Color Vision Testing Methods: Use in workplace screening

Scope

Purpose of this report was to evaluate color vision screening tests for performance and efficiency in detecting color vision deficiency (CVD) as part of the pre-placement examination.

Background

Medical centers according to The Joint Commission (JCAHO) do not have any specific requirements for color vision testing.¹ They do however recognize that human resources (HR) standards should already require an assessment of essential job functions and the ability of applicants to perform said functions.

Some jobs’ essential functions are partially governed by regulatory and credentialing bodies (FDA and CAP). However, they make no specific recommendations on testing modality or use of assistive devices.^2,3 For the screening of law enforcement officers and emergency medical services personnel, the American College of Occupational and Environmental Medicine provides a list of acceptable tests.⁴ Acceptable tests that are common in clinical practice include: Ishihara, Farnsworth D-15, and the HRR.

Considerations

When selecting a screening test, it is important to consider test performance (sensitivity, specificity), cost (time, equipment), ease of administration, detectable deficiencies (protan, deutan, tritan), and ability to measure the degree of impairment. The ability to measure degree of impairment is an important quality because individuals with mild CVD are likely able to adequately perform color vision sensitive tasks.⁴ Therefore, institutions may consider clearing applicants with normal color vision or mild CVD. Hiring managers may also consider follow on simulated job specific color task testing for applicants with CVD detected on screening.

Selecting a color vision test for pre-placement examinations begins with considering any pre-determined industry standards. JCHO, DOT, FDA, and CAP make no specific recommendations on testing method.^1-3,5 However, ACOEM in their guidance for LEO and EMS, concludes that the Farnsworth D-15, HRR, and Ishihara PIP are all reasonable, effective, and clinically readily available tests for CVD.⁴

Pseudoisochromatic Plates

Unlike the HRR and Farnsworth D-15, the Ishihara PIP is unable to detect tritan defects (weak blue function). However, because of its rarity (1 in 10,000), its value in screening is limited.⁴ The Ishihara is limited in its ability to measure degree of impairment (i.e., mild, moderate, severe). All three tests demonstrate a high level of agreement and effectiveness (sensitivity and specificity 95-99% and 91-99% respectively).^6,7

Pseudoisochromatic Plates

The HRR and Ishihara PIP utilize pseudoisochromatic plates. The plates contain colored dots that test an applicant’s ability to recognize colored figures against varying-colored backgrounds. The number of incorrect plates is scored to determine the presence of CVD or in the case of HRR, both the presence and severity of CVD. Pseudoisochromatic tests are rapid and easy to administer, taking only 1-2 minutes to administer.⁴ Average testing time for computer-based programs are relatively as rapid, average of 3.4 minutes.⁸

Hue Discrimination

The Farnsworth D-15 tests hue discrimination in screening for CVD.  Also, known as a color grading arrangement test, applicants are asked to order color-coded caps in an orderly progression of hue.⁹ Similar to the HRR, the Farnsworth D-15 can detect tritan defects (in addition to protan & deutan) and grade the severity of CVD. The examiner transcribes the cap order to a scoring template and traces the sequence evaluating for any “crosses” across the center of the circle template. Any cross through the center is consistent with a moderate to severe CVD. Administration time for the test is slightly longer (average 3 minutes) than for pseudoisochromatic plates.⁴

Computerized

Several small studies have validated and found moderate to high congruence between computerized color vision screening and their traditional physical mediums.^10-12 However, these studies also conclude the need for larger population-based tests to properly assess effectiveness in the detection of CVD. 

Recommendations

The HRR is clinically familiar, easy to use, rapid, effective, able to detect tritan defects, and grade CVD severity. It can be used alone to screen applicants for normal color vision and mild CVD vs those with mild-moderate CVD. As a standalone test it can quickly triage applicants according to need for further evaluation (ophthalmology evaluation and/or simulated work color task testing) or for clearance. Therefore, if not cost-prohibitive, the HRR should be considered as the color vision screening test of choice for pre-placement examinations.

Computerized based testing offers a free, readily available, and potentially effective method for CVD screening. However, further research is required to properly assess its validity prior to any large-scale implementation.

References:

1. The Joint Commission. Is employee color-blind testing required? https://www.jointcommission.org/standards/standard-faqs/laboratory/waived-testing-wt/000001719/. Published October 26, 2021.
2. FDA. Recommendations for clinical laboratory improvement amendments of 1988 . FDA. https://www.fda.gov/media/109582/download. Published February 26, 2020.
3. College of American Pathologists. GEN.55400 Visual Color Discrimination. In: Laboratory General Checklist: CAP Accreditation Program. Northfield, IL; 2021:87-87.
4. Leo guidance – by ACOEM. LEO Guidance – by ACOEM. https://www.leoguidance.org/. Published 2021.
5. Federal Motor Carrier Safety Administration. Subpart E – Physical qualifications and examinations (49 CFR 391.41(b)(10)). Part 391: Qualifications of Drivers and Longer Combination Vehicle (LCV) Driver Instructors.
6. Fanlo Zarazaga A, Gutiérrez Vásquez J, Pueyo Royo V. Review of the main colour vision clinical assessment tests. Arch Soc Esp Oftalmol (Engl Ed). 2019 Jan;94(1):25-32. English, Spanish. doi: 10.1016/j.oftal.2018.08.006. Epub 2018 Oct 22. PMID: 30361001.
7. Cole BL, Lian KY, Lakkis C. The new Richmond HRR pseudoisochromatic test for colour vision is better than the Ishihara test. Clin Exp Optom. 2006 Mar;89(2):73-80. doi: 10.1111/j.1444-0938.2006.00015.x. PMID: 16494609.
8. Murphy R. Comparing Color Vision Testing Using the Farnsworth-Munsell 100-Hue, Ishihara Compatible, and Digital TCV Software. CommonKnowledge. https://commons.pacificu.edu/work/sc/51864014-af13-4209-83d0-17cf35b33243. Published April 23, 2015. Accessed December 27, 2022.
9. Richmond Products. Richmond Products Optometry and ophthalmology – gulden ophthalmics. www.richmondproducts.com. https://www.guldenophthalmics.com/wp-content/uploads/2011/11/Richmond-Color-Tutorial-Final.pdf. Accessed December 27, 2022.
10. Seshadri J, Christensen J, Lakshminarayanan V, Bassi CJ. Evaluation of the new web-based “Colour Assessment and Diagnosis” test. Optom Vis Sci. 2005;82(10):882-885. doi:10.1097/01.opx.0000182211.48498.4e
11. Ng JS, Self E, Vanston JE, Nguyen AL, Crognale MA. Evaluation of the Waggoner Computerized Color Vision Test. Optom Vis Sci. 2015 Apr;92(4):480-6. doi: 10.1097/OPX.0000000000000551. PMID: 25785530.
12. Almustanyir A, Alduhayan R, Alhassan M, Bokhary K, Alabdulkader B. Evaluation of the Waggoner computerized D15 color vision test using an iPad device. J Opt Soc Am A Opt Image Sci Vis. 2021;38(11):1647-1655. doi:10.1364/JOSAA.431987