Introduction  

Macular degeneration is a disorder characterised by a deterioration of the retina.  The retina records images and sends them to the brain. This condition affects the central part of the retina, the macula. 1 in 2,000 individuals in the U.S. and other first world countries suffer from AMD.
The macula's role is to focus the eye's central vision thus controlling the ability to read, recognize colors and faces, see objects, and drive a vehicle. When this part of the retina degenerates, the affected person loses their vision.

AMD occurs in three stages:

  • Early AMD
  • Intermediate AMD
  • Late AMD

During the first stage, vision loss is rare. In the intermediate stage, some people experience vision loss; however, the symptoms may still go undetected. In the late stages, vision loss is much more noticeable.

Also Known As

  • Age related maculopathy
  • AMD
  • ARMD
  • Macular degeneration, age-related
     

Sub-Types

There are two variations of macular degeneration; dry macular degeneration and wet macular degeneration. Wet macular degeneration is further classified into two; occult and classic.

Causes and Risk Factors

The primary factors that contribute to macular degeneration remain unclear. The most probable causes are genetics and environment.
Research has associated AMD with a gene called complement factor H or CFH. A high percentage of macular degeneration incidences are attributed to the CFH gene. Other studies have suggested that another gene known as complement factor B causes the progression of AMD.
Another study has associated AMD with oxygen deprived cells. These cells produce a protein known as vascular endothelial growth factor or VEGF, which promotes new blood vessels in the patient's retina. These cells have a devastating effect on the macula.

The major risk factor for AMD is age. As you grow old, your chances of suffering from this condition increase. It mostly occurs in people aged 55 years and over.
Some other risk factors are:

  • Genetics - A person with a family history of macular degeneration is likely to suffer from the condition.
  • Smoking - Smokers are at a high risk of suffering from AMD.
  • Race - Caucasians have a higher risk of developing AMD when compared to Latinos, Hispanics, and African Americans.
     

Signs & Symptoms

During the early stages, the signs below tend to go unnoticed:

  • An empty or dark area in the centre part of vision
  • Objects look distorted
  • Straight lines appear crooked or wavy
  • Loss of color vision
  • Inability to view objects clearly
     

Diagnosis

During the first phase, AMD is asymptomatic; however, there are cases where patients suffer from mild vision loss, blurred vision, visual distortion, metamorphopsia, and scotomas. Because AMD progresses gradually and its symptoms are often missed, dilated eye tests are highly recommended. This diagnosis is conducted by an eye care professional.
The Amsler grid, a checkerboard chart, is also another tool that has been utilized for checking the development of AMD.
Other tests that may be carried out include:

  • Dilated funduscopic tests
  • Visual acuity examination
  • Optical coherence tomography
  • Fundus autofluorescence
  • Ultrasonography
  • Indocyanine green angiography
     

Treatment 

Treatment for AMD is geared towards destroying the vessels responsible for cellular injury. The aim is to hinder the harmful elements from causing further damage and restoring normal vision.

Thermal laser photocoagulation is one of the most common treatment for managing ARMD. The procedure involves using laser beams to destroy the CNV. However, with this treatment, there are high levels of recurrence.
Verteporfin photodynamic therapy or PDT is another popular treatment for AMD. This treatment involves the use of both laser therapy and drugs. Some of the drugs used in this therapy include eylea, visudyne, and lucentis.
Other treatments include:

  • External beam irradiation
  • Focal radiation
  • Transpupillary thermotherapy
  • Intravitreal steroids
  • Antiangiogenic therapy
  • Verteporfin photodynamic therapy
     

Prevention/Follow Up

The main strategy for preventing macular degeneration is through diet. Research has shown that nutrients such as vitamin C and E, zinc, zeaxanthin, and lutein can reduce the likelihood of developing macular degeneration.