Macular Degeneration: An Overview and Risk Factors
Age-related macular degeneration (AMD) is the leading cause of blindness in the developed world in people over 50 years old. It is estimated that among North Americans, 11 million currently have ”dry” AMD, and 1.5 million people have “wet” AMD. AMD is the deterioration of the macula, which is a small area in the center of the retina that allows us to see details. The retina, the structure of the back of the inner eye, is like a camera in that it records what we see. However, the retina is different from a general film, as it has one specific area that allows the picture to come out perfectly clear. That area is the center point of the retina which is called the macula.
Damage to the macula affects our detailed vision and reduces the clarity of objects that we look at directly. This is the vision we use to read, drive, see the television, and do detailed work such as threading a needle, sewing, or crafts.
It also reduces contrast sensitivity – our ability to see objects that are the same tone as their background – so identifying faces and seeing curbs and steps may be difficult. Our peripheral vision, the wide area that includes everything that we are not looking directly at, remains intact so individuals with age-related macular degeneration can see all around the room, for example.
Simulation of the effects of macular degeneration, with central visual field loss
Normal aging causes changes to the macula; however, it is still hypothesized that certain modifiable risk factors are associated with age-related macular degeneration (AMD). The development of this disorder is poorly understood but though to include a mix of genetic predisposition along with other risk factors.
As we age, long-term environmental exposures together produce an increased number of free radicals, which are unstable molecules. These free radicals then go on to damage the macula. This damage causes a decreased number of photoreceptors, special type of neurons in the retina, as well as deposits in the retina itself. This hypothesis leads medical professionals to believe that by reducing toxins, the risk of age-related macular degeneration can theoretically be reduced.
Controllable Risk Factors
- Smoking: Current smokers have a two-to-three times higher risk for developing age-related macular degeneration than people have who never smoked. Smoking is thought to be the number one modifiable risk factor that can worsen the progression of AMD.
- Obesity: Studies have shown that obesity increases the risk of developing AMD
- Uncontrolled hypertension: Research by the National Eye Institute indicates that persons with hypertension are 1.5 times more likely to develop wet macular degeneration than persons without hypertension.
- Diet low in leafy green vegetables and fish: The risk of AMD is known to be reduced by eating healthy food, including leafy green vegetables and fish
- Sunlight: There is not strong evidence that blue wavelengths or ultraviolet rays can cause AMD. However, there are no adverse effects from wearing UV protective glasses so some studies have suggested UV protection
The Four Risk Factors We Can’t Control
- Advanced age: Although AMD may occur earlier, studies indicate that people over age 60 are at greater risk than those in younger age groups. This risk increases more than three-fold in patients older than 75 years of age as compared to the group of patients between 65-74 years of age (Beaver Dam Eye Study)
- Race: Whites are much more likely to lose vision from age-related macular degeneration than any other racial group
- A gene variant that regulates inflammation: While not all types of macular degeneration are hereditary, certain genes have been strongly associated with a person’s risk of age-related macular degeneration, and genetic predisposition may account for half the cases of age-related macular degeneration in this country.
- Family history: Studies indicate that your chances of developing age-related macular degeneration are three to four times higher if you have a parent, child, or sibling with macular degeneration.
More about Risk Factors and Actions to Take
To decrease your risk of developing age-related macular degeneration, or to decrease the rate of progression if you already have age-related macular degeneration, here are some actions you can take:
- Don’t smoke – and if you do smoke, try to stop.
- Do eat lots of dark green leafy vegetables. These vegetables – such as kale, spinach, and collards – contain lutein, a substance that neutralizes the free radicals that will otherwise cause damage to the macula. If you are taking Coumadin and can’t eat these vegetables because of the vitamin K in them, you can take a lutein supplement.
- Do eat lots of omega-3 fatty acids, which are found in fish, fish oil, flaxseeds, and some nuts. Omega-3 fatty acids reduce inflammation.
- Do control your blood pressure and cholesterol levels.
- Do exercise regularly and keep your weight down.
Written by Lylas G. Mogk, M.D., Edited by Sefy Paulose, M.D. March, 2022
How Is Juvenile Macular Degeneration Diagnosed?
As central visual acuity declines, your child or teenager will have difficulty reading (or recognizing pictures, numbers, and letters if not yet reading), identifying faces and facial expressions, driving, and gathering all of the visual information on a television screen, computer screen, phone, or tablet. The child may notice blurriness or distorted vision, and/or a blind spot in his or her vision.
Many children also notice difficulty visually adapting in dimly lit environments after walking indoors on a sunny day.
Due to the initial, slow progression of macular degeneration, it is common for these symptoms to go unnoticed for the first few years or to receive a preliminary misdiagnosis.
Central visual acuity (clarity) will continue to decline, and the child will be taken to an ophthalmologist for examination. The doctor will detect fatty buildup under the macula (yellow deposits) and ineffective cones and will diagnose macular degeneration.
Alternatively, if a family member has a diagnosis of juvenile macular degeneration, your child’s eyes should be examined by an ophthalmologist, and you may choose to undergo genetic testing to help determine an early diagnosis. An early diagnosis enables a person with the disease to prepare for its progression.
Are There Treatments for Juvenile Macular Degeneration?
There is currently no cure or standard, proven treatment for macular degeneration. It is possible to slow the progression by protecting the eyes from sun damage with use of quality sunglasses and a brimmed hat while outdoors in the daytime.
To learn about current research advances for juvenile macular degeneration treatments, including gene therapy, stem cell therapy, and drug clinical trials, and ARVO 2016: Emerging Drug Targets Toxic Build-Up in Stargardt Disease by Foundation Fighting Blindness.
How Would You Describe the Eyesight and How Will My Child Function with It?
Before discussing the visual symptoms of macular degeneration, it is important to understand the emotional impact of the diagnosis. With the exception of Best’s disease, likely your child is past early childhood and will fear upcoming changes when he or she hears, “You are losing your central vision.” Encourage your child to identify all feelings instead of suppressing them; connect with other children or teens with macular degeneration, and seek professional counseling. There is life beyond vision loss, though it may take much grieving (occurring all over again when vision noticeably deteriorates) and time before the entire family recognizes it.
Macular degeneration manifests with increasingly poor or absent central vision in both eyes (called central scotomas) and overall decreased “sharp” vision. As the disease progresses, color perception declines.
Your child’s teacher of students with visual impairments should perform a functional vision assessment to determine how your child uses his or her vision in everyday life and a learning media assessment to determine which senses your child primarily uses to get information from the environment. These assessments, along with an orientation and mobility assessment conducted by a mobility specialist, will give the team information needed to make specific recommendations for your child to best access learning material and his or her environment.
Macular degeneration makes it difficult, to the degree relative to the severity, to identify people and facial expressions when looking head-on; to access information or read from paper, a book, the wall, a classroom blackboard, or a digital screen (when in the child’s direct line of sight and when the object is small or has little visual contrast); to work with fine details such as needle threading; to participate in sports requiring the need to respond to oncoming objects or people; and to travel safely by walking, biking, or driving a car as straight-ahead dangers will be overlooked.
The following accommodations will help your child with the abovementioned tasks.
- Learning to use peripheral vision for tasks, called “eccentric viewing.”
- Environmental adaptations such as high contrast environments, a well-lit room, high-intensity lamps, additional time to interpret what is seen, and allowing the child or teen to sit in a preferred seat, likely sitting toward the back of a room and off-center.
- Use of low vision devices such as a monocular (pocket telescope) for distance viewing.
- High-tech assistive technology such as screen-reading software or screen-magnification software for use of computer.
- Near-vision optical devices such as a stand magnifier. The enlarged image of, for instance, text, will reduce the proportion of words in the central line of sight.
- Non-optical devices such as outdoor use of sunglasses and a hat with a brim.
- Specialized glasses (prism-based or bioptic telescopic) may reduce blind spots, as explained in Glasses for Stargardts’ Disease by the International Academy of Low Vision Specialists.
- Alternative techniques for performing life skills and academic tasks, as taught by the teacher of students with visual impairments.
- Orientation and mobility (travel training) become necessary to navigate safely with the use of a cane and public transportation.
Resources for Families of Children with Macular Degeneration