The leading cause of blindness in adults age 20 to 74 is diabetes. High blood sugar found in diabetes can harm the eye by causing the lens to swell and impairing your ability to see. If you are diabetic, regular eye exams are essential to prevent diabetes-related eye complications.

Basic Structure of the Eye

The eye is considered to be an organ. The white of the eye is called the sclera, it is covered by a thin mucus membrane called conjunctiva. The portion of the sclera visible at the front of the eye is known as the cornea.

Behind this structure is the colored part of the eye: the iris. The iris forms a hole in the center called the pupil. With the help of the iris, the pupil can adjust its size to regulate the amount of light that reaches the retina, the innermost lining of the eye.

The vitreous is the clear fluid that fills the space between the cornea and the lens. The lens sits behind the iris and helps light reach the retina. The retina has many nerve endings that send information to the brain through the optic nerve. The central part of the retina is called the macula and is responsible for straight and central vision.

High blood sugar can damage the lens, vitreous, retina, and optic nerve of the eye. The nerves and small blood vessels that supply oxygen and nutrients to these various structures in the eye can become swollen, weak, and clogged as a result of high blood sugar. If not detected and treated early, this damage can cause impaired vision and blindness. The most common diabetes-related eye problems are diabetic retinopathy, cataracts, and glaucoma.

Diabetic Retinopathy

Poorly controlled diabetes damages the tiny blood vessels that supply oxygen and nutrients to the retina; this is known as diabetic retinopathy. In the initial stages, microaneurysm can occur, a condition in which the blood vessels supplying the retina bulge slightly and sometimes leak blood or fluid. As the disease progresses, the macula becomes damaged and vision worsens. This condition is called maculopathy.

In the advanced stages of diabetic retinopathy, lack of oxygen from the original blood vessels causes new, weaker blood vessels to form. These fragile vessels may break, leaking blood and fluid into the vitreous and blocking vision. Weak vessels may also form in the tissue near the retina, detaching a portion of the retina from the back of the eye, which can result in blindness.

Warning signs of diabetic retina damage include the inability to see clearly, double vision, blurred vision, seeing rings or flashes of light, blank or dark spots in vision, pressure or pain in the eyes, or loss of periphery vision. Sometimes you may not experience any visible signs of diabetic retina damage, so regular exams are important. If the retina is damaged, keep your blood sugar and blood pressure under control to prevent further damage.

Cataract

A cataract is an opaque and cloudy area that develops in the normally clear lens resulting in blurred vision. Individuals with diabetes have twice the risk of developing cataracts than those without diabetes due to the persistent high blood sugar levels. When blood sugar levels fluctuate, it shocks the cell walls of the capillaries causing them to narrow and weaken. Blood flow is reduced, and the poor circulation that results increases the likelihood of damage and disease to the eyes. Diabetics may develop cataracts at a younger age than their healthy peers.

A different type of cataract, called a sugar cataract, is found only in diabetics. Sugar cataracts are most common in young adults with type 1 diabetes. Poor blood sugar control activates aldose reductase, an enzyme located in the eye that converts glucose into sorbitol. Sorbitol is a sugar that breaks down slowly in the body and can accumulate in the lens of the eye where it attracts so much water that the structure of the lens becomes damaged.

Glaucoma

Glaucoma is a condition where fluid pressure builds in the eye to the point where it causes damage to the optic nerve resulting in loss of sight. People with diabetes are twice as likely to suffer from glaucoma. Often by the time treatment is sought for glaucoma, 75 percent of the damage to the eye has already occurred. Warning signs of glaucoma include blurred vision, pain in one or both eyes, eye pressure, double vision, and seeing spots.

Diabetic retinopathy cannot be cured. However, before the retina becomes severely damaged, loss of vision can be prevented using laser surgery. Following are the some of the treatments available.

• Focal/grid laser treatment: Laser surgery used to block abnormal blood vessels from leaking blood and fluid into the eye

• Panretinal laser treatment: Laser surgery that seals leaking blood vessels over the entire retina

• Vitrectomy: A procedure that uses delicate instruments to remove blood clots, which develop in the vitreous during the late stages of diabetic retinopathy and block the passage of light

Cataracts are treatable by a common surgical procedure where the clouded lens is removed and replaced by a plastic lens.

Glaucoma in diabetes is treated by medications in the form of pills and eye drops, laser procedures, and surgery. The objective of the treatment is to decrease the pressure of the fluid in the eye. Glaucoma can be controlled but not cured. The earlier this condition is diagnosed the more successful the treatment.

To prevent eye problems due to diabetes, the most important measure is to control blood sugar levels and have eyes examined annually. This will help to identify any eye problems at an early stage and hopefully prevent a more serious condition. High blood pressure can also increase damage to the eyes. Check your blood pressure at least four times a year. Take your medications regularly as advised if your blood pressure is higher than normal.

You can stop further loss of sight and prevent deterioration by undergoing any treatments as advised, including surgery and medications. Engaging in physical activity is essential to lower blood sugar and blood pressure. Discuss with your physician how you can engage in an active lifestyle and reduce the risk of diabetes complications, including eye problems. Because smoking raises blood pressure, avoiding smoking can improve circulation and help prevent diabetes-related eye problems.

The Importance of Proper Eye Care

Persistently high blood sugar has a deteriorating effect on all body organs, and your eyes are no exception. Early detection and timely intervention can prevent loss of vision. It is essential to get regular eye examinations and to keep your blood sugar levels under control with a healthy diet and regular exercise.