In biology class, you’ve learned that you inherit certain genes from your parents and grandparents that determine your eye color. But apart from that, have you ever wondered what other characteristics, such as astigmatism and nearsightedness have you gotten from your family? In this article, we discuss the link between genetics and various eye conditions.
When Genes Are To Blame
Refractive errors are the most common eye disorders in which the shape of the eye prevents the retina from focusing on the available light correctly. These include astigmatism, farsightedness, and nearsightedness. According to a 2013 research by Nature Genetics, in which scientists studied the date from 32 previous reports, at least 24 new genes are linked with refractive error. These are in addition to two other genes already known.
Many people suffer from eye conditions where genetics are partially to blame. In fact, there are 350 hereditary ocular diseases compiled in an extensive, highly useful database from the University of Arizona College of Medicine. Here are some of them:
- Astigmatism – British researchers studied 500 sets of twins at the Twin Research Unit at St. Thomas Hospital. They found out that heredity accounts for 50 percent of cases of astigmatism. This condition occurs when the lens inside the eye has an irregular curvature or the cornea (the clear front cover of the eye) has an uneven shape. Astigmatism causes blurry vision at any distance and can lead to eye discomfort and headaches. It frequently occurs with other vision impairments like myopia and hyperopia.
- Hyperopia – Also known as farsightedness, this condition belongs in the category of refractive error. Scientists have seen evidence that hyperopia is among the conditions determined by genetics. Common signs include difficulty maintaining a clear focus on near objects, aching eyes, fatigue, and nervousness after sustained concentration.
- Myopia – Another refractive error, myopia or nearsightedness makes farther objects appear blurred. Studies show that if neither of your parents is nearsighted, you have only about 2.5 percent chance of ending up with this eye disorder. However, if one of your parents does have it, your chance of developing myopia increases to 20 percent. Meanwhile, if both parents are nearsighted, you become 33 percent at risk, or 1 in 3.
- Color Blindness – The human eye can detect about a million colors. Those who suffer from color blindness cannot tell the differences between certain colors. This condition is primarily caused by a defective chromosome. Defects in red-green color perception are the most common type of color blindness in humans. The genes responsible for this are located on the x chromosome. Hence, color blindness affects more males than females.
- Cataracts – This eye disease develops gradually over time due to environmental factors, aging, diabetes, injury, or past surgery. Some are associated with inherited genetic disorders that put an individual at risk. Prolonged exposure to ultraviolet rays may hasten cataract development.
- Dry Eye – Environmental factors primarily cause dry eye syndrome, both in the short- and long-term. Smoking, aging, and Sjogren’s disease can also contribute symptoms. However, Nature Genetics reported in a study of nearly 4,000 sets of female twins that genes have a 30 to 40 percent impact on whether a person would develop dry eyes.
- Glaucoma – You are four to nine times more likely to get open-angle glaucoma if your family has a history with this disease than someone without that affiliation. Open-angle glaucoma is the most common kind, but other forms, such as pediatric glaucoma are usually not hereditary. They are instead caused by surgery, injury, or another condition.
- Retinitis Pigmentosa – This is a group of inherited eye disorders that affect the light-sensitive part of the retina. Retinitis pigmentosa destroys cells in the retina, causing advancing eyesight loss. Night blindness is typically the first sign of RP. As the disease progression, affected individuals develop tunnel vision and eventually loss of central vision.
- Macular Degeneration – Research reveals that your chances of developing age-related macular degeneration are three to four times higher if you have a child, parent, or sibling with the same condition. While not all types of macular degeneration are hereditary, certain genes have a strong link with a person’s risk. In fact, genetic predisposition may account for half the cases in the U.S.
- Retinoblastoma – Patients with retinoblastoma have alterations in both copies of a tumor suppressor gene that is responsible for controlling the replication of cells. Not having this suppression can leave the multiplication of retinal cells unchecked, leading to a mass of cells that constitute the tumor. This enables the cancerous tissue to grow inside the eye and even spread outside. Not all retinoblastoma cases are heritable, that’s why calculating one’s risk of handing down this disease is complex.
It’s important to note that some eye conditions are the result of what happens in your life, such as your lifestyle, overall health, and environmental elements. For example, dry eye syndrome is more common for those who live in sunny or dessert areas. In addition, the Centers for Disease Control and Prevention say that smokers are thrice more likely to develop cataracts and twice as likely to get macular degeneration than nonsmokers.
Correcting Inherited Eye Diseases
Experts from the Center for Genetic Eye Disease at the Cole Eye Institute are working closely with specialists in the Medical Genetics Program and other services at the Cleveland Clinic to find solutions for complicated eye disorders.
Early diagnosis and effective treatment are key to correcting these conditions. Your ophthalmologist, geneticist, or family doctor may refer you or your child to a clinic specializing in testing and evaluation of genetic eye disorders if they suspect the case.
The genetics of poor eyesight is too complicated to be a simple dominant or recessive trait. Every condition usually has more than one gene involved. While you may not have a say in what characteristics you inherit from your parents, you can definitely do something to correct errors in your vision. If you want to have your eyesight checked, Arizona Retinal Specialists is ready to provide topnotch vision care. Call us today at (623)474-3937 (EYES) for your questions.