A 62-year-old woman with a 15-year history of type 2 diabetes mellitus presents to her general practitioner with complaints of worsening vision over the past six months. She also reports intermittent tingling and numbness in her feet, which has been progressively worsening. Her diabetes has been poorly controlled, with recent HbA1c levels consistently above 9%. She has a history of hypertension and hyperlipidemia, both of which are managed with medication. On examination, her blood pressure is 140/85 mmHg, and her BMI is 32 kg/m². Fundoscopic examination reveals microaneurysms and cotton wool spots. Urinalysis shows microalbuminuria. Which of the following interventions is most likely to address the underlying pathophysiological mechanism of her visual symptoms?