National Eye Institute: "Facts About Diabetic Eye Disease."<br>Mayo Clinic, Patient Care & Health Information, Diseases & Conditions: "Diabetic retinopathy."<br>American Optometric Association, Glossary of Common Eye & Vision Conditions: "Diabetic Retinopathy."<br>American Academy of Ophthalmology: "What Is Macular Edema?"<br>National Eye Institute: "Facts About Macular Edema."