What is the Macula?
The macula is the centre of the retina (a film of tissue lining the inside wall of the eye, and which is essential for vision).  The macula is the most sensitive part of the retina [see figure 1], and is responsible for colour vision and detailed central vision.  The macula allows us to perform tasks that require good central vision such as reading, watching television, recognizing faces and driving.

Figure 1

Visually consequential age-related macular degeneration
Visually consequential age-related macular degeneration (AMD) is a disease of the macula that results in loss of central vision.  AMD is the result of abnormal blood vessels growing behind the retina [see figure 2] and/or atrophy (i.e. disintegration of the retina and choroid [see figure 3]).  AMD is the leading cause of age-related blindness in the western world, and is becoming increasingly prevalent throughout the world.

Recent figures demonstrate that, in the developed world, AMD accounts for over 50% of cases of registered blindness.  As its name suggests, the prevalence of AMD rises with increasing age, and therefore the prevalence and incidence of this disease are on the increase because we are living longer [see figure 4].

Figure 2	Figure 3

Figure 4a

Figure 4b

Figure 4c

What happens if you have visually consequential AMD?
AMD is particularly frustrating because (if untreated or untreatable) it results in a loss of central vision. In other words, someone with AMD can see everything except what he/she is looking at, and is therefore unable to read, watch TV, recognize faces or drive. AMD dramatically reduces an individual’s quality of life.

Fear of Blindness
When asked what health condition they fear most, one third of people will say blindness, another third will say cancer, and the final third will cite a wide range of ailments or fears. However, most people regard it unlikely that they will develop blindness or vision loss. It is worth emphasising that even small degrees of visual loss have major adverse impacts on the quality and length of life.  For example, vision of 6/12 (about 83%) or less is associated with loss of driving licence; increased risk of falls, hip fractures and depression; loss of social independence; admission to nursing homes three years before their counterparts with normal vision; not to mention, perhaps most importantly, a reduced ability to enjoy healthy and independent ageing.

What causes visually consequential AMD?
Although the exact cause of visually consequential AMD remains uncertain, it is known that damage by free radicals within the eye plays a role.  Free radicals are unstable molecules produced in response to a person metabolising oxygen, and in response to light entering the eye.  Because we use oxygen to live and because we are constantly exposed to light, damage caused by free radicals is unavoidable.

What are the symptoms of visually consequential AMD?
The main symptom of visually consequential AMD is dim or fuzzy central vision, which can affect the ability to carry out fine detail visual tasks such as reading.  With this disease, objects may appear distorted or smaller than they really are. Faces will become more difficult to recognize. As the disease progresses, central vision is totally lost.  However, good peripheral (navigational) vision is retained.

Test your vision for signs of AMD

• Hold the grid at eye level at a comfortable reading distance.
• If you wear reading glasses, wear them during the test.
• Cover one eye at a time, and focus on the centre dot in the grid.
• If you notice any of the potential signs of AMD like wavy, broken or distorted lines or blurred or missing areas of vision, contact your healthcare professional immediately.
  

Top