For many of us, researching our ancestral roots has become a favorite pastime. But did you know that understanding your family history can also be vital to maintaining good health?
Genetics plays a role in increasing our chances of developing many medical disorders, including those that impact vision and eye health.
More than 350 eye diseases are attributed to hereditary factors, including albinism, age-related macular degeneration (AMD), colorblindness, cataracts, glaucoma, night blindness and retinitis pigmentosa.
In adults, glaucoma and AMD are two leading causes of blindness. Glaucoma is a condition that irreversibly damages the optic nerve because of a build-up of pressure inside the eye. If left untreated, it leads to vision loss and blindness. Genetics is believed to play a major role in many forms of glaucoma. In fact, having a family member with glaucoma makes you four to nine times more likely to develop the disease.
While not all types of AMD are hereditary, an estimated 15 to 20 percent of people with age-related macular degeneration have a close relative (such as a sibling or parent) with the condition. The lifetime risk of developing late-stage macular degeneration is 50 percent for people who have a relative with macular degeneration. This is four times the risk compared to people who do not have relatives with the disease (12 percent).
A cataract is a clouding of the eye’s crystalline lens. The lens, which focuses images on the light-sensitive retina, is normally transparent. Cataracts occur when proteins in the lens form into abnormal clumps. These clumps enlarge gradually and interfere with vision by distorting or blocking the passage of light through the lens.
If you have close relatives who have had cataracts, you have a greater chance of developing them than those without a family history. Fortunately, the success rate for patients who undergo cataract surgery in the U.S. is at least 98 percent, according to the American Society of Cataract and Refractive Surgery (ASCRS). Still, it’s important to detect the condition early before it impacts vision and quality of life.
Inherited retinal diseases (IRDs) are a group of eye diseases that include retinitis pigmentosa. They can cause severe vision loss and result in blindness. Each disease is caused by one or more genes that are not working correctly. While rare, IRDs can affect individuals at any age and progress at different rates. Many are degenerative, which means that the symptoms of the disease will worsen over time.
Retinitis pigmentosa is attributed to variations in 60 genes that impact the retina. The light-sensing cells of the retina gradually die off, resulting in vision loss. As the disease progresses over time, it will eventually cause night blindness and affect peripheral (side) and central vision, which is important for reading, driving, and recognizing faces.
Researchers have identified several genes for glaucoma and are starting to find genes involved in macular degeneration. They also are making very significant progress in identifying the genes that cause retinitis pigmentosa.
Heredity also plays a role in vision problems that occur in otherwise healthy eyes. There is growing evidence that the most common vision problems among children and adults are genetically determined. The list includes strabismus (an ocular misalignment sometimes referred to as cross-eyes), amblyopia (lazy eye), and refraction errors such as myopia (nearsightedness), hyperopia (farsightedness) and astigmatism. Up to 40 percent of patients with certain types of strabismus have a family history of the disease. Researchers are working to identify the responsible genes.
Finally, it is estimated that eye abnormalities accompany one-third of inherited systemic diseases. Their presence is often the most important factor in confirming a diagnosis. For example, a dislocated lens in the eye can confirm a diagnosis of Marfan syndrome, which is associated with serious heart problems. Doctors often look for a cherry-red spot in the eye to identify Tay-Sachs disease, a progressive, fatal genetic condition that affects the nerve cells in the brain and usually strikes in infants and children.
Learning about your family’s medical history, when possible, can provide important clues about your predisposition to many eye diseases and vision problems. Family members who gather for holidays, life celebrations and reunions can easily provide the information you need if you remember to ask the right questions. Be sure to share what you learn with your eye care provider so he or she can use this information when evaluating your vision and the health of your eyes. Many eye diseases, such as glaucoma and age-related macular degeneration, have no symptoms in the early stages. Early treatment is important before these conditions become serious.
Remember, many eye diseases are passed down through generations. Take a proactive role by learning your family history and sharing it with your eye care provider. Even if you don’t have a family history of eye disease or don’t know your family history, annual eye exams are important for everyone. Early signs of eye disease and vision changes may start at any age. The AAO recommends that everyone get a baseline eye screening at age 40. Based on the results, your eye doctor will suggest to you how often to have follow-up exams.