Diabetic Retinopathy

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Diabetic Retinopathy

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Diabetes

There are basically 2 types of diabetes, Type 1 and Type 2.

  • Type 1 diabetes was previously referred to as juvenile-onset or insulin-dependent diabetes. It is characterized by beta-cell destruction in the pancreas and usually leads to a complete loss of the body’s ability to produce insulin, also known as absolute insulin deficiency.
  • Type 2 diabetes was previously referred to as adult-onset or noninsulin-dependent diabetes. It is characterized by the body’s resistance of insulin that is produced. There is an insulin secretory defect that leads to relatively lower amount of insulin needed to control the sugar in the blood, thereby creating a relative insulin deficiency.

What is diabetic retinopathy?

Diabetic retinopathy is a disorder of the retina that develops overtime in almost all patients with long-standing diabetes mellitus. There are undetectable problems in the retina that cause neurosensory dysfunction in patients with diabetes mellitus. It is only when the defects in the retina began to affect the small vessels that this becomes visible to the doctor. The earliest visible clinical signs of retinopathy include micro aneurysms (small out-pouching) and bleeding. The changes in these blood vessels can continue to get worse, causing decreased blood flow through the smallest vessels called the retinal capillaries causing non-perfusion. The lack of blood flow (non-perfusion) can result in more hemorrhages, vein abnormalities, and small vessel abnormalities inside of the retina called intra-retinal microvascular abnormalities (IRMA).

The later stages of diabetic retinopathy involve the complete closure of arterioles (small arteries) and venules (small veins) and the growth of new vessels on the main nerve to the eye (Optic nerve head). These blood vessels also grow on the retina, iris, and in the angle of the eye that drains fluid. The problems with these new vessels are that they do not hold the blood and fluids like the natural ones, and this causes increased leaking of the new vessels called vaso-permeability. This leaking results in retinal thickening or swelling also known as edema during the course of diabetic retinopathy.

Vision loss results mainly from swelling of the most sensitive area of the retina called the macular called macular edema. This also causes macular capillary non-perfusion which, causes loss of vison. These blood vessels can also bleed in to the large space in the middle of the eye called the vitreous cavity, resulting in a vitreous hemorrhage, which can block vision. The vessels may also cause distortion and pull on the retina leading to a tractional retinal detachment.

Diabetes is the leading cause of new blindness among working age adults between 20-74 years.

What are the stages of diabetic retinopathy?

Diabetic retinopathy has four stages:

  1. Mild non-proliferative retinopathy,
  2. Moderate non-proliferative retinopathy,
  3. Severe non-proliferative retinopathy, and
  4. Proliferative retinopathy.

These are determined by dilating the patient eyes and completing examination of the inside posterior portion of the eye, called a fundus exam. There are times when your doctor will need to perform additional test to understand the staging of your eye disease. This may include a fluorescein angiogram, which is a water based dye that  circulates through the body and leaks out of the compromising diabetic blood vessels,  or an OCT scan of the macula, also allows a very close look at individual layers of the retina to detect swelling, in order to further evaluate and classify your diabetic retinopathy.

How does diabetic retinopathy cause vision loss?

There are two main ways that elevated blood sugar levels in diabetes can cause loss of vision:

  1. New blood vessels grow that are abnormal. They are unable to maintain the fluid within the vessels walls (incompetent) and as a result they frequently leak and bleed inside the eye, resulting in blurriness, and darkening of the vision.
  2. The abnormal and incompetent blood vessels can leak into the central retina, also known as the macula, which is the source of our best vision. This leads to macula swelling also referred to as macular edema. This can cause blurriness and distortion of the vision.

Who is at risk for diabetic retinopathy?
Anyone with Type 1 or Type 2 diabetes is at risk to develop diabetic retinopathy.

The length of time a person has diabetes is a major risk factor associated with the development of diabetic retinopathy. After 5 years, about 25% of type 1 patients have retinopathy. After 10 years, nearly 60% have retinopathy, and after 15 years, approximately 80% will have retinopathy.

In type 2 diabetic patients who have been diabetic for about 10 years, 40% of those taking insulin and 24% of those not taking insulin will have retinopathy. These rates increase to as high as 84% and 53%, respectively, when the duration of diabetes has been known for 19 years. Proliferative diabetic retinopathy develops in 2% of type 2 patients who have diabetes for 5 years and in 25% of patients who have diabetes for 25 years or more.

Does diabetic retinopathy have any symptoms?
Diabetic retinopathy is usually asymptomatic, particularly in the early stages. Blurred and obscured vision may occur in the later stages, and may be due to macular swelling or from bleeding in and on the retina or inside of the eye cavity.

What are the symptoms of proliferative retinopathy if bleeding occurs?
 If bleeding occurs, this may initially be seen as black dots, or floaters in your vision. If this occurs you should alert your doctor immediately. Sometime the bleeding is self-limited and will stop on its own, but if proliferative diabetic retinopathy is left untreated it can lead to severe vision loss and even blindness. Many people benefit from laser treatment or injection before more serious bleeding occurs. This treatment in many cases can prevent the progression to bleeding.

 

How are diabetic retinopathy and macular edema detected?
We will examine your retina on an annual basis to screen for diabetic retinopathy. We will attempt to prevent the further development or progression of diabetic retinopathy.

If there is any sign of activity during the earliest disease phase, including; the presence of abnormal or leaking blood vessels, or the presence of retinal exudate. If there is an indication of this, we will recommend further evaluation with getting a fluorescein angiogram (FA) and an OCT scan. These tests are used to detect leakage from blood vessels and to determine if there is a collection of fluid in either the intra-retinal or sub-retinal space. The FA can also determine if there is retinal ischemia, which means that a part of the retina is not receiving blood flow, which may be an indication of progressive disease to come.

 

How is diabetic retinopathy treated?
There is generally no treatment indicated during the first three stages of diabetic retinopathy, unless there is swelling of the macular (macular edema). In an attempt to prevent the further development or progression of diabetic retinopathy, patients must optimize their blood sugar level, normalize their blood pressure, and make sure the cholesterol levels are normalized. Proliferative diabetic retinopathy is treated with pan-retinal-photocoagulation (PRP) or widespread scatter laser therapy. PRP works by diminishing the retina’s demand for abnormal blood vessels growth.

If bleeding in the eye is severe, some patients have to have retinal surgery to remove the blood inside the eye. Patients should be aware that with laser therapy and appropriate follow-up care, the risk of blindness can be significantly reduced. The treatment for diabetic retinopathy cannot generally return vision that has already been lost. This is why good glucose, blood pressure and cholesterol control are so important along with regular eye exams. This monitoring all leads to prevention of retinopathy, which is the key to maintaining good vision.

How is a macular edema treated?
Recent studies have indicated that Macular Edema is best treated with intra-ocular injections of anti-VEGF therapy and or concomitant focal laser therapy or a combination of both. This protocol decreases the amount of fluid in the retina. It is important to understand that focal laser therapy stabilizes vision and reduces the risk of vision loss by about 50 percent.

What is a Pars Plana Vitrectomy?
If you have a lot of bleeding within the vitreous space, which is the center area of the back of your eye, some time will be allotted to see if this will clear on its own. If this blood does not clear from the vitreous space, the doctor may recommend surgery: pars plana vitrectomy (PPV) to remove the blood and restore your vision.

During a PPV a small instrument is used to remove the vitreous gel and blood from the back of your eye, which is obscuring your vision. As the vitreous is removed it is replaced with a balanced salt solution. This procedure is usually performed in an outpatient setting with the patient going home after the surgery.

What can I do to protect my vision?

The most important thing you can do is obtain an annual comprehensive eye exam with a Retinal specialist. Screening exams are crucial in patients with Diabetes as often the disease can be asymptomatic despite the presence of retinal damage.

It is also important to:

  • Maintain a healthy lifestyle with exercise and weight control
  • Optimize blood sugar control, blood pressure, cholesterol levels
  • Optimize HgbA1c: glycosylated hemoglobin, which is a test that assesses the average plasma glucose concentration levels over an extended period of time (i.e., the previous four weeks to three months) to give you and the doctor a better idea of how well you sugar is being controlled over time.

A pivotal study, Diabetes Control and Complications Trial (DCCT), evaluated thousands of patients with diabetes. This study showed that better control of blood sugar levels delayed the development and slowed the progression of diabetic retinopathy. Other studies also showed that controlling the blood pressure and cholesterol can reduce the risk of vision loss from diabetic retinopathy.

We continue to learn the role of the pivotal players in Diabetes/Diabetic Retinopathy/Diabetic Macular Edema via new clinical advances/clinical trials and thus continue to evolve with innovative strategies to add new modalities to our treatment paradigm and strive for a cure to this vision impairing disease.

If you or a family member has diabetes please make an appointment to see us at The Florida Eye Research and Surgical Therapy Institute. We will optimize your vision, and keep close watch on any changes in your eye that might necessitate treatment.

Our goal is to help you maintain good vision your entire life.