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C-54859

Dry eye – the role of nutritionals

This article considers the role of nutritional supplements as part of the management approach for patients with dry eye disease.

Introduction 

Dry eye disease is a common complaint that affects a large proportion of the UK population. It is difficult to establish the exact prevalence of dry eye because there is no single classification of the disease and it is multifactorial with many possible causes. One of the biggest risk factors is age, with studies suggesting that anywhere between 5–30% of patients aged 50 and above suffer from dry and uncomfortable eyes.

Artificial tears seem to be the first treatment option and there is no shortage of brand choice and formulation, each advertised to treat a specific subset of the condition. Heated eye masks are now common along with a large variety of lid hygiene products. Although we seem to be making large strides in all of these areas, there is one significant omission – nutritionals. And this isn’t just from anecdotal evidence – the NHS website doesn’t acknowledge nutrition as a possible management intervention for dry eye,2 and neither does the College of Optometrists.

Dry eye risk factors 

Computers and tablets play a central role in most modern work environments and the increase in their use may be fuelling the rates of dry eye. Studies have shown that when someone uses a VDU their blink rate drops from an average 22 blinks per minute to a rate of just seven.4 This decreased blink rate leads to more tear evaporation and as a consequence, dry eye symptoms may result. The reason why people blink less when using a VDU is thought to be linked to visual concentration,5 so this reduced blink rate is not only associated with the computers at work, but also hand held devices that we use far more frequently, such as smartphones. According to OFCOM, the average person uses a smartphone for two hours per day, and this is likely to be in addition to their VDU use at work. 

Contact lenses are another consideration with dry eye being a significant reason for patients to discontinue wear.6 Contact lenses themselves may actually increase the prevalence of dry eye, with these patients 12 times more likely to suffer than emmetropes.7 

Myopia rates are increasing rapidly, with the incidence doubling in the last 50 years.8 Some of the most successful treatment options for myopia control rely on contact lens interventions such as orthokeratology and multifocal soft contact lenses. Using all the available tools we have to manage dry eye could be increasingly important in this area.

Figure 1

The role of supplements 

The link between nutrition and dry eye disease has been the focus of research for over 20 years with the majority of the literature showing that omega-3 is an effective treatment option. Omega-3 is a polyunsaturated fat and along with omega-6 is one of the essential fats that we need in our diet for optimal health. Omega-6 is present in a large variety of foods, and it is unlikely that anyone would be deficient. However, omega-3 is less easy to obtain with one of the largest sources being oily fish. The balance between omega-6 and omega-3 is thought to be key for good health with an ideal ratio being around 3:1; the current western diet is thought to be around 16:1.9 One of the main reasons for this is because the UK population as a whole does not eat enough fish, especially the oily varieties such as salmon and sardines.10 The common food sources of omega-3 and omega-6 are summarised in Figure 1 (Distribution of omega-3 and omega-6 in common sources).

One of the easiest ways to address this imbalance is to supplement with omega-3. Table 1 provides a summary of the literature showing the impact of omega-3 supplementation (Table 1: An overview of the impact of omega-3 supplementation on dry eye). 

Figure 2

The significance of dry eye type

Dry eye disease is a multifactorial condition and there are many different types (see Figure 2: Types of dry eye). Management needs to be tailored for the type of presentation - treatment for a patient who is aqueous deficient will be different from a patient who has evaporative dry eye. Studies suggest that meibomian gland dysfunction (MGD) is the leading cause of dry eye disease,19 with some suggesting that it could account for over 85% of the cases.20 A summary of the literature which considers the impact of omega-3 in the management of MGD is provided in Table 2 (Table 2: Overview of literature on the effect of omega-3 on meibomian glad dysfunction).

Options for supplementation

One way to supplement levels of omega-3 is to increase the amount of oily fish in the diet and having a hand out available for patients to take with them regarding this is useful. Not all patients will want to increase their fish intake, and this is where nutritional supplements can play a role. Some clinicians prefer to direct their patients to the nearest supermarket or health store, and allow them pick their own omega-3 product; this can mean that patient’s fail to source these products after they have left the practice. Suggesting a specific product is better, and stocking a supplement in practice can help improve the likelihood of uptake. 

While all supplements have the potential for toxicity, suggesting a supplement specifically designed for eye health can reduce the chances of the patient self-selecting a very high dose supplement. 

Table 1

Eye-specific supplements 

While omega-3 is clearly the most effective nutritional for dry eye it is not the only nutrient to consider. Studies have shown that antioxidant vitamins and minerals can improve dry eye symptoms,25 and may play a role in preventing omega-3 supplements from becoming rancid. A recent study found that omega-3 enriched eggs were much more stable when antioxidants were also present.26 Many dry eye specific supplements incorporate omega-3 and antioxidants for increased stability and improved absorption. Further, fish oil alone does not address the role of oxidative stress in tear film dysfunction, and some additional nutritional formulations have been designed that incorporate both fish oil and nutritional co-factors.27 

Available products 

There are many products available designed for eye health and some that focus on dry eye specifically. Deciding on the brand will depend on individual research and personal preference. 

While a lot of studies have used high concentrations of omega-3 such doses are typically not available in eye-specific products. As a result, significant improvements to the clinical picture may not be apparent until three months after commencing treatment; this will depend on the patient’s dietary levels to begin with. It is, therefore, a good idea to review patients after an appropriate period of time to allow for the supplements to have their desired effect. 

Table 2

Conclusion 

The role of optical professionals is ever expanding. This can be quite daunting and is perhaps one of the reasons why supplements have not played a bigger role in the treatment of dry eye disease. With the increasing incidence of DED ensuring our patients receive treatment has never been more important. Adding nutritionals to our ever expanding arsenal of tools for the treatment of dry eye could have a big impact on our patients’ well being. 

About the author

Iain Johnson is a dispensing optician with additional expertise within the field of nutrition. He has written articles relating to nutrition and eye health for publication and lectures on the role of nutritional supplements within optometric practice. 

References

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