the results page to raise funds by promoting local services and/or optometrists.

School Health Services Give Children a Bright Future

Shared with permission from the Healthy Schools Campaign.

Mary Ellen Barkman, the Medicaid Coordinator for Pinellas County Schools, the eighth largest school district in Florida, is passionate about their vision screening program. “We’re saving children’s lives,” she says.

Spot Vision ScreenerFor instance, last year, there was a new student in the district, a recent immigrant from Egypt who spoke only Arabic. Her teacher struggled to reach her and felt that beyond the language issue, the girl must have some cognitive problems. As part of her special education evaluation, she was tested with one of the district’s new Spot Vision Screeners. This quick screen showed that she had a serious muscle problem that caused triple vision. After she received the specialized prism glasses she needed and hearing aids for her hearing loss, she was at grade level within a year. “Without those screenings she may not have been able to reach her fullest potential,” Barkman says. “With help, children can have such a bright future.”

The district’s investment in spot screeners is the result of careful analysis of the district’s needs. Several years ago, school health services managers reported to Barkman that there was an issue with the district’s protocol for vision screenings. They were inefficient and time consuming, and they simply didn’t work for students who couldn’t talk or who had trouble sitting still or following instructions—often the very students who needed accurate screenings the most. The district researched many options and settled on Spot Vision Screeners, which work by taking a picture of the child’s eye and using it to screen for visual acuity, muscle imbalance and tumors. In fact, in the first year of using the screeners, the district identified a serious tumor in a student that had been missed by his primary care doctor. The machine creates a printout for parents that explains any follow-up services their child needs, and the district has formed partnerships with a vision van, local optometrists and the Lion’s Club to provide services for children who need follow-up services after screenings. And because the screeners are so easy to use, the district’s vision teams can make much more efficient use of their nurses to follow up with students who fail the screenings, rather than having to do the screenings themselves.

Barkman and the Pinellas County Schools team have woven together many different funding streams to build this unique program including Medicaid funding for the actual Spot Vision Screeners. Most of the funding comes from effective maximization of Medicaid billable services, such as Physical and Occupational Therapy, Speech Therapy, Nursing, Social Work, Psychology and Transportation and Administrative Claiming. Half of the reimbursement dollars are given to her program to spend on priorities they identify. The other half goes to operating to offset salary costs of billing providers. Because of this, Barkman works hard with her practitioners to make sure they are billing for all eligible services and maximizing Administrative Claiming reimbursement. They even developed their own electronic documentation system to make this easier. Over five years, the district has increased Medicaid revenue by $1.7 million to increase resources for students.

What’s next for Pinellas County? One priority is developing a micro-credentialing system for the one-on-one assistants who work with children with multiple challenges, to give them skills for physically transferring the children, feeding, seizure monitoring, CPR and social supports. Medicaid will support an increase in their salary after achieving the credential, which will allow them to be Medicaid-claimable health assistants. This invests Medicaid dollars directly into something that meets the needs of some of the district’s most vulnerable students.

“The key is out of the box thinking,” Barkman says, “and the box has gotten smaller.” She continues to look for ways to leverage whatever funding is available. “It’s such a blessing to be able to help a child reach their fullest potential. It’s important that people understand how important the Medicaid dollars are to that,” Barkman says.

Ask the Expert: Vision Screening with Dr. P. Kay Nottingham Chaplin, (EdD)

Ask The Expert

School Health is pleased to bring you this “Ask the Expert” blog with Dr. P. Kay Nottingham Chaplin, (EdD), director of Vision and Eye Health Initiatives for School Health and Good-Lite, member of the Advisory Committee to the National Center for Children’s Vision and Eye Health (NCCVEH) at Prevent Blindness, and co-chair of the NCCVEH Education/Data Subcommittee.

In this blog, Dr. Nottingham Chaplin will address a few commonly asked questions about vision screening, guidelines, and best practices.  


Q: What is the difference between optotype- and instrument-based vision screening?

A:  Optotype-based screening is the name for screening with tests of visual acuity, commonly known as eye charts. Software tests of visual acuity, such as EyeSpy 20/20™, are also available for optotype-based screening. “Optotype” is the name for pictures, letters, or numbers on tests of visual acuity.

Recognition visual acuity is the quantifiable, subjective measurement of the clarity, or clearness, of vision at the brain level when identifying black optotypes on a white background using specific sizes at a prescribed and standardized distance.

Instrument-based screeners neither measures visual acuity nor provide reports with visual acuity values (i.e., 20/XX). Instead, these devices analyze light reflecting from the retina at the back of the eye. This analysis provides information about the presence of risk factors in the eyes that may lead to decreased vision or amblyopia.

Instrument-based screening devices, such as the Welch Allyn® Spot™ Vision Screener, measure both eyes simultaneously and provide objective information about:

  • Significant refractive errors (i.e., hyperopia, myopia, and astigmatism);

  • Asymmetry of the refractive error from one eye to the other, known as anisometropia (for example, one eye may be myopic and the other hyperopic);

  • Misalignment of the eyes;

  • Presence of media opacities (i.e., cataract); and

  • Anisocoria (unequal pupil size).

Q: Do national guidelines or recommendations exist for instrument-based screening?

A: Two national guidelines or recommendations currently exist.

In 2015, the National Expert Panel (NEP) to the National Center for Children’s Vision and Eye Health at Prevent Blindness published recommendations for lay screeners, nurses, and others who screen children in educational, public health, or primary health care settings.

The NEP paper states that when screening children ages 3, 4, and 5 years, instrument-based screening is useful for shy, non-communicative, or preverbal children who cannot participate in optotype-based screening.

A guidance document from the American Academy of Pediatrics (AAP), American Association of Certified Orthoptists, American Association for Pediatric Ophthalmology and Strabismus, and the American Academy of Ophthalmology was published in 2016 for screening the vision of infants, children, and young adults. The AAP guidelines are for pediatricians and primary care physicians.

The AAP guidance document states:

  • Instrument-based screening can begin with children as young as age 12 months, although screeners will likely be more successful engaging a child at age 18 months.

  • At age 3 years, distance optotype-based screening may be attempted or the child can be screened with an instrument.

  • At ages 4 and 5 years, either distance optotype-based or instrument-based screening may be used.

  • At ages 6 years and older, optotype-based screening remains the preferred method, but instrument-based screening may be used when children and young adults cannot participate in optotype-based screening.

  • Instrument-based screening may be a helpful alternative when screening children of any age who have development delays.

Q: If I use an instrument, such as the Welch Allyn® Spot™ Vision Screener, do I need eye charts?

A: Screeners cannot successfully screen 100% of children with tests of visual acuity. Similarly, screeners cannot successfully screen all children with an instrument. Reasons may be related to pupil size, environmental lighting, and a child’s ability to fixate on the device’s target.

If you primarily conduct instrument-based screening, you want a test of visual acuity, such as an eye chart or Eye Spy 20/20, as a back-up jto be used if you cannot capture an reading with an instrument. For example, if an instrument has a 90 percent capture rate, a test of visual acuity will enable you to screen the other 10 percent of children the same day.

Whether you prefer optotype- or instrument-based screening, or a combination of the two approaches, a key to successful vision screening is using evidence-based tools and procedures as one of 12 components of a strong vision and eye health system of care. You can also use this checklist to evaluate your annual vision health program.

The right screening tools give us an important leg-up for identifying potential visual impairments. Screening with evidence-based tools helps ensure that we find and treat children with vision challenges so that all can learn and perform to the best of their abilities.
School Health offers a wide variety of optotype- and instrument-based screening tools to meet your needs. Click here to see our full line of vision screening products.

If you have a question that was not answered above, please let us know in the comment section below and we will research the answer.

Keep in touch with Dr. Kay!

For more information and references:
Vision and Eye Health at NASN:

Committee on Practice and Ambulatory Medicine, Section on Ophthalmology, American Association of Certified Orthoptists, American Association for Pediatric Ophthalmology and Strabismus, American Academy of Ophthalmology (2016). Visual system assessment in infants, children, and young adults by pediatricians. Pediatrics, 137(1), 1-3. Retrieved from

Cotter, S. A., Cyert, L. A., Miller, J. M., & Quinn, G. E. for the National Expert Panel to the National Center for Children’s Vision and Eye Health. (2015). Vision screening for children 36 to <72 months: Recommended Practices. Optometry and Vision Science, 92(1), 6-16. Retrieved from

Donahue, S. P., Baker, C. N., Committee on Practice and Ambulatory Medicine, Section on Ophthalmology, American Association of Certified Orthoptists, American Association for Pediatric Ophthalmology and Strabismus, American Academy of Ophthalmology (2016). Procedures for the evaluation of the visual system by pediatricians. Pediatrics, 137(1), 1-9. Retrieved from

National Center for Children’s Vision and Eye Health, Vision Systems, at

Nottingham Chaplin, P. K., Baldonado, K., Hutchinson, A., & Moore, B. (2015). Vision and eye health: Moving into the digital age with instrument-based vision screening. NASN School Nurse, 30(3), 154-60. Abstract available at

Nottingham Chaplin, P. K., & Bradford, G. E. (2011). A historical review of distance vision screening eye charts: What to toss, what to keep, and what to replace. NASN School Nurse, 26(4), 221-227. Abstract available at

Nottingham Chaplin, P. K., Marsh-Tootle, W, & Bradford, G. E. (2015). Navigating the path of children’s vision screening: Visual acuity, instruments, & occluders. Retrieved from

Year of Children’s Vision at

Much of the information for this document came from:

Nottingham Chaplin, P. K., Baldonado, K., Hutchinson, A., & Moore, B. (2015). Vision and eye health: Moving into the digital age with instrument-based vision screening. NASN School Nurse, 30(3), 154-60. Abstract available at



Are Your Eye Charts Up to Date? The Evolution of Eye Charts Over the Past 150 Years

StandardizeEyeChartsEye charts are an important part of vision screening, but how did these vision screening tools look in 1915? What about 1862? The answer may surprise you.


When you think of the word “Snellen,” you probably think of Snellen’s legacy – the Snellen Eye Chart with the big "E" at the top. This chart continues to hold a place of prominence on many walls in school nurse's offices and in the hallways of medical practices today.

Snellen, a Dutch ophthalmologist, introduced the first version of his eye chart in 1862, as a way to determine visual acuity (Bennett, 1965). Recently featured on CBS Sunday Morning, Snellen's work set a new standard for vision screening. His Snellen Eye Chart and the  Snellen Ratio are still in wide use today.

Before 1862, oculists used varied and sometimes interesting methods to assess visual acuity.

When the first school setting vision screening program began in 1899, a Snellen chart was used. (Appleboom, 1985) Many versions of eye charts have come and gone over the years, and even today's version of Snellen's chart differs from the 1862 version.

But did you know that the time-honored Snellen chart is not the preferred letter chart for testing visual acuity in 2015?

Why is a Snellen chart not the preferred chart of 2015?


While Snellen charts revolutionized vision screening programs they do not adhere to national and international guidelines for standardized eye chart design (Nottingham Chaplin & Bradford, 2011). Six guidelines for standardized eye chart design are (Nottingham Chaplin & Bradford, 2011):

  1. Optotypes should be of approximate equal legibility.

  2. Each line on an eye chart should have the same number of optotypes (typically 5).

  3. Horizontal spacing between optotypes should be equal to the width of the optotypes on a line.

  4. Vertical spacing between lines should be the height of the optotypes in the next line down.

  5. The size of optotypes should progress geometrically up or down the chart by 0.1 log units (i.e., 20/32 vs. 20/30).

  6. Optotypes should be black on a white background under good lighting conditions (luminance between 80 cd/m2 and 160 cd/m2).

If you were to draw a line around the outside of the ototypes on an eye chart adhering to the national and international guidelines, you would see a chart with an inverted triangle. Conversely, if you outlined the optotypes on a chart that does not adhere to national and international guidelines, you would see a chart with a rectangle.


So, look at the eye chart yesyou use. Do you see the inverted pyramid or a rectangle?

What should we use instead of Snellen charts for Vision Screening?


Despite many state, public health, & district vision screening guidelines listing Snellen as the preferred chart for school aged children it has been recommended to use Sloan charts for vision screening.

Developed by Louise Littig Sloan, phD, and Dr. Palmer Good, of The Good-Lite Company, the preferred tests of visual acuity for school-aged children and adults use Sloan Letters as optotypes.

Sloan published information about those letters in 1959 (Sloan, 1959). which was later used by vision professionals to design a new, standardized chart in the inverted pyramid format.

It is recommended to switch from Snellen to Sloan charts to ensure an evidence-based test of visual acuity for school-aged children that meets national and international design guidelines for standardized eye charts.

School Health offers a variety of Sloan charts and cards that meet the national and international guidelines. Call us today for a consultation on the Sloan-related screening products that are available to you.

Shop Sloan & Snellen Charts & Cards>>

Request a FREE Vision Screening Consultation>>


Appelboom, T. M. (1985). A history of vision screening. The Journal of School Health, 55(4), 138-141.

Bennett, A. G. (1965). Ophthalmic test types. A review of previous work and discussions on some controversial questions. The British Journal of Physiological Optics, 22(4), 238-271.

Nottingham Chaplin, P. K., & Bradford, G. E. (2011). A historical review of distance vision screening eye charts: What to toss, what to keep, and what to replace. NASN School Nurse, 26(4), 221-227.