Medical Versus Surgical Management of Proliferative Diabetic Retinopathy: A Review of Current Treatments, Efficacy, Cost-effectiveness, and Compliance-related Outcomes

Abstract

outcomes, potential complications, the necessity of additional treatments, cost-effectiveness, and quality of life considerations. ' Treatment OutcomesThe Diabetic Retinopathy Study (DRS) established PRP as the standard of care for the treatment of PDR. 2 The DRS and the Early Treatment Diabetic Retinopathy Study (ETDRS) demonstrated a ∼50% reduction in the rate of severe vision loss (defined as 5/200 vision or worse at 2 or more consecutive 4-mo follow-up visits) in PDR for patients who received PRP. 3,4 However, despite these successes, 5% of patients ultimately develop complications requiring PPV even after full PRP treatment. 5,6 Among patients in the Diabetic Retinopathy Clinic Research Network (DRCR) Protocol S study, 45% of PRP-treated eyes required additional PRP over 2 years of follow-up, and 19% required PPV over 5 years of follow-up. 7,8 Khan et al 9 reported that over 10 years of followup, 89% of treated eyes required additional PRP, one-third required retinal surgery, and 16% required intravitreal anti-VEGF treatment. It is clear from this data that although PRP provides relatively good outcomes in the short term and medium term, over a long-enough follow-up period, the majority of patients treated with PRP ultimately do require additional interventions. This risk is further magnified in eyes with PDR with associated hemorrhage or traction, in whom rates of required PPV within 1 to 2 years were higher than in patients with uncomplicated PDR alone. 10 PRP treatment is also associated with peripheral visual field loss, declines in contrast sensitivity, exacerbations in diabetic macular edema (DME), and pain. 7,[11][12][13] Fong et al 14 reported that of patients treated with PRP, up to 50% had some degree of visual field abnormality, 38% had worsened color vision, 38% reported worsened night driving, and 60% had worsened dark adaptation. It is worth noting, however, that the initial trials involved specific laser settings, which may not reflect how laser is conducted in current clinical practice.Intravitreal injection of anti-VEGF agents has become an increasingly popular alternative to or adjuvant for PRP. DRCR Protocol S demonstrated the noninferiority of intravitreal ranibizumab to PRP for the treatment of PDR in both the 2-and 5-year analyses. 7,8 Furthermore, the ranibizumab group had lower rates of development of vision-threatening DME and had less visual field loss than the PRP group. 8 In eyes without baseline DME, the 5-year cumulative probability of developing visionthreatening DME was 22% in the ranibizumab group and 38% in the PRP group, and the rate of retinal detachment at 5 years was 7% in the ranibizumab group versus 18% in the PRP group. PPV was performed in 15% and 22% of eyes in the ranibizumab and PRP groups respectively. Rates of development of iris neovascularization and neovascular glaucoma 4 ' Engelhard et al