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  Normal vision. Courtesy NIH National Eye Institute
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  The same view with diabetic retinopathy.

Early diabetic retinopathy often does not have any symptoms. With further progression of the disease, patients may notice one or more of the following symptoms:

• Bleeding
• Blurred vision and gradual vision loss, and even blindness.
• Floaters which are dark spots in the field of vision.
• Shadows or missing areas of vision
• Difficulty seeing at nighttime
• Primary detachment of retina can present with similar symptoms.
• Fluctuating vision
• Blurry and/or distorted vision
• Double vision
• Other symptoms are related to diabetic ocular disease

As new blood vessels form at the back of the eye as a part of proliferative diabetic retinopathy (PDR), they can bleed (haemorrhage) and blur vision. The first time this happens, it may not be very severe. In most cases, it will leave just a few specks of blood, or spots, floating in a person’s visual field, though the spots often go away after a few hours.

These spots are often followed within a few days or weeks by a much greater leakage of blood, which blurs vision. In extreme cases, a person will only be able to tell light from dark in that eye.It may take the blood anywhere from a few days to months or even years to clear from the inside of the eye, and in some cases the blood will not clear. These types of large hemorrhages tend to happen more than once, often during sleep.

After the hemorrhage due to PDR, most of the symptoms occurs. The first time, it may not be very severe. In most cases, it will leave just a few specks of blood, or spots, floating in a person’s visual field, though the spots often go away after a few hours.These spots are often followed within a few days or weeks by a much greater leakage of blood, which blurs vision. In extreme cases, a person will only be able to recognize the light.

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