Macular Degeneration

Dry macular degeneration

Dry macular degeneration is a common eye disorder among people over 65. It causes blurred or reduced central vision, due to thinning of the macula. The macula is the part of the retina responsible for clear vision in your direct line of sight.

Dry macular degeneration may first develop in one eye and then affect both. Over time your vision worsens, which may affect your ability to do things such as read, drive and recognize faces. But this doesn’t mean you’ll lose all of your sight.

Early detection and self-care measures may delay vision loss due to dry macular degeneration.

Symptoms

Dry macular degeneration symptoms usually develop gradually and without pain. They may include:

  • Visual distortions, such as straight lines seeming bent
  • Reduced central vision in one or both eyes
  • The need for brighter light when reading or doing close work
  • Increased difficulty adapting to low light levels, such as when entering a dimly lit restaurant
  • Increased blurriness of printed words
  • Decreased intensity or brightness of colours
  • Difficulty recognizing faces
Macular degeneration

Dry macular degeneration usually affects both eyes. If only one eye is affected, you may not notice any changes in your vision because your good eye may compensate for the weak eye. And the condition doesn’t affect side (peripheral) vision, so it rarely causes total blindness.

Dry macular degeneration is one of two types of age-related macular degeneration. It can progress to wet (neovascular) macular degeneration, which is characterized by blood vessels that grow under the retina and leak. The dry type is more common, but it usually progresses slowly (over years). The wet type is more likely to cause a relatively sudden change in vision resulting in serious vision loss.

When to see a specialist

See your eye doctor if:

  • You notice changes in your central vision
  • Your ability to see colours and fine detail becomes impaired

These changes may be the first indication of macular degeneration, particularly if you’re over age 50.

Causes

No one knows exactly what causes dry macular degeneration. But research indicates it may be related to a combination of hereditary and environmental factors, including smoking and diet.

The condition develops as the eye ages. Dry macular degeneration affects the macula — an area of the retina that’s responsible for clear vision in your direct line of sight. Over time tissue in your macula may thin and break down.

Risk factors

Factors that may increase your risk of macular degeneration include:

  • Age. This disease is most common in people over 65
  • Family history and genetics. This disease has a hereditary component. Researchers have identified several genes that are related to developing the condition
  • Race. Macular degeneration is more common in whites than it is in other people
  • Smoking. Smoking cigarettes or being regularly exposed to smoke significantly increases your risk of macular degeneration
  • Obesity. Research indicates that being obese may increase your chance that early or intermediate macular degeneration will progress to the more severe form of the disease
  • Cardiovascular disease. If you have had diseases that affected your heart and blood vessels, you may be at higher risk of macular degeneration

Complications

People whose dry macular degeneration has progressed to central vision loss may experience depression or visual hallucinations. And dry macular degeneration may progress to wet macular degeneration, which can cause rapid vision loss if left untreated

Wet macular degeneration

Wet macular degeneration is a chronic eye disease that causes blurred vision or a blind spot in your visual field. It’s generally caused by abnormal blood vessels that leak fluid or blood into the macula. The macula is in the part of the retina responsible for central vision.

Wet macular degeneration is one of two types of age-related macular degeneration. The other type — dry macular degeneration — is more common and less severe. The wet type always begins as the dry type.

Early detection and treatment of wet macular degeneration may help reduce vision loss and, in some instances, recover vision.

Symptoms

Wet macular degeneration symptoms usually appear suddenly and worsen rapidly. They may include:

  • Visual distortions, such as straight lines seeming bent
  • Reduced central vision in one or both eyes
  • Decreased intensity or brightness of colours
  • A well-defined blurry spot or blind spot in your field of vision
  • A general haziness in your overall vision
  • Abrupt onset and rapid worsening of symptoms

Macular degeneration doesn’t affect side (peripheral) vision, so it rarely causes total blindness.

When to see a specialist

See your eye doctor if:

  • You notice changes in your central vision
  • Your ability to see colours and fine detail becomes impaired

These changes may be the first indication of macular degeneration, particularly if you’re older than age 50.

Causes

No one knows the exact cause of wet macular degeneration, but it develops in people who have had dry macular degeneration. Of all people with age-related macular degeneration, about 10 percent have the wet form.

Wet macular degeneration can develop in different ways:

  • Vision loss caused by abnormal blood vessel growth. Sometimes abnormal new blood vessels grow from the choroid under and into the macula (choroidal neovascularization). The choroid is the layer of blood vessels between the retina and the outer, firm coat of the eye (sclera). These abnormal blood vessels may leak fluid or blood, interfering with the retina’s function
  • Vision loss caused by fluid build -up in the back of the eye. When fluid leaks from the choroid, it can collect between the choroid and a thin cell layer called the retinal pigment epithelium. This may cause a bump in the macula, resulting in vision loss

Risk factors

Factors that may increase your risk of macular degeneration include:

  • Age. This disease is most common in people over 65
  • Family history. This disease has a hereditary component. Researchers have identified several genes related to developing the condition
  • Smoking. Smoking cigarettes or being regularly exposed to smoke significantly increases your risk of macular degeneration
  • Obesity. Research indicates that being obese increases the chance that early or intermediate macular degeneration will progress to a more severe form of the disease
  • Cardiovascular disease. If you have diseases that affect your heart and blood vessels, you may be at higher risk of macular degeneration

Complications

People whose wet macular degeneration has progressed to central vision loss may experience depression or visual hallucinations.

Diagnosis

Diagnosis can be made by optical coherence tomography (OCT). This non-invasive imaging test displays detailed cross-sections of the retina. It identifies areas of thinning, thickening or swelling. This test is also used to help monitor how the retina responds to macular degeneration treatments.