Diabetic retinopathy is damage to the retina (retinopathy), specifically blood vessels in the retina, caused by complications of diabetes mellitus. Diabetic retinopathy can eventually lead to blindness if left untreated. Approximately 80% of all patients who have had diabetes for at least ten years suffer from some degree of diabetic retinopathy. The retina is the light-sensitive membrane that covers the back of the eye.
If diagnosed and treated early blindness is usually preventable. Diabetic retinopathy generally starts without any noticeable change in vision. However, an eye doctor (ophthalmologist) can detect the signs. Hence, it is important for diabetes patients to have an eye examination at least once or twice annually.
Anybody with either Diabetes Type 1 or Diabetes Type 2 can develop diabetic retinopathy. The risk is greater the longer a patient has diabetes and the less controlled his/her blood sugar is.
According to the National Institutes of Health (NIH), USA, approximately 16 million Americans have diabetes, of which half do not even know they have the condition. Unfortunately, only about half of the half who know they have diabetes receive appropriate eye care. Consequently, diabetic retinopathy is the leading cause of new blindness in American individuals aged 25 to 74 years - 8,000 new cases each year. Approximately 12% of all new cases of blindness in America are due to diabetic retinopathy.
According to the National Health Service (NHS), UK, diabetic retinopathy is the leading cause of blindness in adults under the age of 65 in the UK.
The NHS adds that an estimated 25% of individuals with Diabetes Type 1 will have some degree of diabetic retinopathy 5 years after their symptoms first develop, and 25% of those with Diabetes Type 2 who do not require insulin. For those who require insulin, approximately 40% are estimated to have some degree of diabetic retinopathy five years after the onset of symptoms (of diabetes).
Symptoms of diabetic retinopathy
A symptom is something the patient senses and describes, while a sign is something other people, such as the doctor notice. For example, drowsiness may be a symptom while dilated pupils may be a sign.
Diabetic retinopathy typically has no symptoms during the early stages. Unfortunately, when symptoms become noticeable the condition is often at an advanced stage. Sometimes the only detectable symptom is a sudden and complete loss of vision. The only way patients with diabetes can protect themselves is attend every eye examination their doctor tells them to go to.
Signs and symptoms of diabetic retinopathy may include:
- Blurred vision
- Both eyes are usually affected
- Color vision becomes impaired
- Floaters - transparent and colorless spots that float in the patient's field of vision. Sometimes they may appear as dark strings.
- Patches or streaks block the person's vision; sometimes described as empty or dark areas
- Poor night vision
- Sudden total loss of vision.
Risk factors for diabetic retinopathy
A risk factor is something which increases the likelihood of developing a condition or disease. For example, obesity significantly raises the risk of developing diabetes type 2. Therefore, obesity is a risk factor for diabetes type 2.
Anybody who has diabetes is at risk of developing diabetic retinopathy. However, there is a greater risk if the patient:
- Does not control blood sugar levels properly
- Suffers from hypertension (high blood pressure)
- Has high cholesterol
- Is pregnant
- Smokes regularly
- Has had diabetes for a long time
- Statistics in the USA indicate that Amerindians (Hispanics) and Afro-Americans with diabetes have a higher risk than other ethnic groups with diabetes (In America "Hispanics" usually means Amerindians from Latin America; while in the UK a Hispanic tends to mean a person from Spain).
On the next page we look at the causes of diabetic retinopathy and how diabetic retinopathy is diagnosed. On the final page we discuss treatments for diabetic retinopathy and complications caused by the condition.