A 58-year-old woman with type 1 diabetes (duration 18 years, HbA1c 10.1%) presents with sudden onset of floaters and blurred vision in the right eye for 2 days. She reports no pain or photophobia. On examination, visual acuity is 6/60 in the right eye. Dilated fundoscopy reveals extensive dot-blot and flame-shaped hemorrhages, cotton-wool spots, venous beading, and areas of retinal whitening. Critically, you observe new vessels at the disc margin and on the surface of the retina temporal to the macula. What is the most appropriate immediate management?