For the past 50 years, clinicians have employed various colour vision assessments, including pseudoisochromatic plate (PIP) tests like the Ishihara and Hardy–Rand–Rittler (HRR) tests, the Farnsworth D15 (D15) test and the Heidelberg multi-colour oculus anomaloscope, to identify colour vision deficiency (CVD). In certain situations, these standard methods are supplemented with additional assessments such as the Farnsworth–Munsell 100 hue test, desaturated D15 versions and the Medmont C100.^1,2 PIP tests are used to screen for CVD, whereas D15 provides diagnostic information, such as identifying protan or deutan, and assessing severity.^1,2 Among these, the anomaloscope is not frequently used in clinical settings because it is expensive and time consuming. However, the anomaloscope is considered the gold standard for determining the type and severity of red–green defects.³

The healthcare industry is adopting several health tests and digitised products in an increasingly digitalised world. These tests can be performed using various digital devices, including personal computer screens, smartphones and tablets.^{4,5,6,7,8,9,10,11} Better healthcare outcomes can be achieved at lower costs using automated diagnostic methods and digitised tests. These digitised tests offer several advantages, including lower costs by eliminating the need for physical availability, time saving for clinicians, provision of a broad variety of colours, reduction of administrator biases, seamless integration with electronic medical records and prevention of colour plate ageing (for colour vision tests). Despite these benefits, digital testing of colour vision presents challenges, as different digital devices exhibit variations in display size, calibrations and screen analysis.^{4,5,6,7,8,9,10,11} Hence, creating a precise computerised colour vision test for commercial and public use is challenging, as the test must consistently display specific colours across various computers and types of display hardware.

Several computerised colour vision tests are available and can be applied to different digital devices. The Ishihara test is the most common colour vision screening test for red–green colour defects and provides information regarding the defect type (protan or deutan).¹ The Ishihara test is available in an electronic version and has been implemented using smartphones¹² and PC displays.¹³ Similarly, the Colour Vision Suit (Waggoner Diagnostics) is a colour vision test designed as a screener test to detect the presence of CVD. Furthermore, this test can also diagnose the type of defect, such as deutan, protan or tritan. The Waggoner computerised colour vision test (W-CCVT) screens for red–green and blue–yellow CVDs, classifies the type of red–green defect, and diagnoses the severity of the defect. The design of the test plates is similar to that used in the Ishihara test. Figure 1 illustrates the W-CCVT test. The W-CCVT test involves two main parts. Initially, a series of 25 stimuli is used to screen for red–green colour vision defects, with the screening phase concluding if the subject makes five errors. Upon completion or termination of this phase, the test moves on to the blue–yellow series. This is followed by a tritan screening and classification phase, which utilises 12 specialised plates. After completing the blue–yellow series, the test proceeds to a more detailed red–green diagnostic assessment. This comprehensive approach allows for a thorough evaluation of various aspects of colour vision, focusing on both red–green and blue–yellow colour perception abilities. If the individual fails the red–green screening plate test, the red–green diagnostic plates are administered. Half of the diagnostic plates display figure colours that are likely missed by individuals with protan vision, while the other half targets deutan vision. Individuals who fail to detect more saturated colours are classified as having more severe defects. Almustanyir and Hovis used a prototype of the W-CCVT on a desktop monitor and determined that the sensitivity and specificity of the test against the anomaloscope were 0.96 and 0.99, respectively.¹⁴

Digital colour vision tests are considered sufficient for the screening and diagnosis of individuals with dichromacy and anomalous trichromacy.^13,15 Rapid changes in relevant programmes and operating systems necessitate continued colour testing to confirm these findings. Consequently, this study aimed to evaluate the performance of W-CCVT on an iPad relative to the anomaloscope and Ishihara colour vision tests. This study can contribute directly to digitalising the clinical setting, and the W-CCVT on an iPad could serve as a potential substitute for conventional colour vision tests used in CVD screening.

Fifty-two participants with colour-normal vision (CNV) and 135 with red–green CVD were recruited from hospitals, schools, universities and public places in Riyadh, the capital city of Saudi Arabia. Colour vision deficiency was classified based on Rayleigh colour matching using the Heidelberg Multi-Colour (HMC) Oculus anomaloscope (Oculus Optikgeräte GmbH, Wetzlar, Germany). The right eye was examined using the anomaloscope. The research protocol adhered to the ethical guidelines outlined in the Declaration of Helsinki and received approval from the Office of Research Ethics at King Saud University’s College of Applied Medical Science (CAMS-046-3940).

The study demonstrated that the W-CCVT was a valid colour test in identifying red–green colour vision deficiencies, showing performance comparable to that of the printed tests evaluated in this study. The W-CCVT exhibited high sensitivity and specificity, which were not significantly different from those of the Ishihara and anomaloscope tests that were used as baseline. Although not statistically significant based on the 95% confidence intervals, the W-CCVT exhibited a lower level of agreement with the anomaloscope findings compared with the findings of previous studies.^14,15,18 Similar to the results reported in other studies,^14,15,18,19 all participants with dichromacy failed the screening plates (red–green) at either visit in this study.

In terms of the diagnosis series, the W-CCVT was relatively good at categorising participants as having either a deutan or protan deficiency (84% were correctly classified compared with that of the anomaloscope). Ng et al.¹⁵ showed that 89% of their sample (CVD = 59, CNV = 361) were correctly classified by W-CCVT. The minor difference between the current study and Ng et al.¹⁵ in terms of classification is likely attributed to the different screening plates used to display the test, as well as the variations in the number of patients with dichromacy between the studies.

The W-CCVT provides a qualitative assessment of defect severity, categorising it as mild, moderate or severe. The findings of this study align with those of Cole et al.², showing a good correlation between the severity ratings from the W-CCVT and the anomaloscope-matching ranges. Only two individuals with dichromacy were identified as having mild or moderate deficiencies by the W-CCVT. Consistent with previous research,^14,15 the W-CCVT sometimes classified participants with dichromacy as having moderate deficiencies.

The W-CCVT can screen for blue–yellow defects, and several participants with deutan deficiency failed these screening plates. Bailey et al.²⁰ also reported that patients with red–green CVD occasionally have an error on the HRR test blue–yellow plates. There are multiple reasons for blue–yellow failures in the W-CCVT. The increased number of errors on the blue–yellow plates could be related to short presentation times. The 2-s presentation time used by the W-CCVT could be short for participants with reduced sensitivity in the red–green zone. Furthermore, the 2-s presentation time resulted in errors on the printed blue–yellow screening plates compared with the red–green screening plates for participants in the CNV group.²¹ It is possible that the effect of shorter presentation times was more significant for participants with a red–green defect, even though the test colours were approximately orthogonal to the red–green axis of confusion. Another possible explanation for failing the blue–yellow screening series is that participants may not expect to see a figure or letter, which can lead to inattention and cause them to miss the figure.

The new W-CCVT in iPad devices can be used to detect red–green CVDs. In particular, the level of agreement between W-CCVT and the anomaloscope test was good in the dataset. Additionally, the W-CCVT can screen for blue–yellow defects. Individuals with deutan deficiency were prone to errors on these plates, particularly in W-CCVT. The blue–yellow failures were likely caused by multiple factors, including age, presentation times, expectation errors and incorrect responses.

The adoption of computerised colour vision tests offers several significant advantages over traditional manual methods that rely on physical colour plates or slides. Unlike conventional tests, which are susceptible to fading over time, damage from fingerprints and variability because of inconsistent lighting conditions, computerised tests maintain consistent colour presentation and are not subject to physical degradation.^15,22 Furthermore, computerised platforms allow for precise control of background illumination, ensuring standardised testing environments and minimising external influences on test results.^15,22 These digital tests can also be easily updated through software enhancements and transferred across devices, such as replacement iPads or computers, thereby extending their usability and relevance without the need for physical replacement of materials.²³ Additionally, computerised systems facilitate automated scoring, integration with electronic health records and efficient data management, further streamlining clinical workflows and improving reliability.²³ Collectively, these features not only enhance the accuracy and reproducibility of colour vision assessments but also reduce long-term costs and logistical challenges associated with manual testing methods.

While the W-CCVT is a recent advancement, there is a lack of published studies evaluating its validity and reliability. Comprehensive validation and independent assessments are still needed. This study provided initial evidence regarding the W-CCVT’s clinical utility, but further research is required to confirm these findings. Furthermore, the W-CCVT showed limitations in classifying defects as either protan or deutan deficient. However, the accuracy of the diagnostic plates was higher than that of the Ishihara test. Furthermore, the W-CCVT can qualitatively diagnose the severity of the defect; however, its agreement with the anomaloscope was not adequate. Some participants with dichromacy were classified as having mild or moderate deficiencies, whereas those with mild defects were classified as moderate or severe. This indicates that this test must not be relied upon solely to assess the severity of defects. For precise assessment, particularly when the severity of the defect is crucial for occupational purposes, the D15 or anomaloscope tests are recommended. Another limitation of this study was the relatively small number of participants who returned for the second testing session. This limited follow-up sample reduces the statistical power and may affect the robustness of the test-retest reliability analysis. Future studies with larger and more representative follow-up cohorts are needed to confirm and extend the repeatability assessment of the W-CCVT. Although the W-CCVT includes 12 plates specifically designed to detect tritan defects, no participants with tritanopia were identified in this study. This condition is a very rare condition, which likely explains its absence in our sample. Consequently, the test’s ability to detect tritan colour vision deficiencies could not be evaluated.

The W-CCVT demonstrates satisfactory performance as a colour vision screening tool, offering significant benefits and providing reasonable accuracy in the identification of CVD. Incorporating this test along with other established colour vision evaluations could enhance the overall diagnostic toolkit available to practitioners. Furthermore, the W-CCVT tended to classify participants with more severe symptoms than the anomaloscope, a trend consistent with other PIP assessment tests.