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Imperfect optics may be the eye's defence against chromatic blur


The optics of the eye cause different wavelengths of light to be differentially focused at the retina. This phenomenon is due to longitudinal chromatic aberration, a wavelength-dependent change in refractive power1. Retinal image quality may consequently vary for the different classes of cone photoreceptors, cells tuned to absorb bands of different wavelengths. For instance, it has been assumed that when the eye is focused for mid-spectral wavelengths near the peak sensitivities of long- (L) and middle- (M) wavelength-sensitive cones, short-wavelength (bluish) light is so blurred that it cannot contribute to and may even impair spatial vision2,3. These optical effects have been proposed to explain the function of the macular pigment4, which selectively absorbs short-wavelength light, and the sparsity of short-wavelength-sensitive (S) cones5. However, such explanations have ignored the effect of monochromatic wave aberrations present in real eyes. Here we show that, when these effects are taken into account, short wavelengths are not as blurred as previously thought, that the potential image quality for S cones is comparable to that for L and M cones, and that macular pigment has no significant function in improving the retinal image.

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Figure 1: MTFs at 550 nm (solid curves) and 450 nm (dotted curves) for two eyes: (1) a theoretical model eye subject to LCA but with no wave aberrations (thin lines) and (2) a real human subject's eye (thick lines).
Figure 2: MTF area.
Figure 3: Polychromatic MTFs computed with a 6-mm pupil for L cones (dashed line), M cones (solid line) and S cones (dotted line) for theoretical model eye with LCA only (a) and three subjects (b, observer 1; c, observer 2; d, observer 3) with measured LCA, TCA and wave aberrations.
Figure 4: Polychromatic MTFs for the theoretical model eye (thin lines) and for one subject (thick lines) with (solid lines) and without (dotted lines) the effect of macular pigment absorption at short wavelengths.

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  1. Bedford, R. E. & Wyszecki, G. W. Axial chromatic aberration of the human eye. J. Opt. Soc. Am. 47, 564–565 (1957).

    Article  CAS  PubMed  Google Scholar 

  2. Boynton, R. M. Human Color Vision (Holt, Rinehart & Winston, New York, 1979).

    Google Scholar 

  3. Mollon, J. D. A taxonomy of tritanopias. Docum. Ophthalmol. Proc. Ser. 33, 87–101 (1982).

    Google Scholar 

  4. Reading, V. M. & Weale, R. A. Macular pigment and chromatic aberration. J. Opt. Soc. Am. 64, 231–234 (1974).

    Article  ADS  CAS  PubMed  Google Scholar 

  5. Mollon, J. D. “Tho’ she kneel’d in that place where they grew..”. The uses and origins of primate colour vision. J. Exp. Biol. 146, 21–38 (1989).

    CAS  PubMed  Google Scholar 

  6. Marcos, S., Burns, S. A., Prieto, P. M., Navarro, R. & Baraibar, B. Investigating sources of variability of monochromatic and transverse chromatic aberrations across eyes. Vis. Res. 41, 3862–3871 (2001).

    Article  Google Scholar 

  7. Thibos, L. N., Ye, M., Zhang, X. & Bradley, A. Spherical aberration of the reduced schematic eye with elliptical refracting surface. Optom. Vis. Sci. 74, 548–556 (1997).

    Article  CAS  PubMed  Google Scholar 

  8. Rynders, M., Lidkea, B., Chisholm, W. & Thibos, L. N. Statistical distribution of foveal transverse chromatic aberration, pupil centration, and angle psi in a population of young adult eyes. J. Opt. Soc. Am. A 12, 2348–2357 (1995).

    Article  ADS  CAS  Google Scholar 

  9. McLellan, J. S., Marcos, S. & Burns, S. A. Age-related changes in monochromatic wave aberrations of the human eye. Invest. Ophthalmol. Vis. Sci. 42, 1390–1395 (2001).

    CAS  PubMed  Google Scholar 

  10. Stockman, A., MacLeod, D. I. A. & Johnson, N. E. Spectral sensitivities of the human cones. J. Opt. Soc. Am. A 10, 2491–2521 (1993).

    Article  ADS  CAS  Google Scholar 

  11. Porter, J., Guirao, A., Cox, I. G. & Williams, D. R. Monochromatic aberrations of the human eye in a large population. J. Opt. Soc. Am. A Opt. Image Sci. Vis. 18, 1793–1803 (2001).

    Article  ADS  CAS  PubMed  Google Scholar 

  12. Wysecki, G. & Stiles, W. S. Color Science: Concepts and Methods, Quantitative Data and Formulae (Wiley, New York, 1982).

    Google Scholar 

  13. Haegerstrom-Portnoy, G. Short-wavelength-sensitive-cone sensitivity loss with aging: a protective role for macular pigment? J. Opt. Soc. Am. A 5, 2140–2144 (1988).

    Article  ADS  CAS  PubMed  Google Scholar 

  14. Snodderly, D. M. Evidence for protection against age-related macular degeneration by carotenoids and antioxidant vitamins. Am. J. Clin. Nutr. 62 (6 Suppl.), 1448S–1461S (1995).

    Article  Google Scholar 

  15. Landrum, J. T. & Bone, R. A. Lutein, zeaxanthin, and the macular pigment. Arch. Biochem. Biophys. 385, 28–40 (2001).

    Article  CAS  PubMed  Google Scholar 

  16. Marcos, S., Burns, S. A., Moreno-Barriuso, E. & Navarro, R. A new approach to the study of ocular chromatic aberrations. Vis. Res. 39, 4309–4323 (1999).

    Article  CAS  PubMed  Google Scholar 

  17. Winn, B., Whitaker, D., Elliot, D. B. & Phillips, N. J. Factors affecting light-adapted pupil size in normal human subjects. Invest. Ophthalmol. Vis. Sci. 35, 1132–1137 (1994).

    CAS  PubMed  Google Scholar 

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The authors thank D. Williams for comments on the manuscript.

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Correspondence to James S. McLellan.

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McLellan, J., Marcos, S., Prieto, P. et al. Imperfect optics may be the eye's defence against chromatic blur. Nature 417, 174–176 (2002).

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