*4.3.5 Hypertension*

Hypertension is a main secondary risk factor associated with DR. Silva et al. [30] in 2007 found an increased expression of VEGF and ICAM-1 in an experimental model in rats who were in a prehypertensive or hypertensive group. They concluded that hypertension led to an increased inflammatory response in the diabetic retina and consequently worsened retinopathy.
