Centre for Applied Vision Research at the School of Health and Psychological Sciences, City, University of London welcomes Marisa Rodriguez-Carmona to discuss their findings on recent advances in colour assessment with emphasis on the Colour Assessment and Diagnosis (CAD) test as part of the research seminar series.
Colour can enhance visual acuity and convey important information on the material properties of objects. Colour is also used to signal information and plays a major role in visual search. In addition, the colour attributes of images we see can enhance our perceptual experience. Not everyone has ‘normal’ colour vision.
The inability to identify or see colour signals correctly may have negative consequences in occupational environments. Equally important is the early detection of small changes in colour vision, which can signal the early onset of disease.
Conventional colour assessment tests do not always isolate colour signals, and frequently, the subjects can make use of other visual attributes and cues to pass as normal.
This presentation will describe recent advances in colour assessment with emphasis on the Colour Assessment and Diagnosis (CAD) test. The latter can be used to accurately classify an applicant’s class of colour vision and to quantify the severity of red/green (RG) and yellow/blue (YB) colour loss.
The establishment of reliable, normal-age limits has transformed the effectiveness of colour assessment as a clinical tool in the detection and monitoring of diseases.
Systemic diseases, such as diabetes and a range of other degenerative diseases of the photoreceptors, often manifest first through a reduction in YB and RG chromatic sensitivity.
‘Safe’ colour vision is often required as a condition for employment in many occupations, but the existing, conventional colour screening tests and protocols employed in many occupations often pass some applicants with severe colour deficiency and fail others who are less severe.
The statistical outcomes of the most commonly used colour vision tests will be described.
The results of the full CAD test in conjunction with detailed studies of minimum colour vision requirements in visually demanding occupations make it possible to establish scales for colour deficiency, but the full test can take between 12-15 minutes to complete and requires the use of fully calibrated equipment.
In order to enhance the efficiency of colour vision assessment, we have developed a new colour vision screener (CVS) test with close to 100% sensitivity and specificity.
The screener takes less than 3 minutes to complete and is administered first to every applicant to identify those with either congenital or acquired colour deficiency. Only ~ 6% of applicants (assuming equal numbers of males and females and ~2% acquired loss) require taking the full CAD test.
The use of the two-step protocol makes colour assessment more efficient by reducing significantly the number of applicants who require the full CAD test.
Equally important, recent advances in colour assessment, and also improved understanding of the factors that affect normal trichromacy and congenital and acquired colour deficiencies make the assessment of colour vision changes more reliable and the results fairer and more useful in both occupations and in the clinic.
About the speaker
Dr Marisa Rodriguez-Carmona studied Physics at Imperial College London before receiving her doctoral degree for work on “Variability in chromatic sensitivity" at the Centre for Applied Vision Research at City, University of London.
She is currently a senior lecturer in Optics and Visual Science at the SHPS (School of Health and Psychological Sciences).
She is Secretary and Board Member of the Colour Group of Great Britain. She received the Buckston Browne Award (from the Harveain Society) for her research in occupational medicine.
Her lines of research focus on the diagnosis of anomalies in colour vision, changes in visual performance in relation to aging and disease, and the optimisation of colour assessment protocols in the clinic and in occupations.