Simulation of age-related lens yellowing in younger observers has little effect on FM 100 hue error score. A variety of other factors such as pupil size, background illumination level, iris colour and macular pigment density may contribute to the age-related increase in FM 100 hue scores.

Psychophysical measurements using achromatic grating resolution acuity in peripheral vision show a prominent retinal asymmetry in acuity which is consistent with predicted values based on available estimates of midget ganglion cell density. Recent studies have shown that peripheral grating resolution acuity values for short-wavelength-sensitive (SWS) isolating gratings in normal observers are closely related to predicted values based on the underlying small bistratified ganglion cell density. By measuring SWS resolution acuity at different locations across the visual field, we wished to see if any significant acuity asymmetry exists for the short-wavelength system. In addition to this, we wanted to compare SWS and achromatic resolution acuity at different retinal locations of equal eccentricity. SWS and achromatic grating resolution acuity was measured in two observers at a number of different retinal meridians of 10- and 25-deg eccentricity from the fovea, and out to 35-deg eccentricity along the horizontal meridian. Achromatic resolution acuity was higher than SWS resolution acuity at all locations. At 10-deg eccentricity there was slight radial asymmetry in SWS and achromatic acuity, both displaying highest acuity along the horizontal meridian. At 25-deg eccentricity, SWS and achromatic acuity showed significant asymmetry with acuity being higher in the nasal retina compared to the temporal retina and with higher acuity in the superior retina compared to the inferior retina. At 35-deg eccentricity, the acuity asymmetry along the horizontal meridian was maintained with acuity for both significantly higher in the nasal retina. The SWS acuity changes with eccentricity and meridian were qualitatively similar to that found for achromatic acuity at the majority of retinal locations. Like achromatic acuity, SWS acuity shows significant asymmetry at different retinal locations of equal eccentricity. This suggests that both the midget and small bistratified ganglion cell population density changes significantly with retinal location and eccentricity. SWS acuity appears to change in parallel with achromatic acuity for the majority of retinal locations measured, although the amount of nasotemporal asymmetry appears to be slightly less for the SWS system at 25- and 35-deg eccentricity.

The results indicate that there is no evidence of significant selective reduction in global SWS ganglion cell density in early to moderate glaucoma. However, there may be selective loss of SWS ganglion cell density at individual locations in individual eyes.

Background: It has been shown that rod-mediated dark adaptation is significantly delayed in ageing, a change which is exacerbated in age-related macular degeneration (AMD). Levels of lutein and zeaxanthin, the two main constituents of macular pigment have been found in rod outer segments, indicating that the macular pigment may have an influence on rodmediated dark adaptation. The aim of this study was to determine if rod-mediated dark adaptation is associated with central macular pigment levels in individuals with intermediate stage AMD. Methods: A cross-sectional observational study included individuals with acuity better than 6/15 Snellen and intermediate stage AMD based on graded fundus photographs using an internationally accepted grading scale. Rod-mediated dark adaptation was assessed at five degrees eccentricity in the superior retina (inferior visual field) using the rod intercept time measure from the MacuLogix AdaptDx. Macular pigment optical density was measured at 0.5 degrees eccentricity using a heterochromatic flicker photometry-based method. Results: Twenty-seven individuals (mean age 76.7 years) with intermediate stage AMD and 23 age-matched normal controls (mean age 74.0 years) were recruited. Rod-mediated dark adaptation was significantly delayed in intermediate stage AMD compared with healthy controls (32.9 minutes versus 10.7 minutes, p < 0.01). There was no statistically significant correlation between the rod intercept time and the level of macular pigment in those with intermediate AMD (r = −0.04, p = 0.85). Conclusion:The results did not support the hypothesis that higher macular pigment is associated with improved rod-mediated performance or that higher levels of macular pigment protect rod-mediated function in intermediate AMD.

Background: Individuals with higher than normal levels of macular pigment optical density (MPOD) are less affected by disability glare, when using glare source lights with a strong short-wavelength component. The aim of this study was to investigate whether estimates of retinal straylight from the Oculus Cataract Quantifier (C-Quant), which corresponds to disability glare, are associated with estimates of macular pigment levels in young Caucasian eyes. Methods: Thirty-seven Caucasian individuals (aged 19 to 40 years) with good visual acuity, free from ocular disease and with clear ocular media participated. Macular pigment optical density was measured at 0.5 degrees eccentricity from the foveal centre using a heterochromatic flicker photometry-based densitometer instrument from MacularMetrics. Retinal straylight was estimated using the C-Quant, a commercially available device, which uses a psychophysical compensation comparison method. Results: Mean MPOD was 0.39 ± 0.18 log units (range zero to 0.80) and was not significantly related to age (r = -0.07, p = 0.66). Mean straylight parameter (s) was 1.01 ± 0.09 log units (range 0.86 to 1.21) and was not significantly related to age (r = -0.03, p = 0.86). Although there was a small tendency for straylight measurements to be reduced in individuals with higher levels of MPOD, there was no statistically significant relationship between retinal straylight and MPOD (r = -0.17, p = 0.30). Conclusion: Ocular straylight, estimated by the Oculus C-Quant, is little influenced by macular pigment optical density. As the C-Quant uses balanced (white) lights, it is suggested that the previous findings on the effect of macular pigment critically depend on the use of blue-dominant glare sources.