Good Hope, Heartlands, and Solihull Eye Clinics

Age related macular degeneration:
contributory factors

David Kinshuck

ARMD introduction

ARMD is an aging change or wearing out of the central retina. It causes loss of central vision. This makes reading and driving difficult. Later, if it gets more severe, it becomes difficult seeing faces, crossing roads, and cooking. The peripheral or side vision always remains, so even if the central vision is poor, it is always possible to see and get round the house and see to the side.

ARMD is usually a progressive condition. Invisible early changes occur, then usually some type of dry ARMD, such as drusen. Later, the dry changes may progress, usually slowly, to cause geographic atrophy and thinning of central retina. These are all termed part of 'dry' ARMD. Treatment for geographic atrophy is awaited.

A secondary change may then develop in some people, as the body tries to 'heal' the changes. Blood vessels may start to grow in the centre of the retina in the macula area. The blood vessel growth causes leakage and scarring, and is termed 'wet' ARMD. These wet changes can be slowed down with anti-VEGF eye injections (wet ARMD page).

This page summarises our current knowledge. Age-related macular degeneration is explained in more detail on other web-sites, such as the RNIB and NIH. An excellent animation: www.eyesight.org.

 

Contributing factors: aging, genes, diet, smoking, etc

Age-related macular degeneration (ARMD) is one of the commonest causes of poor sight in developed countries. Whilst the causes are different in different people, certain factors may contribute. The main factor is age. 

"By age 85, 57.4% of [people have] AMD. Age, smoking, plasma HDL cholesterol, BMI, and female sex are associated with AMD. Elevated HDL cholesterol is associated with GA development."  .Oph 14

 

age Age is the main factor.
smoking

Contributes 32% overall, even passive smoking. BJO 17.
'Just one cigarette a day seriously elevates cardiovascular risk ' BMJ18, so it is best to stop completely.

diet related up to ~30%; a high cholesterol from an unhealthy diet or genes Klein (2010); Toothbrushing helps. (tooth decay promotes conditions such as rheumatoid arthritissummary  BJO16  
blood pressure High blood pressure damages the circulation...target is 140 systolic in clinic, 10 lower for diabetes. 10 lower at home. 120 at home for diabetes. Best below 120    2 medications often required.
exercise

;reduces progression to neovascular ARMD by 70%     AJO17

genes ~50% is directly due to the genes we inherit Gene page
cholesterol a high fat diet 10% (2010)
airbourne pollution This causes cardiovascular disease, and will contribute to macular disease. In urban environments, ~8% of deaths are generally attributed to pollution BMJ 14
alcohol Excess alcohol is also related to ARMD, see 
sunlight Strong sunlight contributes to ARMD; and sunglasses protect, see.  But gentle sun exposure increases vitamin D production, and this will reduce the risk of many conditions such as diabetes, osteoporosis, and prostate cancer. Retina16
inflammation Chlamydia  high CRP, dental caries, each contribute
macular pigment Light skin increases risk Eye 2012.
obstructive sleep apnoea Untreated obstructive sleep apnea hinders response to bevacizumab in age-related macular degeneration  Retina 16     BJO 17
Oral Bisphosphonates AJO 16     2-4x risk
Choroid BJO 17

 

Other countries

pie chart illustrating factors contributing to ARMD

enlarge

 

Some communities in Japan did not develop macular degeneration as people aged, but as soon as they started eating Western food the condition started to occur. Similarly, when Japanese people move to Western countries, they develop the condition more frequently.

These observations suggest that the high fat, and type of fats, such as saturated and trans-fats, the lack of protective fats (omega 3s, from fish), and salt (by increasing blood pressure) increases ARMD. Lack of exercise as we drive everywhere in Western countries will contribute.

 

Genes

We inherit these from our parents. Genes are the genetic information that tells our body what chemicals to make. Overall, our genes may contribute to more than 50% of ARMD. The main genes have been found. Gene page.   For example, these genes control the way used-up chemicals are removed from the eye. Being long-sighted (hyperopic) is also a risk factor

 

A healthy lifestyle

A healthy lifestyle helps to prevent age related macular degeneration. This is important for the younger relations of age related macular degeneration sufferers:

 

Smoking

smoking increase the risk or ARMD 3-4 times

 

the risk of smoking and passive smoking and ARMD

larger

  • Overall smoking accounts for 32% of ARMD. Even stopping at the age of 80 will reduce the risk of developing the disease. So if you have a relation with macular degeneration, try and stop as smoking may make it develop earlier.
  • Smoking increases the risk of macular degeneration about 3 times. Macular degeneration occurs 10 years earlier in smokers.
  • If you have macular degeneration, do try and stop. Even if you are 90 years old stopping smoking will help your eyes considerably.
  • Passive smoking is also harmful: for instance, if your partner smokes cigarettes a day, you receive 25% of the smoke, so that is equivalent to you smoking 5 cigarettes a day. 28000 cases a year in the UK. See 2002 report and 2003 study . Lithuania     Japanese    China  
  • Passive smoking doubles the risk  ,  personal smoking triples the risk of both geographic atrophy and neovascular ARMD.
  • Each cigarette increases the ARMD progression rate ~15%.

 

Blood Pressure & Exercise

dancing and all other forms of exercise delay ARMD

 

  • 30 minutes a day at least, walking, or more active exercise for younger people,  reduces risk by 70%: 2006
  • Exercise may help by preventing hardening of the arteries. 30 minutes walking a day (regular walking) three times a week will reduce ARMD risk by one third, compared to people who don't walk or exercise and who drive everywhere.
  • A low blood pressure helps. A level of 140/85 or below is likely to be best. Blood pressure is written as '140/85', with the systolic/diastolic. Above 115 (systolic) the risk of heart disease increases. See the evidence and more. Macular haemorrhages are more likely with high blood pressure. More evidence Eye.
  • Obesity is also a risk factor see. 
  • A low salt diet is important Salt and more than 2 units of alcohol a day may cause blood pressure to rise.

Alcohol

 

after 8 units of alocohol blood pressure rises for 2 days

enlarge

Too much may contribute indirectly by increasing blood pressure, and is related to ARMD, see.

Blood pressure rises after drinking (opposite...drinking 4 pints/bottle of wine).

Each gram of alcohol puts systolic blood pressure up 0.24mmmHg, diastolic 0.16 mmHg. This means 1 pint of beer (2 units, each unit 8g alcohol) with 16gm of alcohol, drunk every day, will put the systolic blood pressure up (16 x 0.25=) 4mmHg.

 

Diet

Experts recommend a healthy diet.

fruit and a healthy diet will sigificantly reduces the risk of developing ARMD

7 portions of vegetables a day and 2 portins of fruit, with portions of different colours

 

 

Fruit/vegetables prevent 36-50% of ARMD see, see and see (fruit & vegetables lower homocysteine levels, and this improves blood flow) BMJ 15. Pulses like beans are fine. Bread, pasta, rice and potatoes provide 'energy'. Vegetarians have lower blood pressures and healthier lipid levels,  see . A healthy diet reduces homocysteine levels, which are associated with ARMD. Certainly saturated fats increase the risk of ARMD; and fish and polyunsaturated fats halve the risk. Avoiding certain fats helps, with strong evidence here (explained more clearly here for heart disease). Nuts may help prevent ARMD (small amounts...they are fattening).

Vitamin supplements

Age-Related Eye Disease Study--Results

Lutein and Zeoxanthin  supplements slow down progression on average 10%, AREDS 2, 20% if diet is poor.

As the macula is the most chemically active area in the body, with the greatest oxygen demand, it has been thought that antioxidants such as vitamins may play a critical role. The retina contains the pigments carotenoids lutein, xeaxanthin, mesoxanthin.

Lutein is in dark green leaves such as kale and spinach, and most of us do not eat enough. Xeaxanthin is in orange peppers, corn, nectarines and oranges (and other yellow/orange fruits/vegetable). "Higher dietary intake of lutein/zeaxanthin was independently associated with decreased likelihood of having neovascular AMD, geographic atrophy, and large or extensive intermediate drusen" Seddon.  No need Cochrane 2017.

References

 

Oily fish

oily fishes reduces ARMD  ~40%

Oily fish twice a week reduces ARMD by 40%, especially oily fish such as tuna, mackerel, sardines, herring, and salmon. A Japanese diet may be helpful as above. Other omega 3 fats are helpful. See

 

Cholesterol & statins, patient and relatives

Statins

Statins benefit

no benefit

ARMD is commoner in people with higher cholesterol levels. Atherosclerosis, caused by a high cholesterol, does contribute to ARMD, see .  Statin treatment reduces macular degeneration. DK recommends them for people with ARMD.   Naturally all relatives of ARMD patients should address this issue of fat levels in the blood, sticking to a low fat diet with plenty of exercise, avoiding obesity, just as described on this page for ARMD patients. Statins may not help

 

 

Macular pigment

Macular pigment density is inversely related to ARMD: the thicker the pigment the less likely the condition.

  • this explains why the condition is much commoner in Caucasians with blond hair and lighter coloured retina
  • increasing the pigment with lutein may delay the condition Acta 2012  Eye 2012
  • ARMD is unusual in Afro-Caribbeans, and this may be because the 'elastin' layer is thicker.
  • Especially in wet ARMD with CNV, the elastin layer acts as a barrier to the growing CNV (new vessels). Elastin is part of Bruchs membrane link.

 

Cataract surgery and Vitreous changes

cataract

One paper suggests cataract surgery leads to an extra 4-5 times risk of developing neovascular macular changes or dry ARMD. Another states this is not so AREDS 25. Certainly patients with early ARMD undergoing cataract surgery should be warned of symptoms, that is distortion or changes in central vision, and attention should be sought in a few days. Also.

If the vitreous is separated from the macular the risk of CNV is significantly reduced AMJO 09.