Macular Pigment and its Correlation with Colour Vision and SWAP Perimetry
Document Type Conference Paper
European Vision and Eye Research conference 2008 Acta Ophthalmologica
Purpose To investigate the effects of macular pigment optical density (MPOD) on colour vision and colour modulated visual fields using short-wavelength automated perimetry (SWAP). Methods Macular pigment (MP) spatial profile was measured using customised heterochromatic flicker photometry (cHFP) on 51 normal subjects. Colour vision was assessed using the Oculus anomaloscope [Moreland equation (AME)] and Farnsworth-Munsell 100-Hue (FM) with optimum confusion axes. A custom designed program on the Humphrey automated perimeter, was used to determine SWAP thresholds at the fovea, and at each degree of retinal eccentricity for the central five degrees. A 440nm Goldmann V stimulus presented on a 100cd/m2 bleaching background was used to isolate the short wave sensitive pathway. Results While inter-relationships were evident between AME, FM and SWAP, only one colour vision measure (on FM) correlated with MPOD (r=.302, p= 0.03). At similar degrees of eccentricity, SWAP was inversely and statistically significantly correlated with MPOD (e.g. 1-degree retinal eccentricity: r = -0.198, p = 0.047; 3 degrees retinal eccentricity r = -0.290, p = 0.03). Conclusion Colour vision, even using sensitive tests targeting blue-yellow and blue-green confusion is surprisingly independent of MPOD, while SWAP sensitivity is reduced with increased MPOD. We hypothesize that this is due to long-term adaptation of the retinal blue-yellow pathway to prevailing MPOD in normal subjects, this adaptation being upset by short-term chromatic adaptation in SWAP.