Final answer:
The earliest clinical sign of diabetic retinopathy is C. Microaneurysms and dot-blot hemorrhages, detected through detailed eye exams. As the condition progresses, it may lead to blurred vision, macular edema, and retinal detachment.
Step-by-step explanation:
The earliest clinical sign of diabetic retinopathy is generally considered to be C. Microaneurysms and dot-blot hemorrhages. These are small areas of balloon-like swellings in the retina's tiny blood vessels or tiny spots of blood that leak into the retina. They are often asymptomatic and can be detected only through a detailed eye examination by an ophthalmologist. As diabetic retinopathy progresses, it can lead to more severe vision problems, including blurred vision, macular edema, and potentially, retinal detachment. However, these latter signs occur in more advanced stages of the disease.
It is important for individuals with diabetes to have regular eye examinations to detect diabetic retinopathy and other ocular complications at their earliest stages. Good control of blood glucose and blood pressure is crucial in preventing or delaying the progression of diabetic retinopathy, among other diabetic complications such as diabetic nephropathy and diabetic neuropathy.