The causes

• genes
• healthy lifestyle & exercise
• smoking
• blood pressure & exercise & weight
• diet
• Vitamin supplements
• Oily fish
• cholesterol
• statins
• cataract surgery (another page)

pathology

• invisible changes
• What does a person notice with these early changes

types of dry ARMD

• atrophic ARMD
• drusen
• soft drusen
• diagram..drusen
• geographic
• foveomacular dystrophy
• Choroidal Sclerosis
• mixed/retinal pigment epithelial hypertrophy

Notes

• links
• Macular Disease Society
• BMJ article   a slide show
  

Age-related macular degeneration is explained in more detail on other web-sites, such as the RNIB and NIH. This is an excellent animation: www.eyesight.org. Below is a brief description.

Age-related macular degeneration (ARMD) is usually a progressive condition.

Dry ARMD progresses over many years. See dry ARMD page. Sight does deteriorate, but most people manage to cope well, although reading is difficult and life may be different. In sime types of dry ARMD progression may be very slow, but it may be quicker in other types.

Dry ARMD may progress to the 'wet type', but this is not always the case.

Wet ARMD  begins as new vessels growth in the macular area, causing retinal leakage and swelling. See wet ARMD page. It progresses to cause a scar in the macular area. If the scar is small, sight is reasonable; if large, the sight can be very poor.

Imagine your retina has five layers. Normally this retinal appearance stays constant even in old age, but changes may develop as you get older.

As we get older, changes develop in the retina. The bruchs membrane thickens and the choroidal blood vessels change.

The thickened bruchs membrane prevents waste products leaving the retina (see animation and the link), and also prevents nutrients entering. This is thought to be a direct cause of the condition. Lipofuscin (type of fat) accumulates in the retinal pigment epithelium; this damages the pigment cells which eventually die.

The choroidal circulation changes...the blood vessels become larger but fewer. This is probably mainly due to a 'hardening of the arteries' that happens elsewhere in the body, particularly with a Western diet.

The invisible changes progress to cause dry ARMD,

• patches of extra thin retina develop, just as though the retina is 'worn out .  Often the patches of thin retina gradually get larger, reducing sight.
• Deposits of waste products may develop, called drusen
• pigment changes develop
• the dry changes may convert to 'wet ARMD'

These changes are described with photos below.

• difficult seeing in dim light
• difficult seeing in bright light
• slow recovery in bright light
• poor central vision when you wake up

If you notice these problems then you are probably at risk and need a check from an optometrist or ophthalmologist. If there are no visible changes, the author would strongly recommend a healthy lifestyle as prevention...it helps your general health in any respect. (This section: after Prof. Bird).

• atrophic ARMD
• drusen
• soft drusen
• diagram..drusen
• geographic
• foveomacular dystrophy
• Choroidal Sclerosis
• mixed/retinal pigment epithelial hypertrophy

The retina becomes very thin, just as though it is worn out. The patches of such thin retina do not 'see', so the central vision becomes patchy. Essentially it is a type of wear and tear.

Atrophic changes are present in most of the of the 'dry' types of ARMD as below.

Dry types of macular degeneration can get very slowly worse, but only affect the macular area. The rest of the retina, which helps you see at the sides so you can walk round the house, always stays good.

This movie  is excellent.

If this wear and tear is mild you may be able to read and even drive, although it takes a little longer to adjust to different lighting.

Often it is a little more severe, and reading is difficult, and driving is impossible. TV is not too bad if you sit close: this is discussed in Hints & coping.

Dry ARMD may progress to cause more damage to the central retina'; this is a usually a very slow process taking years. Some types are non progressive, and not discussed here in detail (such as old macular holes).
Every person is different, and often it is very difficult for your doctor to predict what will happen to your sight.

Sometimes changes can occur more rapdily, and this would suggest that you are also developing the 'wet' type of ARMD as below. See www.macula.org .

see photo

Patchy vision in atrophic macular degeneration

Drusen may develop. These are accumulations of material, probably some waste products of the retinal cells. These are common, and do not usually affect the sight.

The accumulation occurs as bruch's membrane becomes thicker and prevents the free flow of materials to and from the light or photoreceptors layer.

Also, the retinal pigment cells accumulate liposfuscin. This pigment will also slow down the passage of chemicals to and from the retina.

Some people with a lot of drusen do have slightly reduced sight.
Drusen look like little white spots in the retina. See tiny drusen.

Hard drusen: If they are well defined with a sharp edge, the sight is likely to stay good.

Soft drusen: If they are a little like cotton wool, they are more serious as they may lead to more serious disease with 'exudative changes' as below: prevention is most important (see above). Reference.  

If there are a few drusen you may be said to have very early 'dry' macular degeneration.

See types of drusen,  risks and epidemiology. Soft drusen are inherited: see CFH Y402H.

see a retinal photo
and confluent soft drusen
and another. and another large one. another

See hard drusen (right) & case.

drusen

Areas of thin retina develop. These areas form like the patterns of countries of the world. The areas get bigger (over years), slowly causing more damage to the sight.
Geographic atrophy is the main type of dry ARMD. See a photo. another   another  

We now know here that the risk of passive smoking (doubles the risk) and personal smoking (triples the risk) of both geographic atrophy. See genes and here.

Geographic atrophy (GA) accounts for a third of ARMD, with new 12,000 cases a year. It is believed to be caused by retinal pigment epithelial atrophy leading to cell death. It is best examined with the autofluorescence technique but this is seldom available. There is not treatment available yet, although trials are in place.

Myopic macular degeneration is usually similar.

If the damage is in a very small central area, this may be the type described by Gass, and here foveomacular dystrophy , and will not progress.

See a photo.   another

If there is a large thinned area this may be the ‘choroidal sclerosis’ type of ARMD. This often affects both eyes, but is not treatable, often causing poor central vision.

The thin area actually looks white, and the thick choroidal blood vessels can be seen underneath. Photo.

Changes may include thinning of the retina, drusen, pigmentation, or thickening of the retina. There is a variable outcome. ‘Prevention’ may help.

photo     photo    photo

Dry ARMD may develop into 'wet' ARMD (4%/year). In wet ARMD, leaks develop, and new vessels start to grow right through the retina.

Occasionally wet ARMD develops without dry changes, although usually there is an area of retinal damage that triggers the process. photos

Wet ARMD progresses 4 times faster (a 400% increase in progression rate) in smokers.

How would you know if you have the 'neovascular' type of age related macular degeneration?

Some symptoms suggest you may be developing the problem

• distortion of vision, where straight lines such as window frames appear bent as shown below See diagram
• a feeling as though you are looking through water

If you do develop distortion of vision you usually need to see your ophthalmologist reasonably soon. In the UK you may need to discuss this with your GP, or in a large city attend the Eye Emergency department.

Your ophthalmologist may recommend tests such as a fluorescein angiogram. The angiogram tells the doctor if there are new vessels, where they are, what type they are, and what type of laser if any will help.

Patients should probably be given the Amsler Grid test to use every day, or at least once a week, at home. These authors recommend this test, although personally I have found that patients may still present late.

Patients are given a grid, told to look at the central spot with their reading glassses on, using one eye at a time. If any of the adjacent lines become bent or wiggly or distorted, then CNV (blood vessels growing under the macula) may be present, and patients should see their ophthalmologist (in Birmingham attend the Eye Centre Casualty, City Hospital).   The test is explained well here .

Distortion of straight lines which may start to appear crooked over a few weeks usually means the ARMD is progressing.

Sometimes this is due to the 'neovascular' ARMD developing, and you are advised to be checked in case laser may help.

• The atrophic or dry type usually does occur in both eyes, but remember this generally gets very slowly.
  
• There may be a gap of years before the process begins in the second eye.

http://www.nei.nih.gov/health/maculardegen/armd_facts.asp

http://www.visudyne.com/index.jsp ....for patients (needs enrollment)

http://www.visudyne.com/hcp/index.jsp for professionals

http://www.maculardisease.org

info@maculardisease.org     ARMD web site http://www.armd.org.uk/index.html

The Macular Disease Society
PO Box 1870
Andover
SP10 9AD
Tel: 01264 350551

thanks