19 April 2017
18 November 2011
According to a new US study, supplementation with zeaxanthin can improve visual acuity in elderly patients with age-related macular degeneration independently of lutein.
In the randomized controlled trial, 60 predominantly male patients (aged 74.9 years on average) with mild-to-moderate age-related macular degeneration (AMD) were randomly assigned to receive 8 mg zeaxanthin,
8 mg zeaxanthin plus 9 mg lutein or 9mg lutein for one year (1). The participants’ low- and high-contrast visual acuity, glare recovery, and contrast sensitivity function were measured at 4, 8, and 12 months. The study results showed that the participants receiving zeaxanthin had improved recognition of fine detail –an average improvement of 1.5 lines or 8.5 letters on an eye chart – and the disappearance of blind spots. The lutein group was superior in terms of low-contrast visual acuity, contrast-sensitivity function, and glare recovery.
The researchers concluded that zeaxanthin has unique lutein-independent visual-enhancing properties, such as improved high-contrast visual acuity, consistent with its position in the foveal system. In contrast to this, lutein, owing to its greater parafoveal retinal distribution, proved superior in improving contrast sensitivity, and glare recovery. There would be little doubt that raising macular pigment via zeaxanthin supplementation alone results in curative visual benefits to AMD patients with lesser disease, through enhancement of visual function.
Foveal, parafoveal, and peripheral vision work together to produce overall visual perception, but each has distinct characteristics that are significant when discussing vision and lighting. The fovea is the central area of the retina, also called the macula. This central area is filled with cone photoreceptors, however the fovea contains fewer short (blue) cones and no rods at all. Parafoveal describes the region surrounding the fovea. This region of the retina has a mix of photoreceptors, with all three types of cones and rods present. Peripheral refers to the region of the retina outside the central area. The periphery of the retina has a low density of cones of all three types, but is dominated by rods.
19 April 2017
25 April 2012
Supplementation with vitamin C may moderately reduce blood pressure, with even greater benefits for people with hypertension, says a new data analysis from the US.
24 November 2009
Almost half of UK women could be suffering from a lack of vitamin A because of a previously undiscovered genetic variation, scientists at Newcastle University have found.