The MPS ll as part of your macular screening programme

Published: 12-Oct-2016

What does a larger and more aged population mean for our approach to eye health?

Growing evidence suggests that a radical rethink is needed to tackle the threat posed by age-related macular degeneration … but it’s a fight we can win.

Age-related macular degeneration (AMD) is the most common cause of vision loss in the global aged population. Rather than simply causing blindness, it affects the macula, part of the eye’s retina, damaging central and peripheral vision to varying degrees with time. Those suffering from AMD can often make out what they’re looking at, but fine details become difficult to spot, especially in the case of direct central vision in advanced cases.

In the UK, the disease accounts for 50% of blind and partial sight registrations. In Asian populations, the figures are similar, whereas in African and Hispanic communities, this risk seems to be lower. Further study is needed to look at other populations and the effect of geographical location within the same country, comparing rural to urban, or any changes in diet (traditional to Western). Given the role of proper supplementation when it comes to managing the disease, the latter factor is likely to be significant.

AMD is a complex disease, subdivided into non-exudative (dry) or exudative disease (wet) varieties. Dry AMD is the most common, accounting for 80–90% of all new cases. The prevalence of AMD in the UK is 2.4% by the age of 50, rising to 12.2% at age 80 or older. With the predicted demographic shift bringing increasing numbers of elderly citizens, these figures are expected to reach much higher levels by 2020.

Research also suggests that AMD is affecting people at a far earlier age than previously thought. Statistics from Germany show that within a patient group of 4340 participants, 3.8% of patients aged 35–44 already showed early signs of AMD. This contradicts previous wisdom on the matter and makes a compelling case for screening at an earlier age, at least less than the traditional 40 years if not for all persons older than 16.

At present there is no treatment for dry AMD, and wet AMD cannot develop without the former. If dry AMD is allowed to progress through its various stages, wet AMD is 14–20% more likely to develop in 5 years. Clinicians and community members greatly underestimate the impact of mild, moderate and severe AMD on a person’s health-related quality of life. Indeed, many patients in this stage of the disease report that communication was poor and depression and anxiety has evolved.

So, given the aggressive nature of the disease and the earlier, broader spread, eye health professionals are faced with a critical task. It is important to identify those at risk, employ a screening programme using evidence-based methodology and manage every patient appropriately.

AMD risk factors

Many risk factors are associated with AMD, classified by their severity. High risk factors include low macular pigment, smoking, being older than 50 and having a family history of AMD. Medium risk influencers include exposure to 'blue light,' Caucasian ethnicity and clear intraocular lenses (IOLs). Low risk contributors include obesity, high cholesterol, systemic hypertension, excess exposure to the sun and vitamin D deficiency.

The MPS ll as part of your macular screening programme

Some factors are modifiable, some are not. It’s worth noting that the blue light hazard has increased with the number of people now using technology such tablets and smartphones on an almost constant basis. In addition, many patients are being implanted with intraocular cataract lenses (IOLs) as a routine part of cataract surgery, which do not contain a yellow filter to absorb blue light.

Combined with an older patient base and the advancement of surgical procedures to allow nearly all patients a choice of cataract surgery, it’s not hard to see the problem.

What is MPOD?

Although treatments have been developed for wet AMD, at best they delay or stop the progression of further visual loss but do not restore sight to and are not without their own complications. However, studies show there is finally some good news for patients with dry AMD. By taking supplements to build up their macular pigment optical density (MPOD), it’s possible to halt the progression of the disease.

From a socio-economic standpoint if nothing else, it is no longer a viable option to wait for patients to develop wet AMD

MPOD is the concentration of macular pigment, made up of lutein and zeaxanthin, which serves as the eye’s natural protection against harmful blue light. Although blue light may only be listed as a medium-level risk factor compared with some others, its overwhelming presence in the modern world makes it only likely to get worse with time and cultural changes.

Low MPOD can occur long before (and continue to get worse long after) symptoms of AMD are felt. It therefore makes sense for eye health professionals to promote a proactive approach to maintaining healthy MPOD as soon as they first come for screening. The MPS ll, the screening device commonly used for published studies on AMD, measures MPOD with a score from zero to one. One is obviously the most desirable, although even a score of 0.75 is classed as very good with no need for intervention. The average score of those screened ranges from 0.33 to 0.36.

When an MPOD reading is taken using the MPS ll, the eye care professional needs to understand how best to leverage this reading to create an AMD prevention or management strategy that best fits the patient. When an individual’s risk of AMD is dependent on the interplay of multiple variables, a supplement regime needs to take into account both the MPOD reading and the other cumulative risk factors. Building up MPOD during the decades before AMD is likely to develop will provide far greater protection against blue light, making the retina less susceptible to damage.

The role of supplementation

It is now 13 years since the publication of the original AREDS study, in which it was shown that the use of general antioxidants, vitamins C, E and beta-carotene in combination with zinc, reduced the risk of AMD in some patients by 19%, or advanced AMD or vision loss caused by AMD in one eye by 25%. Long-term use of AREDS-approved supplements appears to be both safe and protective, with long-lasting effects.

Following on from the study, laboratories began to synthesize the carotenoids that make up the eye’s macular pigment, such as lutein, zeaxanthin and mesozeaxanthin. MPOD is entirely a matter of diet, with mesozeaxanthin formed in the retinal tissue with lutein. In 2013 came the publication of AREDS2. This was a huge trial of 4302 patients at high risk of advanced AMD, designed to assess the effects of supplementation on the progression of the disease.

The MPS ll as part of your macular screening programme

An additional goal of the study was to assess whether a new form of the AREDS nutritional supplement with reduced zinc and/or no beta-carotene would work as well as the original supplement in reducing the risk of progression. AREDS2 clearly showed the benefits of this new formulation, with a 26% reduction in the risk of progression to advanced AMD beyond the effects of the original supplement.

In fact, it found that beta-carotene actively competes with lutein as an antioxidant and should be removed from formulations. In patients who smoke, it also increased the risk of lung cancer, making it clearly undesirable.

To give some idea of context, trying to obtain the same benefits from green vegetables alone would require approximately one whole kilogram of broccoli to be eaten every single day. Today, these supplements are available over-the-counter in many countries such as the UK and, in Europe, are widely available on prescription. When supplements are started, they should be continued no matter how high the MPOD score becomes to protect the retina against the blue light hazard. If the regime is discontinued, levels will fall with time.

In conclusion

AMD is affecting people at a far younger age than previously thought, which in turn means that it is vital to screen patients early to identify those most at risk of developing AMD. By measuring macular pigment and identifying all other risk factors that may be present, appropriate preventive management strategies can be implemented.

From a socio-economic standpoint if nothing else, it is no longer a viable option to wait for patients to develop wet AMD. Treatment is extremely costly, outcomes are varied and people’s quality of life is severely impaired at this late stage. Screening people early for low MPOD and increasing pigment with time is a strong insurance policy against sight loss.

Supplementation has also proved to be effective for those many millions of patients worldwide who have dry AMD, demonstrating that the combination of MP screening and supplementation is a viable preventative strategy for AMD.

Screening on the MPS ll is a simple test that can be performed by support staff and does not require the patient to take eye drops to dilate the pupils. The test is non-invasive, quick to perform and provides instant results that can be fed into a comprehensive management programme.

The challenges that the future will bring us in terms of caring for an ageing population are many. Thankfully, the technology to identify, screen and protect more people than ever from a leading cause of sight loss is in our hands. The time to act is now.

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