A 48-year-old woman from Mumbai with a 12-year history of uncontrolled hypertension (currently on no antihypertensive therapy) presents with sudden-onset headache, blurred vision, and confusion for 2 days. Blood pressure is 196/128 mmHg. Fundoscopy shows flame-shaped hemorrhages, cotton-wool spots, papilledema, and macular star exudates. Serum creatinine is 3.2 mg/dL (baseline 0.8 mg/dL), and urinalysis shows proteinuria 4+ with RBC casts. What is the most likely pathophysiological mechanism underlying the retinal findings in this patient?