Macular degeneration, more appropriately named age-related macular degeneration (AMD), is a common, progressive eye disorder, affecting an estimated 11 million Americans. It’s the leading reason for vision loss — causing more than glaucoma and cataracts combined.
AMD is caused by deterioration of the central part of the retina, the light-sensing tissue at the back of the eye. This region is called the macula.
Macular degeneration doesn’t cause total blindness, because it only affects your central vision, not your peripheral vision. You see a black spot in the middle of your visual field that prevents you from reading, driving, and recognizing faces and even colors.
Retina Specialists has locations in Dallas, DeSoto, Plano, Mesquite, and Waxahachie, Texas, and our expert team of ophthalmologists specializes in retinal diseases, including macular degeneration. Our goal is to maximize your vision and improve your quality of life.
Here’s what you need to know about AMD, its causes, and its treatments.
How AMD works
If you think of the eye like a camera, the lens bends the incoming light, focusing it on the light-sensitive film (or microcircuit) inside to create a visible image. When everything’s in good working order, the macula collects the highly detailed information in the central region of the object in front of the lens and sends it to the optic nerve, which then sends the information on to the visual cortex of the brain. The brain decodes the information and registers it as an image.
When the macular cells deteriorate, they can’t record the information properly, so the clarity of the image decreases until the image eventually disappears.
There are two types of AMD: dry and wet.
1. Dry macular degeneration (atrophic)
Dry macular degeneration, which accounts for 85-90% of all cases, occurs when your macula thins and accumulates small deposits of waste products (lipids and proteins) called drusen. Drusen probably don’t cause AMD, but having them 1) increases your risk, and 2) may be an early sign that you have the disease.
Symptoms of dry AMD include:
- Reduced central vision
- Distorted straight lines (become wavy)
- Need for brighter lighting
- Blurred vision
- Difficulty recognizing faces
- Damage to the retina
Treatment is primarily composed of low vision rehabilitation.
2. Wet macular degeneration (exudative)
Only 10-15% of all AMD cases are of the wet variety, and most patients have the dry form first.
In wet macular degeneration, abnormal blood vessels grow behind the retina, leaking fluid into the macula. This damages the cells and can lead to scar tissue buildup.
Many of the symptoms are the same as the dry form, but you can also experience:
- A blurred spot in the central part of your vision
- A dark spot caused by blood vessels that bleed or leak fluid
- Rapidly worsening symptoms
Wet AMD progresses more quickly than the dry form.
In addition to low vision rehabilitation, patients with the wet form can also benefit from medications injected directly into the eye to prevent the growth of new blood vessels. The medications are called anti-vascular endothelial growth factor (anti-VEGF) drugs, which have been repurposed from their original use as a colon cancer treatment.
It’s important to note that the drugs can only prevent future deterioration; once damage has occurred to the macula, it can’t be reversed.
Causes of macular degeneration — Is it hereditary?
The specific causes of AMD aren’t well-known, in part because there hasn’t been enough research funding to tease them out. What is known is that the causes are complex, most likely including both heredity and environmental factors.
The biggest risk factor for AMD is age, as it’s most likely to show up in people 55 and older. Additional risk factors include smoking, being Causasian, or having a family history of the condition.
If your eyesight is becoming slightly blurred in the central part of your visual field, you need to come in to Retina Specialists as soon as possible for an evaluation, as early treatment can help save your sight. Give us a call at any of our offices to schedule an appointment.