Many people are opting out of regular visits to an ophthalmologist, according to 2011 statistics from the Centers for Disease Control and Prevention. This practice has serious effects on eye health since many diseases causing blindness have no physical symptoms in their early stages and can only be identified through routine eye exams.
During an eye exam, the ophthalmologist looks at the outer features and the internal structures of the eye. One structure an ophthalmologist examines is the retina, a thin tissue lining the inside of the eye. The retina’s function is to receive light from the eye’s lens, which it then converts into signals transmitted to the brain via the optic nerve. The retina also contains a layer of light-sensitive photoreceptor cells responsible for detecting visual details such as light intensity and color. It plays a critical role in a person’s ability to see.
While not the only eye condition to cause blindness, diseases affecting the retina are known to leave patients vulnerable to losing their eyesight. Below are three of the most common retinal disorders that can lead to blindness.
1. Diabetic Retinopathy
Having diabetes can result in a number of adverse health effects on the body, including vision loss from diabetic retinopathy. The condition occurs when a person with diabetes maintains high blood sugar levels over a prolonged period, causing the delicate blood vessels sustaining the retina to become blocked. In the early stages of the disease, the blood vessels swell and weaken, leaking blood and other fluid into the retina and causing progressive damage to vision. In the advanced stages of the disease, new, abnormal blood vessels may form in the eye in an attempt to provide the retina with nutrients that cannot pass through the original blocked blood vessels. The abnormal blood vessels can leak or break in the eye, causing vision damage and even scarring. When the blood vessels scar and contract, they can eventually pull the retina away from the eye surface entirely in a condition known as retinal detachment, which can cause blindness.
This condition is one of the most common causes of blindness and visual impairment among American adults of working age. In 2010, the CDC indicated approximately 7.7 million people in the United States had diabetic retinopathy, with the number expected to climb to 14.6 million by 2050.
2. Macular Degeneration
The often age-related eye condition occurs in a central portion of the retina known as the macula. Approximately five millimeters in diameter, the macula is the part of the retina specifically responsible for visual functions such as detecting fine detail, processing color and focusing central vision. Macular degeneration can occur in a dry or wet form, with the dry form accounting for up to 90 percent of all cases of the disease. The dry form is caused by the growth of large fat and protein deposits beneath the macula, preventing oxygen from reaching the retina. The wet form occurs when blood vessels grow irregularly under the macula and can leak blood and cause retinal damage. While macular degeneration cannot be cured, it can be maintained with treatment. Untreated, it can eventually lead to a complete loss of central vision.
Macular degeneration is one of the most common causes of vision loss among older Americans, with the CDC indicating that approximately 6.5 million people over the age of 40 years old are living with the effects of the condition to some degree. Although primarily associated with older people, cases in young people also occur, such as Stargardt disease, the most common form of inherited juvenile macular degeneration.
While macular degeneration mainly occurs in older people, retinoblastoma, while rare, is a condition most often seen in juvenile patients. Retinoblastoma is a form of cancer originating in the retina. One in three cases of retinoblastoma is inherited, and is caused when a mutated RB1 gene fails to control the replication of retinal cells while a fetus is developing in utero. This leads to the development of a tumor in the retina, which can cause blindness and even death if not identified early. In the non-hereditary form, typically only one eye is affected and there is no family history of the disease. In this instance, during early childhood the RB1 gene in certain retinal cells acquire mutations and leads to the disease.
Fortunately, prompt treatment of retinoblastoma has a 90 percent cure rate. However, the medical professionals treating children with retinoblastoma are focused foremost on saving lives over saving vision. Cancer treatments to the retina can cause scarring, and the visual function of a child who has been cured of retinoblastoma will depend on the size of the tumor, as well as its position in the retina. The condition is more likely to occur in only one eye rather than both, which allows many children affected by this condition to preserve some vision if the disease is identified early.