Better nutrition for better eyesight
Parents have long tried to persuade children to eat their greens by promising it will give them better eyesight. We all know that our vision deteriorates as we get older. Dr John Nolan is using his Starting Grant from the ERC to develop a targeted approach that could optimise the nutrition of the eye. This research will lead to improvements in eyesight for many sufferers of impaired vision, and potentially be beneficial even for those who are considered to have ‘normal’ vision.
© Shane O'Neill, Aspect Photography
Age-related macular degeneration (AMD) causes more than half of the cases of blindness in the developed world. This condition does not only have physical consequences – it has profound social and psychological consequences for sufferers, such as loneliness and depression. Around 15 million Europeans have AMD today, and this number is projected to double over the next decade as Europe’s population ages.
The problem largely stems from deterioration in the central part of the retina, called the macula. As we age, our eyes’ cells accumulate damage from the effects of oxidising chemicals, such as free radicals, and from blue light. There is now growing evidence that a lack of macular pigment (MP) in this part of the eye is associated with more retinal damage from these sources, and a correspondingly increased risk of AMD.
“The question we are asking is how to optimise this pigment at the back of the eye,” explained Dr Nolan, Principal Investigator at the Waterford Institute of Technology’s Macular Pigment Research Group in Ireland. “Our approach is to optimise nutrition for the eyes, which we hope will protect the retina through the ageing process – and even produce improved ‘super-vision’ for those with normal eyesight.”
Sunscreen for the eye
Chemicals called carotenoids are key, 60 of which are found in the typical Western diet. Only three of them, however, occur in MP in the retina – lutein (L), zeaxanthin (Z) and meso-zeaxanthin (meso-Z) – and the concentrations of these pigments vary from individual to individual.
As well as contributing to retinal damage, blue light is also the part of the spectrum most subject to scattering – which causes glare. To combat this, the yellow pigments, which absorb blue light, act “like sunscreen for the eye,” according to Dr Nolan.
“Our study will enrich MP through diet and supplements, and then measure the impact on improving vision. These pigments are also antioxidants – so increasing them could potentially have a double protective effect.”
Part of the challenge is to measure any improvements in eyesight: “We know the way vision is measured today is limited.” ERC funding has already helped Dr Nolan to assemble a specialist team and the advanced equipment needed for new tests. “These will go beyond familiar opticians’ tests designed to assess the need for corrective lenses.” Dr Nolan explained that the standard tests use white backgrounds and black letters, which are not sensitive enough to measure improvements in young people's eyesight and for those with normal vision “but we will look into effects from colour and contrasts.”
There could be significant economic benefits: not only from a reduction in the incidence of impaired vision in older people, but also from improvements for all those who depend on good eyesight for their work, and better testing techniques for other vision problems. ERC support has also attracted the funds needed for a new Vision Research Centre at the Waterford Institute of Technology, which was recently opened by Ireland’s Prime Minister, Mr Enda Kenny.
Dr Nolan expects to have established the initial baseline comparisons by the end of summer 2012, with the project’s first publications following soon afterwards. Full results should start to become available in around three years’ time.
For further information
Website of Dr John Nolan’s Macular Pigment Research Group
Age-related macular degeneration (AMD) – a loss of vision in the centre of the visual field, due to damage to the retina, which usually affects older people.
Antioxidant – a molecule able to inhibit oxidation of other molecules. Oxidation can be damaging to living things and oxidative stress appears to be a contributing factor in many human diseases.
Carotenoids – there are over 600 known carotenoids, organic pigments that occur naturally in plants to protect them from photo-damage and absorb light for photosynthesis. Many of them are antioxidants.
Free radicals – atoms, molecules, or ions featuring unpaired electrons, giving them an important role in many chemical processes in living organisms.
Macula – a yellow-pigmented oval-shaped area, approx. 5mm across, near the centre of the human retina. Damage to the macula leads to macular degeneration, impaired vision and blindness.
Macular pigment – due to its yellow colour, it absorbs excess blue and ultraviolet light, protecting the central part of the retina, which is responsible for high-resolution vision.
Retina – the light-sensitive tissue lining the inner surface of the eye which enables us to see. Light striking cells in the retina initiate nerve impulses to the visual centres of the brain.