Abstract
Purpose :
Macular pigment is a blue-light absorbing pigment in the center of the retina. It consists of carotenoids (lutein, zeaxanthin, meso-zeaxanthin) which can be modified by diet and is thought to be protective against the development of eye diseases such as age-related macular degeneration. Since denser macular pigment allows less blue light to reach the retina, we wish to determine whether normal variation in macular pigment optical density (MPOD) impacts color vision for detection of blue targets in a normal, healthy population. Our primary outcome was performance on the Cone Contrast Test (CCT). The null hypothesis was that normal variation in MPOD will have no significant impact on blue-cone color vision. The alternative hypothesis was that denser MPOD will lead to lower performance on blue-cone color vision.
Methods :
Eighty eyes of forty adult subjects were included in this study (mean age 27 +/- 8 SD, 21-53 years old, 28 females, 12 males). High contrast visual acuity and small letter contrast sensitivity were measured with the retro-illuminated Super Vision Test (Precision Vision). Color vision was screened using the Ishihara and HRR pseudoisochromatic plates. Color vision performance was measured using the CCT (Innova Systems). MPOD was measured from right and left eyes using heterochromatic flicker photometry (QuantifEye MPS II).
Results :
There was no significant difference between the right and left eye’s MPOD values therefore we used the mean MPOD for statistical analysis. A series of regression analyses did not reveal any systematic relationship between MPOD and CCT, however there was a significant difference in S-cone CCT scores for subjects with MPOD values above the median (0.50) versus those below. The mean S-cone CCT score for higher MPOD values (92) was lower than the mean for lower MPOD values (97; mean difference = 5, 95% CI: 1- 8, p<.017). In contrast, there were no differences for M-cone or L-cone CCT scores (p>0.56).
Conclusions :
Our study reveals a significant difference in CCT-measured chromatic discrimination thresholds between subjects with MPOD values above and below 0.50. This suggests that a five-point correction factor for blue-cone CCT scores could be utilized for those with higher MPODs in the presence of acquired pathology, which contributes to our understanding of acquired color vision deficiency and MPOD's relevance in chromatic discrimination assessment.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.