Diabetes can significantly affect your eyesight and the health of your eyes. According to the World Health Organization, diabetes is one of the leading causes of blindness and visual impairment among adults around the world. The National Eye Institute (NEI), part of the National Institutes of Health, states diabetes often leads to or exacerbates retinopathy, macular edema, glaucoma and cataracts. The American Diabetes Association also cautions that a number of other vision problems can occur in people with diabetes.

Diabetes can produce adverse effects on multiple parts of the eye, including the retina, lens, macula and optic nerve. Every type of diabetes-related eye disease has the potential to result in loss of vision or blindness.

Diabetic retinopathy is a major risk.

People with both Type 1 and Type 2 diabetes are at risk of developing diabetic retinopathy, as are pregnant women who develop gestational diabetes. While senior adults are at far greater risk of developing age-related macular degeneration, diabetic retinopathy is the most common cause of vision loss among working-age adults.

In people with diabetic retinopathy, the high blood sugar levels that are characteristic of diabetes tend to damage the small blood vessels in the retina. This causes the retina’s blood vessels to leak fluids and even to bleed, leading to distorted vision. In the severest cases, abnormal blood vessels form and spread over the retina’s surface, a situation that can result in the loss of cells and even scarring. This makes diabetic retinopathy the most frequently encountered cause of blindness among people with diabetes. However, the prompt diagnosis and treatment of the condition can reduce the chance of blindness by more than 90 percent.

Diabetic macular edema is a related danger.

Diabetic macular edema (DME) is a byproduct of diabetic retinopathy. In DME, fluid accumulates in the macula — a tiny point at the center of the retina that enables sharp, clear vision — and causes it to swell. This swelling can affect the highly sensitive bundle of cells, called the fovea, at the macula’s center. The loss of vision resulting from DME can worsen over a span of months, leaving a patient unable to focus properly.

According to the advocacy organization Prevent Blindness, as many as 10 percent of people with diabetes will develop DME. People with both Type 1 and Type 2 diabetes are subject to developing DME.

Floating spots are a common symptom in retinopathy and DME.

It is important to remember the beginning stages of diabetic retinopathy may be asymptomatic. However, the NEI notes a symptom commonly associated with both diabetic retinopathy and DME: the appearance of "floating" dots that are the result of blood loss from the abnormal blood vessels associated with the disease. While these often clear up over time, immediate treatment is essential in preventing the subsequent bleeding that can lead to permanent blindness. If DME occurs in association with retinopathy, the patient’s vision can become significantly blurred.

Adults of all ages with diabetes are at risk of cataracts.

Adults who have diabetes are about 60 percent more likely to develop cataracts, a clouding of the lens, than are non-diabetics. And when individuals with diabetes develop cataracts, they tend to do so at younger ages than their non-diabetic counterparts.

Glaucoma stems from increased intraocular pressure.

Glaucoma is a group of discrete ophthalmological diseases that damage the optic nerve. Many forms of glaucoma are associated with increased intraocular pressure.

The Glaucoma Research Foundation points out that diabetic individuals are two times as likely to develop glaucoma as people without diabetes. The foundation adds that a rare and difficult-to-treat kind of glaucoma, neovascular glaucoma, correlates strongly with diabetes.

Pregnant women with diabetes should get a complete eye exam.

The NEI recommends pregnant women who have diabetes to obtain a full exam with an eye care professional as early as possible in their pregnancy. These women may require more examinations as their pregnancy progresses as well.

The risk is worrisome, but science makes major diseases controllable.

Advances over the past 10 to 20 years have made the routine assessment of diabetic retinopathy and DME far simpler and more precise. In addition, advances in medicine have improved diabetes care and have given patients greater control over the disease, which is key to protecting the patient’s vision. For example, the major study Diabetes Control and Complications Trial (DCCT), showed that proper management of blood sugar levels can delay the onset of diabetic retinopathy and slow its progress.

Preventive care and early treatment can help.

The early diagnosis and treatment of eye diseases related to diabetes is the most significant factor in guarding against decreased vision and blindness.

The NEI follows standard ophthalmological protocol by stating that bringing diabetes under control is vital to prevent vision loss. Patients with diabetes should take their prescription medications as directed and adhere to the diet, exercise and other regimens recommended by their physicians. Diabetic patients who can keep their blood sugar levels — and their blood pressure — in check can reduce their risk of developing serious eye diseases.

Many people do not realize they are experiencing one of the eye conditions associated with diabetes until significant vision loss has taken place. That’s why it’s critical for people with diabetes to receive thorough ophthalmological examinations, under dilation, at least annually.