Macular Degeneration

Macular degeneration is an age related medical condition which usually affects older adults.  It occurs because of damage to the retina that results in loss of vision in the centre field of vision “the macula” and occurs in “wet” and “dry” forms.  Macular degeneration is the major cause of vision impairment in adults over the age of 50 years, and can make it difficult to recognise faces or read.  But enough peripheral vision remains which allow the adult to continue with other activities of daily life.  Some types of macular dystrophies can affect younger individuals and can sometimes be referred to as macular degeneration, the term is usually reserved for age-related degeneration.

The retina which contains the nerves that communicate sight which are located in front of the choroid which supplys the blood to the macula (central part of the retina). In the “wet” form of macular degeneration which is often more severe, the blood vessels grow up from the chororid behind the retina also causing it to become detached.  This maybe treated with laser coagulation and combined with medication can halt and sometimes reverse the growth of the blood vessels.  In the “dry” form of macular degeneration cellular debris accumulates between the choroid and the retina cause the retina to become detached.

Often an early sign of age-related macular degeneration begins with yellow deposits in the central area of the retina (macula), even with these early changes they can still have adequate vision, but can go on to develop advanced Age-related macular degeneration.  Some recent research has suggested that drusen (debris) are related to elevated cholesterol deposits and some treatments such as cholesterol lowering medication can be beneficial.

It is important to note that advanced age-related macular degeneration while responsible for vision loss typically never leads to total blindness.

Web age-related macular degeneration – Irreversible damage to the photo-receptors and rapid vision loss can occur if the bleeding, leaking and scarring affects from the blood vessels are left untreated.  No effective treatments were available before new drugs can Anti-angiogenics were made available as they can cause improvement of vision when directly injected into the viterous humor of the eye causing the regression of abnormal blood vessels.  Some of these agents are known as Lucentis (ranibizumab), Macugen (pegaptanib) or Avatin (bevacizumab).  Lucentis is the more expensive treatment at around $2000 US dollars per treatment while Avastin is around $150 US dollars per treatment, but both drugs are made by the Genetech group.

Dry age-related macular degeneration – While no treatment is available for this particular condition, high doses of antioxidants, lutein and zeaxanthin taken as part of vitamin supplements have slowed the progression of dry macular degeneration and in some patients have shown improved visual acuity.

Signs & Symptoms of Macular Degeneration

  • Pigmentary alterations
  • hemorrhages in the eye
  • hard exudates
  • visual acuity drastically decreasing
  • blurred vision
  • distorted vision
  • a lost in contrast sensitivity
  • trouble discerning colours
  • shadows or missing areas of vision (central scotomas)

One of the simplest and most effective methods for patients to monitor the health of the macula is the Amsler Gird Test, which is a pattern of intersecting lines with a black dot in the middle. The central black dot is used as a fixation point for the patient to stare at, and with normal vision the all the surrounding lines will look evenly spaced with no odd looking areas of bent distorted or missing lines.

The reason that macular degeneration doesn’t lead to total blindness is that the macular area comprises 5% of the retina and is only responsible for 35% of your visual field, so your peripheral field will remain unaffected by the disease.  Other tests that measure loss of contrast sensitivity can be easily measured by a contract sensitivity test performed at home or in your eye surgeons office.

Causes of Macular Degeneration

Aging: 10% of patients ages 66 to 74 and increasing to 30% of patients aged 75 to 85 years old will find macular degeneration

Family history: 50% for people that have a relative with macular degeneration a fourfold increase in risk

Hypertension: factors such as very high blood pressure

Cardiovascular status: factors such as obesity, high cholesterol

Smoking: factors are increased by around two or three times more than someone who hasn’t smoked

Management of Mascular Degeneration

Typically vitamin and mineral supplements had no affect on the general population who had age-related macular degeneration, but consumption of Omega-3 fatty acids has be tied to reduced progression of age-related macular degeneration when the diet also includes low glycemic index foods.

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