WHAT IS AGE-RELATED MACULAR DEGENERATION - AMD?

The macula is the small central area of retina where most cone-shaped photoreceptor cells are found, being  the area where the maximum visual acuity occurs - central vision, shapes, colours, distinguishing fine detail.

Images in detail are perceived in the macula, the central vision being needed for activities such as: reading, driving motor vehicles, recognizing people.

Age-related macular degeneration (AMD) is the leading cause of central vision loss in the elderly over 65 years (risk of AMD increases with age from 50 years, causing 30% of patients over 70 years to have signs of the disease). Since AMD does not affect peripheral vision, complete blindness does not appear, however at distance and close the central vision is affected. The disease is usually bilateral, but initially affects only one eye, and will also affect the other eye in time, stages of evolution being different between the two eyes.

WHAT CAUSES AMD?

Causes that determine AMD are not known, but we can speak of a number of risk factors that increase the likelihood of onset. There are a number of unmodifiable factors like age, family history, race (whites have higher risk), ocular pigmentation (those with light coloured iris are at increased risk), hyperopia (seems to be associated with AMD), and a number of modifiable factors: smoking, obesity, hypercholesterolemia, high blood pressure, cardiovascular disease, diet low in carotenoids, antioxidant vitamins (vit. C, vit. E) and minerals (zinc, copper, selenium).

WHAT ARE THE TYPES AND SYMPTOMS OF AMD?

The first signs of the disease may be blurred vision, straight lines perceived as crooked, central vision disorders. There are two clinical forms of AMD:

  • Dry (atrophic) in 85% of cases
  • exudative (wet, neovascular) in 15% of cases, the latter causing in 80% of cases rapidly and severely lose of central visual acuity;

The dry form is initially asymptomatic, with simple functional abnormalities unnoticed by the patient such as decrease in contrast sensitivity, decrease in dark adaptation, decrease in central sensitivity, colour vision abnormalities. Clinically, it translates into the need to increase lighting when reading, vision centrally blurred with inability to perceive figures from the distance.

In the wet form some abnormal subretinal vessels appear, neovessels that bleed easily, lose fluid through the vascular wall that accumulates under retina and causes, in advanced stages, fibrous scar tissue that will cause changes in shape of the macula, sending distorted signals to the brain. Straight lines are becoming wavy, curved, and objects can be seen smaller or larger than they actually are. In the centre of the image black spots (scotoma) appear, which become larger as the area affected grows.

Since peripheral vision is not affected, the patient is not completely blind which allows him carrying out activities of daily living (moving in his/her environment, eating, dressing), but he/she will not be able to read or write, and he/she cannot recognize people on the street or do things that involve details.

WHAT IS THE TREATMENT FOR AMD?

For the wet form of the disease there is at the moment a treatment which seems to be effective. The treatment consists of intraocular injection, in sterile conditions (operating room) of a substance called Avastin. The intervention is extremely easy for the patient and the risks are minimal, it is done with local anaesthesia and without hospitalization.

For patients whose view remains low even after treatment, there are visual aid devices. These devices help many people with AMD to read, look at pictures, etc.

As a novelty, presently there is such a portable visual aid device available for patients in Romania. The device is small and can be used when the patient is shopping and travelling.

It is important that after a certain age annual ophthalmologic consultation be performed to try preventing, slowing the progression or treatment of conditions that can occur many times without any obvious signs. The ophthalmologic consultation should necessarily include visual acuity testing, intraocular pressure measurement, pupil dilation for the fundus examination, visual field examination and for AMD the Amsler test.

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