FOOD FOR THOUGHT

EYE PROTECTION
Back in July GI News we focused on our eyes because protecting our eyesight is one of the most important things we can do for the quality and enjoyment of life. Evidence to date says the ayes have it for a good diet with plenty of veg (good carbs and leafy greens) rich in lutein and zeaxanthin.” We recently came across some kids’ lutein and zeaxanthin supplements that claim to “guard” or “shield” their young eyes from harmful blue light. We asked ophthalmologist Dr Shanel Sharma to tell us about blue light, whether such a supplement could guard kids’ eyes from it, and what tips she has for parents to protect their kids’ eyes to ensure their enjoyment of life.

Blue light refers to the light at the blue end of the visible spectrum. Most of the blue light that enters our eyes comes from the sun and the blue light we absorb from digital devices is very low in comparison to that. That said, it is worth noting that there is no evidence to date to suggest that blue light is harmful to human eyes. Despite this, parents are often made to feel guilty that their child is exposed to blue light from the digital devices that have now become a part of everyday life.

What about the blue light science? Retinal surgeon Dr Daniel Polya reports: “There is some evidence that taking a plate of rodent retinal cells in a lab and exposing them to high intensity blue light can cause damage to those cells. However, the doses of light in this study are not reflective of real life situations, and thus the clinical relevance of these studies has to be questioned.”

What this shows is that while it is possible to create artificially a situation in which high intensity blue light can cause damage to exposed retina cells, this doesn’t reflect the real world. For example, the intensity of the blue light used in these experiments is much higher than we would be exposed to in real life, regardless of how long a person is exposed to digital devices. Therefore, using this type of experiment to “prove” the need for blue light protection is misleading.

In terms of taking supplements such as lutein and zeaxanthin to protect our eyes, the truth is that our bodies are very well equipped to absorb these from our food, and in fact over supplementing might have a negative effect. Associate Prof Wilson Heriot from Melbourne University says: “Eating a healthy diet, which includes green leafy vegetables, tomatoes, carrots, capsicum and oranges is all we need for a natural source of these vitamins. Our body is extremely efficient at absorbing lutein and zeaxanthin from the gut. Flooding the gut with alternatives such as carrots or beta-carotene supplements decrease the efficiency of lutein and zeaxanthin uptake.”

As an ophthalmologist, I have particular concern regarding supplements that include beta-carotene in the formula as scientific evidence demonstrates that beta-carotene is associated with an increased incidence of lung cancer in smokers. I would be concerned about children being given beta-carotene, particularly those exposed to second hand smoke. In particular, I would not recommend taking vitamins for which there is no evidence from randomised controlled trials, as the possible toxicities of any particular combination of supplements in children is unknown at this stage.

Parents should feel comfortable allowing their children to spend some time on devices, particularly as so much homework is now on computers. However, it is important that the use of devices is limited, and children are encouraged to play outside.

While blue light has not been shown to damage eyes, it has been shown to affect sleep patterns. Also, time spent playing outside can help children in keeping fit and absorbing important vitamins from the sun. I would stress that it is much more important to protect children’s eyes from UV sunlight damage than to be concerned about the low intensity blue light from digital devices because there is a lot of evidence that UV sunlight damages the eye and surrounding structures. “Studies show that UV damage to eyes occurs in childhood and is linked to eye disease later in life, including cataracts, pterygium, solar keratopathy, and skin cancer of the eyelids and around the eyes” says Dr Alina Zeldovich, eye surgeon and clinical lecturer at Sydney University.

Ophthalmologists have seen a sharp increase in the number of children presenting with eye damage caused by UV exposure (most of that damage occurs before 18 years of age). This is not surprising because UV levels have increased dramatically over recent decades. “The level of eye protection needed now is much greater than it was in the past, and so parents and schools need to be even more vigilant in ensuring that children’s eyes are protected. Children should wear suitable hats and sunglasses whenever they are outdoors” says Zeldovich.

How can you protect your children’s eyes? Ophthalmologists recommend you ensure they wear broad brimmed hats, sunblock and sunglasses that are rated Category 3 of the Australian Standards for UV protection when outdoors.

The sunglasses should have:

• A wraparound frame, designed to minimise unfiltered side light entering the eye 
• Polarised lenses with UV 400 protection, and 
• Lens coatings to block reflected light from entering the eye.