Main Symptoms of Diabetic Retinopathy
Diabetic retinopathy is typically asymptomatic in its early and moderate stages, which is precisely why systematic screening is critical—patients often have no visual complaints until irreversible damage has occurred. 1
Early Disease (Mild to Moderate Nonproliferative Retinopathy)
Patients experience no symptoms whatsoever in the early stages of diabetic retinopathy, despite the presence of microaneurysms, dot-and-blot hemorrhages, and hard exudates on examination. 2, 3
Visual field testing in eyes with mild disease (ETDRS levels 10-35) shows no evidence of field loss, with mean deviation values remaining normal in 96% of cases. 4
This asymptomatic period can persist for years, particularly in type 1 diabetes where retinopathy typically requires at least 5 years of hyperglycemia to develop. 1
Advanced Disease (Severe Nonproliferative and Proliferative Retinopathy)
When symptoms finally appear, they indicate advanced disease:
Vision loss or blurred vision occurs from vascular leakage causing macular edema or from retinal ischemia. 2, 3
Floaters or dark spots result from vitreous hemorrhage when new abnormal blood vessels rupture. 2, 3
Visual field defects become evident in moderate to severe disease (ETDRS levels 43-65), with 44% of eyes showing significantly reduced mean deviation values and 6.5% of tested points demonstrating reproducible sensitivity loss. 4
Sudden vision loss can occur from tractional retinal detachment or dense vitreous hemorrhage. 3
Diabetic Macular Edema
Central vision impairment develops when fluid accumulates in the macula, which can occur at any stage of retinopathy. 3
This is the most common cause of legal blindness in non-insulin dependent diabetics and frequently produces central vision loss. 5
Macular edema threatens visual acuity and requires prompt ophthalmologic referral regardless of the stage of background retinopathy. 1
Critical Clinical Pitfall
The absence of symptoms does not indicate absence of disease. Nearly all diabetic patients will develop some degree of retinopathy after 20 years of diabetes, and 50% of those with type 1 diabetes will have proliferative retinopathy after 15 years—most progressing silently until vision-threatening complications arise. 5
This is why the American Diabetes Association mandates screening within 5 years of type 1 diabetes diagnosis and immediately at type 2 diabetes diagnosis, regardless of whether patients report any visual complaints. 1