Understanding Geographic Atrophy (GA) - A Severe Form of Macular Degeneration

Understanding Geographic Atrophy (GA)

Geographic atrophy (GA) is an advanced form of age-related macular degeneration (AMD) that causes progressive deterioration of the retina. The macula is the part of the retina responsible for central vision, which enables activities like reading, driving, and recognizing faces.

What Happens in Geographic Atrophy

In GA, the light-sensitive cells in the macula stop working and eventually die. This leads to vision loss in the central field of vision. Over time, GA can cause blind spots or dark empty spaces to appear when looking straight ahead.

The disease progresses very gradually, often over many years. These slowly enlarging blind spots make it harder to see faces, read, drive, or perform other routine activities that require sharp central vision.

Who Gets Geographic Atrophy

GA is an advanced form of dry AMD, which is caused by aging and thinning of the tissues of the macula. It usually affects people later in life. Age-related macular degeneration is the leading cause of severe, irreversible vision loss in people over age 60.

Like other forms of macular degeneration, GA occurs more often in people with certain risk factors. These include:

• Being over 65 years old
• Having a family history of macular degeneration
• Having high blood pressure or high cholesterol
• Obesity
• Smoking

Signs and Symptoms of Geographic Atrophy

GA causes vision loss very gradually, so symptoms may not be noticeable at first. The most common early symptoms are:

Blurred Central Vision

As GA damages the central retina, it becomes more difficult to see fine details, even when using prescription glasses. Reading small print, doing detail work like sewing, or recognizing people's faces can become increasingly challenging.

Distorted Images

While looking straight ahead, objects can appear bent, warped, or watery. Straight lines like door frames or shelves may appear wavy or curved.

Dark Patches or Blotches

One of the most distinctive signs of GA is a dark, empty patch or blind spot in central vision. This happens when groups of photoreceptor cells die, causing permanent blind spots.

These patches may be gray, brown, or black in appearance. The blind spots are not obvious at first but expand and gradually merge over months and years. Multiple blind spots can occur over time.

Slowly Progressing Vision Loss

The patches of blindness tend to progress very slowly over many years. Vision loss from GA in one eye does not necessarily mean the other eye will deteriorate too. In some cases, only one eye is affected.

Without treatment, these growing blind areas can eventually destroy sharp central vision. Peripheral or side vision is generally unaffected by GA.

When to See a Doctor

It's important to have a comprehensive dilated eye exam if you experience any sudden changes in vision or notice ongoing symptoms like blurred or distorted central vision. An ophthalmologist can diagnose GA and other eye conditions.

If you are over 50 years old, get a complete medical eye exam every one to two years to screen for problems like macular degeneration, glaucoma, diabetic retinopathy, and cataracts.

Diagnosing Geographic Atrophy

To diagnose GA, an ophthalmologist will:

• Take a full medical history to identify possible risk factors
• Perform a visual acuity exam to measure vision clarity and function
• Use eye drops to dilate the pupils and get a better view inside the eye
• Examine the back of the eye with specialized imaging tests

Imaging tests like optical coherence tomography (OCT) and fundus autofluorescence can confirm thinning of retinal tissues and areas of cell death from GA. These tests also allow the doctor to monitor the rate of disease progression over time.

Getting Earlier Diagnosis and Treatment

Currently there is no cure for GA, but earlier diagnosis provides the best chance to slow vision loss before it substantially impacts quality of life. That's why regular eye exams over age 50 are so important.

In some cases, vitamins, nutritional supplements, or medications may help slow the progression of GA. Low vision devices like telescopes and magnifiers can also help maximize remaining vision.

The key is to meet with a retinal specialist at the first signs of vision impairment to help preserve sight and independence for as long as possible.

Disclaimer: This article is for informational purposes only and does not constitute medical advice. Always consult with a healthcare professional before starting any new treatment regimen.