Here is the design of a clinical trial:

Official Title: Micro-invasive Pars-plana Vitrectomy vs Panretinal Photocoagulation for Severe Non-Proliferative Diabetic Retinopathy A Randomized Clinical Trial

Included conditions:
- Non Proliferative Diabetic Retinopathy

Study Armgroups:
- {'label': 'Group A', 'type': 'EXPERIMENTAL', 'description': 'Prompt panretinal photocoagulation', 'interventionNames': ['Procedure: Prompt panretinal photocoagulation']}
- {'label': 'Group B', 'type': 'EXPERIMENTAL', 'description': 'Micro-invasive Pars-plana vitrectomy', 'interventionNames': ['Procedure: 25G Pars-plana vitrectomy']}

Interventions:
- {'type': 'PROCEDURE', 'name': 'Prompt panretinal photocoagulation', 'description': 'Study eyes that receive panretinal photocoagulation (prompt PRP eyes at baseline) should have 1200 to1600 burns with a spot size on the retina of approximately 500 microns given over 1 to 3 sittings and completed within 4 weeks of initiation', 'armGroupLabels': ['Group A']}
- {'type': 'PROCEDURE', 'name': '25G Pars-plana vitrectomy', 'description': 'Study eyes that receive standard 25G Pars-plana vitrectomy that remove all the vitreous, without laser or Silicone oil tamponade, but filled with perfusion fluid. Surgery should be completed within 4 weeks after randomization.', 'armGroupLabels': ['Group B']}

Primary Outcomes:
- {'measure': 'progression rate of severe non proliferative diabetic retinopathy', 'description': 'the number of patients with severe non proliferative diabetic retinopathy progressed to proliferative diabetic retinopathy in each group from the baseline to 12 months', 'timeFrame': '12 months'}

Please estimate the sample size based on the assumption: 
The study aims for 90% statistical power at a two-sided significance level of 0.05, with an allowance for 20% loss to 1-year follow-up.
Sample size
        The sample size estimate has been computed for the primary study objective, to determine whether disease progression rate in the PPV group is superior to that in the PRP group at 1 year. The sample size calculations are based on the published Diabetic Retinopathy Clinical Research Network clinical trials.9 23 Disease progression is defined as the transition from sNPDR to PDR according to the international definition of DR.6 It is assumed that the 1 year cumulative sNPDR progression rate after the PRP treatment would be approximately 40%, and that after the PPV treatment would be 20%. By using a balanced design, 109 participants per study group will be required to achieve 90% statistical power at a two-sided significance level of 0.05. Thus, allowing for 20% of participants loss to 1-year follow-up, 272 participants are required for this study.