Professor John Barbur, Applied Vision Research Centre, The Henry Wellcome Laboratories for Vision Sciences, City University London, UK
Significant advances in our understanding of the genetics of colour vision make it possible to account for a great deal of the observed variability in both ‘normal’ trichromatic colour vision and in congenital colour deficiency [1, 2]. Recent developments in colour assessment techniques yield reduced within subject variability and hence more accurate assessment of both red / green (RG) and yellow / blue (YB) loss of chromatic sensitivity [3, 4] with reliable classification of the subject’s class of colour vision (i.e., normal trichromatic colour vision, deutan-, protan- or tritan-like and acquired deficiency). Colour assessment is now easier to carry out and the severity of colour deficiency can also be quantified more accurately with reliable separation of RG and YB loss leading to clear distinction between congenital and acquired loss. A third element that has contributed to the recent flurry of interest in colour vision is the availability of reliable data that describe the effect of normal aging on RG and YB chromatic sensitivity [5, 6]. Such advances have made colour vision assessment more attractive as a diagnostic tool for early detection of diseases of the retina such as age-related macular degeneration (AMD) and glaucoma and systemic diseases that can also affect visual function such as diabetes.
In this lecture I propose to review the outcome of conventional tests of colour vision and to present data obtained on the CAD test [3, 4] that describe the variability observed within normal trichromats and in subjects with congenital deficiency. This improved understanding has had significant effects on colour assessment and the establishment of minimum colour vision requirements within visually-demanding occupational environments. Studies that led to colour vision changes as a result of normal ageing and the application of these to early detection of acquired loss of chromatic sensitivity will be discussed. Finally, results of extensive, clinical studies designed to detect the earliest changes in colour vision in diabetes, glaucoma and AMD will also be presented.
1. Neitz, J. and Neitz, M. The genetics of normal and defective color vision. Vision Res, 2011. 51(7): p. 633-651.
2. Neitz, M. and Neitz, J. Molecular genetics of color vision and color vision defects. Arch. Ophthalmol. 2000. 118(5): p. 691-700.
3. Barbur, J.L., Birch, J. and Harlow, J.A.. Threshold and suprathreshold responses to chromatic stimuli using psychophysical and pupillometeric methods.1992. Optical Society of America.
4. Barbur, J.L. and Connolly, D.M. Effects of hypoxia on color vision with amphasis on the mesopic range. Expert Rev. Ophthalmol, 2011. 6(4): p. 409-420.
5. Paramei, G.V. and Oakley, B. Variation of color discrimination across the life span. J. Opt. Soc. Am. A Opt. Image Sci. Vis, 2014. 31(4): p. A375-A384.
6. Barbur, J.L. and Rodriguez-Carmona, M. Color vision changes in normal aging, in Handbook of Color Psychology, E. A.J., F. M.D., and F. A., Editors. 2015, Cambridge University Press: Cambridge, UK. p. 180-196.