Central Retinal Vein Occlusion (CRVO) - Tomato Splash

A 70-year-old man with a 15-year history of hypertension and open-angle glaucoma presents with sudden, painless, severe vision loss (counting fingers) in the right eye. Fundoscopy reveals the classic "tomato-splash" appearance with diffuse flame and dot-blot hemorrhages across all four quadrants (marked **A** in the diagram), along with a swollen hyperaemic disc, dilated tortuous veins, and cotton-wool spots. The patient undergoes fluorescein angiography at 3 months, which reveals ≥10 disc-areas of retinal capillary non-perfusion. Which of the following is the most important complication to monitor for in the next 3 months?