Treatment Strategies for Chorioretinal Vascular Diseases: Advantages and Disadvantages of Individualised Therapy

Chorioretinal vascular diseases are among the leading causes of blindness in industrialised countries. The recent development and widespread adoption of intravitreal pharmacotherapy enables surgeons to not only stabilise disease in most cases, but also improve visual acuity (VA). Inhibitors of vascular endothelial growth factor (VEGF) have become first-line therapy for patients with neovascular age-related macular degeneration (nAMD), diabetic macular oedema (DMO), and oedema due to retinal vein occlusions (RVO). The pivotal Phase III registration studies evaluated the efficacy and safety of monthly or bimonthly injections of anti-VEGF drugs, and remain the standard against which other treatments and injection regimens are compared. Adhering to a regimen of monthly drug injections requires considerable patient compliance and allocation of substantial healthcare resources, therefore most physicians use individualised treatment strategies. As-needed (PRN) and treat and extend (T&E) regimens reduce the number of clinic visits, intravitreal injections, or both, and are less expensive than monthly therapy. Both regimens reduce unwanted macular oedema and improve VA, but compared to monthly therapy over the course of 1 year, may be 1–3 letters less effective. Trials of 5-year duration suggest that PRN treatment modulates the severity of diabetic retinopathy (DR) and stabilises vision in patients with DR. Long-term data comparing these strategies in patients with nAMD and RVO are lacking, but VA frequently declines when observation periods and treatment intervals are extended beyond 4 weeks. Current observations suggest that aggressive long-term therapy with frequent injections may produce the best VA results in patients with nAMD and RVO.