Diabetic Retinopathy

Diabetic retinopathy is a complication of diabetes. The disease causes damage to the retina, making the eyes more sensitive to light and color, and can lead to vision loss or blindness.
Diabetic retinopathy does not show symptoms until it has progressed, so regular checkups are important. There is no cure, so diabetes treatment and blood sugar control are essential to prevent the condition from worsening.

This article describes following topics.

・How diabetes causes diabetic retinopathy
・How to test for diabetic retinopathy
・How to treat and prevent diabetic retinopathy

Diabetes is a disease in which the concentration of glucose in the blood (blood sugar level) remains high.
It is estimated that there are more than 22 million people at risk of diabetes in Japan. This includes approximately 12 million people who are “strongly suspected of having diabetes” and have been diagnosed with diabetes and are currently undergoing treatment, as well as approximately 10 million people for whom “the possibility of having diabetes cannot be denied.”
(Source: 2019 National Health and Nutrition Survey)

Diabetes itself is not a life-threatening disease, but if hyperglycemia continues, it can damage small blood vessels and cause various complications, which is a major problem.
Diabetic retinopathy is one of the “three major complications” of diabetes, along with diabetic nephropathy and diabetic neuropathy. Normally, the retina in the eye receives incoming light as a stimulus and transmits it to the optic nerve and brain. However, when the retina is damaged by diabetes, the vision deteriorates.
As diabetes worsens, the symptoms of diabetic retinopathy can progress and ultimately lead to blindness. Diabetic retinopathy, along with glaucoma and other diseases, is one of the leading causes of blindness in middle age.

When blood sugar levels remain high due to diabetes, the following processes lead to retinopathy

1. Simple retinopathy

Simple retinopathy is the earliest stage of diabetic retinopathy. First, the capillaries in the retina begin to become fragile because of persistent high blood sugar levels. Eventually, blood leaks from the capillaries and proteins and lipids in the blood begin to deposit on the retina.

2. Preproliferative retinopathy

When simple retinopathy progresses to preproliferative retinopathy, the capillaries become clogged, and oxygen and nutrients cannot reach the inside of the retina. This condition is called preproliferative retinopathy, and the capillaries begin to show irregular shapes such as expanding and tortuous. Even at the preproliferative retinopathy stage, there are no subjective symptoms unless there is an abnormality in the macula in the center of the retina.

3. Proliferative Retinopathy

In the proliferative retinopathy stage, capillaries become blocked over a wide area, causing the retina to become oxygen-deficient. To compensate for this lack of oxygen, new blood vessels are formed in the retina.
However, the new blood vessels are fragile and prone to bleeding in the vitreous. Eventually, a tissue called a proliferative membrane forms around the new blood vessels. This can pull on the retina and cause retinal detachment. This can lead to vitreous bleeding, retinal detachment, and even glaucoma, which can lead to vision loss or blindness.

Symptoms of Diabetic Retinopathy

The mild stages of diabetic retinopathy, simple retinopathy and preproliferative retinopathy do not cause any symptoms and are often only detected during regular eye examinations.
If left untreated until vision loss begins and becomes noticeable, it becomes difficult to stop the progression and the risk of blindness increases.
Therefore, regular eye examinations are important for early detection.

Patients with diabetes or “suspected” diabetes should visit an ophthalmologist once a year for an examination for retinopathy.
Because diabetic retinopathy can begin with small retinal hemorrhages, a detailed fundus examination using mydriatic drugs (eye drops that dilate the pupils) is particularly important. By performing a detailed fundus examination, the severity of the disease can be determined in the early stages, when there are no symptoms.
If retinopathy is suspected, fluorescein angiography is done to determine the extent of avascularity (areas lacking oxygen) in the retina and to see where blood vessels are leaking the contrast agent.
Optical coherence tomography (OCT) is also used to diagnose diabetic macular edema, another cause of vision loss due to diabetes. It provides a three-dimensional view of the extent of retinal swelling and retinal neovascularization and is used continuously for follow-up observation.

If a diagnosis of preproliferative, proliferative retinopathy, or diabetic macular edema is made, treatment is performed to prevent further deterioration of the retinopathy.

Retinopathy photocoagulation (laser therapy)

As retinopathy progresses, the retina becomes fragile and new blood vessels form, making it prone to bleeding. Therefore, it is important to reduce the retina’s oxygen demand and inhibit new blood vessels through laser surgery.

Retinopathy photocoagulation can also be used to treat bleeding and vitiligo, and can slow the progression of retinopathy. It can be performed on an outpatient basis using topical anesthesia, with multiple treatments lasting 15 to 30 minutes each.

Vitrectomy

If proliferative retinopathy causes vitreous hemorrhage or retinal detachment (a disease in which the retina separates from the back of the eye), a vitrectomy is necessary.

The bleeding area is sucked out with a suction cutter and the detached retina is put back in place.
*For more information on measures related to retinal detachment, please click here.

Intravitreal injection

Intravitreal injection is a treatment that prevents the growth of new blood vessels by injecting a drug called anti-VEGF antibody into the vitreous. It is also effective against diabetic macular edema and can be treated on an outpatient basis. However, it is necessary to continue using antibacterial eye drops for three days before the injection, and eye drops are also essential for several days after the injection.

It is important to control blood sugar levels in order to prevent the onset of the disease or to limit its severity if it does occur. If the disease is in the early stages of simple retinopathy, these preventive measures may improve the symptoms.

Blood sugar control

People with poor blood sugar control are more likely to develop or worsen severe retinopathy. Aggressive blood sugar lowering has been shown to lower the incidence of diabetic retinopathy compared to gradual lowering.
However, because a sudden drop in blood glucose levels may temporarily worsen diabetic retinopathy, caution is required when treating patients who already have diabetic retinopathy.
In the treatment of diabetes, it is important to check HbA1c (hemoglobin A1c), a test value that indicates the percentage of sugar bound to hemoglobin in red blood cells. People who normally have high blood sugar levels also have high HbA1c, but if you can keep HbA1c below 7%, you can prevent the onset and progression of retinopathy.

The following lifestyle modifications are effective in preventing diabetes and diabetic retinopathy.

・Regular lifestyle
・Eating three well-balanced meals
・Pay attention to the intake of alcohol, sugar and salt
・Moderate exercise

Blood pressure control

Blood pressure control is also important to protect the retina.
High blood pressure alone can cause retinal lesions, which is called hypertensive retinopathy. It has also been pointed out that high blood pressure can worsen diabetic retinopathy, and appropriate lowering of blood pressure can prevent the onset and aggravation of retinopathy.

What are the visual characteristics of diabetic retinopathy?

In cases where only diabetic retinopathy is present, there is little change in vision until the disease progresses to the intermediate stage (preproliferative retinopathy), and subjective symptoms are unlikely to appear.
When diabetic macular edema is combined with diabetic retinopathy, symptoms such as distorted vision, partial loss of vision, or blurred vision may occur.

Can diabetic retinopathy be cured?

Diabetic retinopathy is an incurable disease. In addition to treating diabetes itself, it is important to control blood sugar levels and prevent the symptoms from worsening.
Diabetic retinopathy is an incurable disease. In addition to treating diabetes itself, it is important to control blood sugar levels and prevent the symptoms from worsening.

What is the rate of blindness caused by diabetic retinopathy?

An estimated 3,000 people suffer from vision loss due to diabetic retinopathy each year, and along with glaucoma, it is the leading cause of blindness in middle age.
According to past research data, the prevalence of diabetic retinopathy in diabetic patients is 15.0~23.0%, and it has been pointed out that more than 40% of patients will develop diabetic retinopathy after 10 years of disease duration. (Source: Diabetes Network)

Since the term “rate of blindness” in the question isn’t clearly defined, it’s not appropriate to give a figure.