Diabetes Mellitus and the Eyes
Diabetic retinopathy is a condition occurring in persons with diabetes, which causes progressive damage to the retina, the light sensitive lining at the back of the eye. It is a serious sight-threatening complication of diabetes.
Diabetes is a disease that interferes with the body's ability to use and store sugar, which can cause many health problems. Too much sugar in the blood can cause damage throughout the body, including the eyes. Over time, diabetes affects the circulatory system of the retina.
Diabetic retinopathy is the result of damage to the tiny blood vessels that nourish the retina. They leak blood and other fluids that cause swelling of retinal tissue and clouding of vision. The condition usually affects both eyes. The longer a person has diabetes, the more likely they will develop diabetic retinopathy. If left untreated, diabetic retinopathy can cause blindness.
Symptoms of diabetic retinopathy include:
- Seeing spots or floaters in your field of vision
- Blurred vision
- Having a dark or empty spot in the center of your vision
- Difficulty seeing well at night
Often there are no visual symptoms in the early stages of diabetic retinopathy. That is why the American Optometric Association recommends that everyone with diabetes have a comprehensive dilated eye examination once a year. Early detection and treatment can limit the potential for significant vision loss from diabetic retinopathy.
OCT and the Eyes
Optical Coherence Tomography (OCT) is a non-invasive imaging test that uses light waves to take cross-section pictures of your retina, the light-sensitive tissue lining the back of the eye.
With OCT, each of the retina’s distinctive layers can be seen, allowing your optometrist to map and measure their thickness. These measurements help with diagnosis and provide treatment guidance for glaucoma and retinal diseases, such as age-related macular degeneration and diabetic eye disease.
In addition, OCT is often used to evaluate disorders of the optic nerve. The optic nerve is made up of many nerve fibers and sends signals from your retina to your brain, where these signals are interpreted as the images you see. The OCT exam is helpful in determining changes to the fibers of the optic nerve, such as those caused by glaucoma.
Since OCT relies on light waves, it cannot be used successfully with any condition that interferes with light passing through the eye, such as dense cataracts or significant bleeding in the vitreous (the gel in the center of the eye).
Macular Degeneration and the Eyes
Also commonly referred to as, "age-related macular degeneration," this condition is diagnosed by examination of the back of the eye, which the doctor searches for a mottled appearance caused by drusen, yellow deposits that form under the retina. Optometrists typically check for macular degeneration by dilating the eyes with medicated drops and then using the slit lamp to examine the back of the eye.
Another common test that can help identify macular degeneration is the optical coherence tomography (OCT), a non-invasive imaging test that displays detailed cross-sectional images of the retina. This test identifies areas of retinal thinning, thickening, or swelling--all of which can be caused by fluid accumulations from leaking blood vessels in and under the retina.
Glaucoma is a group of eye disorders leading to progressive damage to the optic nerve, and is characterized by loss of nerve tissue resulting in loss of vision. The optic nerve is a bundle of about one million individual nerve fibers and transmits the visual signals from the eye to the brain. The most common form of glaucoma, primary open-angle glaucoma, is associated with an increase in the fluid pressure inside the eye. This increase in pressure may cause progressive damage to the optic nerve and loss of nerve fibers. Vision loss may result. Advanced glaucoma may even cause blindness. Not everyone with high eye pressure will develop glaucoma, and many people with normal eye pressure will develop glaucoma. When the pressure inside an eye is too high for that particular optic nerve, whatever that pressure measurement may be, glaucoma will develop.
Glaucoma is the second leading cause of blindness in the U.S. It most often occurs in people over age 40, although a congenital or infantile form of glaucoma exists. People with a family history of glaucoma, African Americans over the age of 40, and Hispanics over the age of 60 are at an increased risk of developing glaucoma. Other risk factors include thinner corneas, chronic eye inflammation, and using medications that increase the pressure in the eyes.
Most cataracts, a condition where the lens of the eye becomes cloudy, occurs due to age-related changes in the eyes. However, other factors can contribute to the development of cataracts, including but not limited to:
- Diabetes mellitus
- Medications and drugs
- Ultraviolet radiation
- Alcohol consumption
- Nutritional deficiency
Rarely, cataracts can be present at birth or develop shortly after. They may be inherited or develop due to an infection, i.e. rubella, in the mother during pregnancy. A cataract may also develop following an injury to the eye or surgery for another eye problem, such as glaucoma.
While there are no clinically proven approaches to preventing cataracts, simple preventive strategies include reducing exposure to sunlight through UV blocking lenses, decreasing or discontinuing smoking and increasing antioxidant vitamin intake through consumption of leafy green vegetables and nutritional supplements.
Pediatric vision screening is intended to identify children with vision disorders including amblyopia (poor vision in an otherwise normal eye), strabismus (misalignment of the eyes), significant refractive error (need for glasses) or other eye abnormalities. Vision screening can be performed in the community setting such as at health fairs, in preschools, grade schools, or can be performed in the medical home (pediatrician or family doctor’s office).
Children considered to be at risk for the development of eye and vision problems may need additional testing or more frequent re-evaluation. Factors placing an infant, toddler, or child at significant risk for visual impairment include:
- Prematurity, low birth weight, oxygen at birth, grade III or IV intraventricular hemorrhage
- Family history of retinoblastoma, congenital cataracts, or metabolic or genetic disease
- Infection of mother during pregnancy (e.g., rubella, toxoplasmosis, venereal disease, herpes, cytomegalovirus, or AIDS)
- Difficult or assisted labor, which may be associated with fetal distress or low Apgar scores
- High refractive error
- Known or suspected central nervous system dysfunction evidenced by developmental delay, cerebral palsy, dysmorphic features, seizures, or hydrocephalus