Abstract
Purpose::
Age-related macular degeneration (AMD) is the most common cause of age-related blindness in the western world. The exact cause of AMD is unclear; however, damage caused by short wavelength light and oxygen is believed to be important. Macular pigment (MP), composed of dietary zeaxanthin (Z), dietary lutein (L) and its stereoisomer meso-zeaxanthin (MZ), absorbs damaging blue light and protects against oxidative damage. Therefore, MP is believed to be important in protecting against AMD. This study was designed to investigate MP and serum concentrations of its constituent carotenoids in an elderly population.
Methods::
30 subjects were recruited into this study. Serum concentrations of L and Z were quantified using HPLC. MP optical density was measured using a MacuscopeTM employing the principal of heterochromatic flicker photometry (HFP). In addition, vision and lifestyle details were recorded by questionnaire and serum cholesterol levels and body mass index were measured for each subject.
Results::
The mean (± SD) age of our study group was 63 (± 10) years. Mean (± SD) MP optical density (at 0.5o eccentricity) was 0.261 (± 0.174). Mean (± SD) serum L and Z concentrations were 0.088 (± 0.026) and 0.011 (± 0.006), respectively. There was a weak positive relationship between serum concentrations of L (and Z) and MP optical density (r = 0.3 and r = 0.137. respectively). Serum cholesterol was inversely related to MP optical density (r = -0.575, p > 0.05). Also, subjects with high serum cholesterol levels (≥ 5 mmol/L) had significantly lower MP optical density than subjects with low serum cholesterol levels (< 5 mmol/L) [mean (± SD) MP optical density was 0.146 (± 0.069) and 0.376 (± 0.175), for high and low serum cholesterol groups, respectively].
Conclusions::
Subjects with high serum cholesterol levels display a significant lack of MP. The importance of this finding rests on the fact that cardiovascular disease represents a risk factor for AMD. Further study is required to assess the implications of our finding.
Keywords: macular pigment • carotenoids/carotenoid binding proteins • age-related macular degeneration