Diabetic retinopathy often presents few symptoms initially. There is no pain associated with the disease, and vision may not be noticeably affected until the disease is advanced. Prior good vision is not a factor in the development of diabetic retinopathy.

Eventually, patients with diabetic retinopathy may experience blurred vision. This occurs when:

1. The macula (part of the retina that provides sharp, central vision) swells from fluid leaking from retinal blood vessels. This condition is known as macular edema.
   
   
2. New blood vessels growing on the surface of the retina (neovascularization) can bleed into the eye, which can decrease vision by blocking light entering the eye. The new vessels can also cause retinal detachments..
   
   
3. The macula can develop ischemia (lack of oxygen) from the decreased blood flow and stop functioning.

Other symptoms associated with diabetic retinopathy, especially in the later stages, include:

• Blank areas in the field of vision
• Glare when in bright light
• Dark streaks or red film that blocks vision
• Cloudy vision or blurred vision
• Difficulty reading or seeing detailed work
• Difficulty adjusting from bright light to dim light

However, many cases of diabetic retinopathy manifest no symptoms and can be detected only during an eye exam. For this reason, patients should have their eyes examined by an ophthalmologist at least once a year.