More than a mouthful

However, a heightened risk of developing certain eye conditions may not be foremost in a patient’s mind when they struggle to fasten their belt at the normal notch.

For optical professionals who are aware of this link, it can still be confusing to work out what advice to give patients on diet when the research is constantly evolving.

OT spoke with experts within optics for their take on the relationship between diet and eye health.

Vital vitamins

Head of the Centre for Eye Research Ireland at Technological University Dublin, Professor James Loughman, highlighted that diet is an important determinant of ocular health.

“A healthy diet is a key requirement for routine ocular function,” he said.

“Certain nutrients are essential for healthy vision and deficiency can lead to ocular dysfunction, disease and even blindness,” Professor Loughman highlighted.

He shared the example of vitamin A, which is found mostly in animal sources such as liver, eggs and dairy products.

We should be more proactive with all our patients as the modern diet is often far from ideal

Professor Loughman observed that vitamin A deficiency is common in many developing countries, typically in areas where it can be difficult to access nutrient rich foods.

The deficiency can lead to severe dry eye and corneal ulceration, while the effect on the retina can cause night blindness.

The antioxidant and anti-inflammatory properties of nutrients are also key to the long-term preservation of ocular health, Professor Loughman emphasised.

“Chronic inflammation and oxidative stress are the hallmarks of much age-related eye disease such as glaucoma and age-related macular degeneration,” he observed.

“It is not surprising, therefore, that a healthy diet rich in antioxidant vitamins and minerals provides the best natural means to prevent, delay or even treat ocular disease,” Professor Loughman added.

Pointing to vitamins with potent antioxidant properties, Professor Loughman highlighted vitamin C, E and zinc.

Dietary carotenoids, found in leafy green vegetables, coloured fruits and eggs, also boost eye health by enhancing the eye’s macular pigment layer.

Lack of awareness

Professor Loughman shared his belief that most people are not overly aware of the connection between nutrition and eye health.

“Awareness generally comes only when a person becomes symptomatic with increasingly prevalent lifestyle-related conditions such as dry eye,” he said.

To enhance awareness, Professor Loughman highlighted that both undergraduate and postgraduate optometry training needs to embrace the important role of nutrition.

“Optometrists then need to increase the emphasis on preventative health in primary care practice,” he added.

This would involve optometrists becoming better informed through exploring a patient’s diet in their case history or providing suitable questionnaires in waiting rooms.

Professor Loughman expressed his view that optometrists should not wait for symptoms of dry eye disease or another condition before responding with dietary guidance.

“We should be more proactive with all our patients as the modern diet is often far from ideal; high in processed foods that are rich in calories but poor in nutritional content,” he said.

When disease does occur, Professor Loughman emphasised that diet and suitable supplements should become a priority.

“For example, the simple prescription of eye drops for a patient with dry eye is easy but not likely to tackle the root cause of the condition,” he explained.

“A more comprehensive, lifestyle-based approach to patient management that includes dietary guidance will be infinitely more beneficial to the long-term health of every patient we see,” Professor Loughman elaborated.

Weighty issue

Dr James Brown, director of Aston University’s Research Centre for Healthy Ageing, highlighted that maintaining a healthy weight can reduce the risk of developing a number of eye conditions, including retinopathy and age-related macular degeneration.

“What we eat, including both the volume of food and particularly the make up of food, really can have an effect on your eye health,” he shared.

He emphasised that while many people are aware of the link between a poor diet, obesity, heart disease and type 2 diabetes, they were less conscious of the role that nutrition can play in supporting eye health.

Dr Brown highlighted that optometrists have a role to play in enhancing the public’s understanding of the link between nutrition and eye health.

“This can be done at consultations through structured conversations and through the use of infographics and posters in waiting rooms,” he shared.

“Additionally they can signpost clients to further information that can help support decision making around dietary habits,” Dr Brown added.

This could be supported by closer links between optometrists, dietitians and other primary care providers, he said.

Avoiding dry eye

Dispensing optician and nutrition specialist, Iain Johnson, highlighted that population studies illustrate that certain lifestyles and dietary behaviours offer protection against eye conditions, such as age-related macular degeneration.

“Finding the exact ingredients is the hard part,” he shared.

Mr Johnson explained that diets deficient in certain essential fatty acids have been shown to have a higher prevalence of dry eye disease.

He added that there is good evidence that increasing consumption of oily fish or taking a mixed essential fatty acid supplement can help those with the condition. 

Supplements are listed as one of the first treatment options in the Tear Film and Ocular Surface Society Dry Eye Workshop II, Mr Johnson highlighted.

Aside from dry eye, research has also illustrated the role of nutrition in cataracts and glaucoma.

It’s common sense that a good diet can help prevent heart disease – I doubt that most people would think the same for eye health

Mr Johnson shared that total antioxidant intake is inversely related with the risk of age-related cataracts, while the consumption of leafy green vegetables is shown to have a protective effect against glaucoma.

He agrees with Professor Loughman and Dr Brown that public awareness on the relationship between diet and eye health is limited.

“I think there’s a bit of a disconnect,” he shared.

“It’s common sense that a good diet can help prevent heart disease – I doubt that most people would think the same for eye health,” Mr Johnson elaborated.

Image credit: Getty/Aiselin82