My Diabetes Project – Eye complications
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To understand some vision problems that arise from diabetes, we need to know how the eye works.
The eye is a ball covered with a tough outer membrane. The covering in front is clear and curved, and the curved area is called the cornea. This focuses light while protecting the eye. After light passes through the cornea, it goes through the anterior chamber (which is filled with a protective liquid called the aqueous humor), through the pupil, a hole in the iris, the colored part of the eye and then through a lens which helps focus the light. Lastly, the light another fluid-filled chamber in the center of the eye (called the vitreous) and hits the back of the eye, the retina. It’s the retina’s job to record the images focused on it and turn those pictures into electrical signals, which the brain receives and decodes. There’s a part of the retina that is specialized for seeing fine detail called the macula. There are blood vessels in and behind the retina that nourish the macula.
- Glaucoma is caused by pressure building up in the eye, which means the aqueous humor (the protective liquid found in the anterior chamber) drains more slowly and eventually builds up in the anterior chamber. This pressure pinches the blood vessels that carry blood to the retina and optic nerve, and vision is gradually lost because the retina and nerve are damaged. People with diabetes are 40% more likely to suffer from glaucoma than those without diabetes. The longer you have diabetes, the more common glaucoma is, and risk also increases with age. There are several different treatments for glaucoma, including drugs that reduce pressure in the eye or surgery, so talk to your doctor about what would be the best option for you.
- Cataracts occur when the clear lens covering the eye becomes cloudy, blocking out light. People with diabetes are 60% more likely to develop cataracts, tend to get them at a younger age, and have them progress faster. Mild cataracts may require you to wear sunglasses more often or use glare-control lenses in your glasses. But if you have severe cataracts, doctors may remove the lens of the eye or you could get a new transplanted lens. Be aware that the removal of the lens may worsen retinopathy (see below), causing glaucoma to develop.
- Retinopathy is a general term for damage to the retina caused by diabetes inc;luding:
- Nonproliferative retinopathy—when capillaries in the back of the eye balloon and form pouches. This is the most common form of retinopathy and has three distinct stages(mild, moderate, and severe. These can develop as more blood vessels become blocked. This type does not usually require treatment.
- Macular edema—sometimes when a person has nonproliferative retinopathy, the capillary walls lose their ability to control the passage of substances between the blood and the retina. Fluids can then leak into the part of the eye where focusing occurs, called the macula. If the macula swells with fluid, the patient develops macular edema and vision blurs or is lost entirely. Treatment for macular edema tends to be effective at stopping and sometimes reverses vision loss.
- Proliferative retinopathy—a more severe form of retinopathy, that occurs when blood vessels are so damaged they simply close off and new blood vessels begin growing in the retina. The new vessels are weaker and can leak blood that blocks our vision, a condition called vitreous hemorrhage. The new vessels can also cause scar tissue to grow, and after it shrinks, the retina can be distorted or pulled out of place, causing a retinal detachment.
- Treatment can help to prevent blindness in most people and are more successful the sooner retinopathy is diagnosed.
- Scatter photocoagulation—on two or more occasions, an eye care professional makes hundreds of tiny burns on the retina to help seal blood vessels and stop them from growing and leaking. This can help reduce the risk of blindness from vitreous hemorrhage or detachment of the retina, but only works before the bleeding or detachment has progressed very far.
- Focal photocoagulation—when an eye care professional aims the laser directly at leaking blood vessels in the macula, which can’t cure blurry vision caused by macular edema but can keep it from getting worse.
- Vitrectomy—useful for when the retina has already detached or a lot of blood has leaked into the eye, this procedure can help remove scar tissue and cloudy fluid from the eye. The removal of blood from the eye is usually successful, but reattaching a retina only works about half the time.
Treatment for macular edema includes focal laser therapy to slow fluid leakage and the injection of medications into the eye that slow the growth of new blood vessels and reduce the leakage of fluid into the macula.
Risk factors for retinopathy include how well you’re able to control:
- your blood sugar
- how high your blood pressure is
- how long you’ve had diabetes, and
- your genes
The retina can be badly damaged before you notice any change in your vision, which is why it’s important to have an eye care professional examine your eyes regularly.