Diabetic Retinopathy

What is Diabetic Retinopathy?

Diabetic retinopathy is an eye disease due to a long history of type 1 and 2 diabetes and can cause vision loss, blindness, or even be life-threatening if left untreated.

Diabetic retinopathy is a serious eye complication that mainly affects the blood vessels of the retina.

People with prolonged diabetes mellitus, uncontrolled diabetes, or high blood sugar levels are mainly affected by this disease. The high levels of sugar in the blood can damage or choke the blood vessels of the retina causing them to swell, bleed, leak fluid, or even result in the growth of new blood vessels.

The retina is a very sensitive area in the eye and diabetes retinopathy can cause serious damage to this area or even cause blindness. Vision loss or blindness is one of the most common side effects of diabetes.

Causes

Diabetic retinopathy is caused due to the damage of the blood vessels in the retina of the eye. This can cause temporary vision loss or even blindness. Prime causes for diabetic retinopathy are:

• The macula is located in the middle of the retina and is responsible for detecting light and helping the brain interpret images. Leakage of fluid from the blood vessels in the retina can seep into the macular region and cause blurred vision.

• The blockage of blood vessels disrupts blood circulation in the eye. To improve blood circulation, new blood vessels grow in the area surrounding the retina. These blood vessels may grow abnormally and are weak. They may cause leakage of blood that may block the vision in the eye.
• The growth of new blood vessels results in the accumulation of scar tissue. This may cause excess pressure in the retina causing it to detach or tear.
• Blocked blood vessels can cause cataracts or glaucoma that may result in a loss of vision.

Symptoms

The early stages of diabetic retinopathy usually do not have any symptoms so it is hard to detect the disease. However, as the disease progresses, you may experience the following symptoms:

• Dark spots or floating dark strings.
• Blurry vision.
• Difficulty in identifying colors.
• Vision loss.
• Difficulty in vision especially at night.
• Empty patches on the eye block the vision.

Symptoms may affect both eyes.

Types of Diabetic Retinopathy

Nonproliferative Diabetic Retinopathy or NPDR

Nonproliferative diabetic retinopathy or NPDR can be mild to severe. This occurs usually during the early stages of the disease when there is no growth of new blood vessels in the eye. During this time, microaneurysms of tiny bulges can occur on the walls of the eye that may protrude into the eye. This may cause leakage of fluid and blood that may seep into the center of the retina and even the macula region causing blurred vision or swelling.

NPDR may cause dilation or even change the size of the retina causing irregular vision or loss of vision. The swelling of the macular nerves may cause macular edema which may require further investigation.

Proliferative Diabetic Retinopathy or PDR

Proliferative diabetic retinopathy occurs during the advanced stage of diabetic retinopathy. It is a more progressive and severe form of diabetic retinopathy and occurs when there is a growth of new or abnormal blood vessels in the center of the eye or retina.

This may cause leakage of blood in the eye or the formation of scar tissue that may cause a rupture in the retina of the eye. The new blood vessels grow abnormally and may put pressure on the eye causing damage to the optic nerves causing eye conditions like glaucoma or loss of vision.

Who is at risk of developing the disease?

Anyone who has long-term diabetes can develop the disease. However, you are at a greater risk of developing diabetic retinopathy if you have the following conditions:

• Uncontrollably high blood sugar.
• High cholesterol.
• High blood pressure.
• A chain smoker.
• Long-term diabetes.
• Pregnancy.
• Regular use of tobacco.

Diagnosis

If you had diabetes for a long time, it is recommended that you go for an eye exam at least twice a year to detect the disease.

It is believed that individuals who had diabetes for more than 30 years may develop diabetic retinopathy at some point in their life.

Here are a few methods that your doctor may use to detect diabetic retinopathy:

The Dilated Eye Exam

A dilated eye exam is one of the best ways to examine your eyes for detecting diabetic retinopathy. During this exam, the doctor will put some drops in the eye of the patient to dilate the pupils. The doctor then takes photographs of the eye to detect:

• Abnormal growth of blood vessels.
• Any abnormality in the optic nerve, blood vessels, or the retina.
• Increase in eye pressure.
• Loss of vision.
• Scar tissue.
• Tear or detachment of the retina.
• Swelling in the retina.
• Any blockage of the blood vessels.
• Changes in the lens of the eyes.
• Leakage of blood or fluid.
• Nerve tissue damage.

Risks

• The drops may cause a stinging sensation and the patient may feel uncomfortable during the exam.
• While taking photographs during the examination, the patient may get startled.
• The drops may increase ocular pressure.

Fluorescein Angiography

In Fluorescein angiography, doctors use a dye called fluorescein to detect the abnormalities of the eye.

The doctor injects the dye into the patient’s arm. The dye then moves into the eye and circulates. The doctor then takes the photographs. The dye will stain the abnormal blood vessels or leak into the eye. The test helps to detect:

• Leakage of blood vessels.
• Blockage of blood vessels.
• Abnormal growth of the blood vessels.

Based on the results of the fluorescein angiography, the doctor can do further tests or laser treatment. The dye will pass out of your body within 24 hours through urination. Your urine may turn dark orange due to the presence of the dye, but there is nothing to worry about. It is completely normal.

Optical Coherence Tomography or OCT

Optical Coherence Tomography or OCT provides additional information about the retina and its surrounding areas that might be useful in detecting the condition. OCT can detect the thickness of the retina and also other changes of the optic nerves.

Treatment

Treatment depends on the stage and progression of the disease. In case you have early diabetic retinopathy, the goal is to control the disease and slow the process of degeneration of the eye. Doctors will advise diet control and control of the blood sugar levels to minimize the progression of the disease.

In the advanced stage of diabetic retinopathy, the aim is to stop the formation of abnormal blood vessels that will slow down the leakage of blood and fluid into the retina.

Laser beam treatment of photocoagulation is used to seal the leaks and prevent leakage into the retina.

Photocoagulation surgery is mainly of three types:

• Scatter photocoagulation where the laser beam burns and seals the tiny holes that have formed in the retina.
• Focal photocoagulation tries to seal the vessels that are oozing blood or fluid in the macula region of the eye. This is usually done to prevent macular edema. Patients undergoing this surgery may experience blurry vision for a day and small spots initially but it will go away after some time.
• This is done to remove the fluid or the scar tissue that has formed in the eye. After vitrectomy surgery, the patient will wear an eye patch for some time. Recovery of normal vision may take a few weeks or even months.

Injections are also used to treat diabetic retinopathy. VEGF is a protein that may result in swelling of the macular or leakage from blood vessels. Anti-VEGF drugs like Avastin, Lucentis, Eylea can be administered to control the condition. The injections are generally given once a month. The treatment may continue for 3 months, but some patients may require more injections depending on the severity and progression of the disease.

Corticosteroid implants are also used for treating the disease. Corticosteroids are known to reduce macular degeneration. Doctors may implant a corticosteroid device into the eye which will release the medicine in regular dosages. However, some patients have also complained about certain side effects.

Risk factors of corticosteroids include the development of glaucoma or cataracts.

Complications

Some common complications of diabetic retinopathy are listed below:

Vitreous hemorrhage 

Vitreous hemorrhage occurs when the new blood vessels leak into the center of the retina. Initially, you can see floaters or small dark spots but as the bleeding progresses, you can lose your vision completely. However, your vision may return after a few weeks or months.

The Detachment of the Retina

Due to the abnormal growth of new blood vessels, scar tissue can occur which may put pressure on the retina causing a tear or detachment. Retinal detachment can cause vision loss. People may also experience seeing light flashes or spots or floaters in the eyes.

Glaucoma

The abnormal blood vessels can restrict the flow of fluid in the eye and also put excessive pressure resulting in the formation of glaucoma. These nerve tissues can be damaged and cause an obstruction in vision.

Complete Blindness

Retinal detachment, glaucoma, and obstruction of blood vessels can cause complete loss of vision.

Diabetic Retinopathy during Pregnancy

The severity of diabetic retinopathy can increase during pregnancy. It has been noticed that pregnant women with mild-to-moderate diabetic retinopathy have more chances to develop a more severe form of the disease.

Even pregnant women with long-term diabetes, but no history of retinopathy have developed the disease during the second trimester of pregnancy. Since the progression of the disease is fast, once diagnosed, patients should immediately go for laser photocoagulation therapy mostly for severe cases of Nonproliferative diabetic retinopathy. The patient might require multiple sittings of the therapy.

Pregnant women going through laser treatment should inform their doctor about their pregnancy. Doctors may administer fewer drops for the dilation of the pupil. However, it must be noted that the drops are completely safe and there are hardly any side effects.

Patients whose blood sugar levels are under control and with no history of retinopathy are advised to go for eye screenings at least thrice a month. They should consult their diabetologist and strictly follow their diet regime. The dietary regime completely prohibits smoking and drinking alcohol.

Women with retinopathy who are planning to get pregnant are advised to delay their pregnancy and go for ocular treatment to prevent complications.

Prevention

Prevention of diabetic retinopathy involves maintaining a healthy diet, management of blood sugar levels, and doing regular eye checkups.

Here are a few ways through which you can manage the disease:

• Maintaining a healthy diet.
• Regular checkups of blood sugar levels.
• Maintain healthy cholesterol and blood pressure level to prevent heart ailments.
• Quit smoking.
• Reduce alcohol intake.
• Exercise regularly.
• Control body weight.
• Test urine to check ketone levels.
• Do a yearly dilated eye exam.
• Inform your doctor if you experience any vision changes.

References