Here is the design of a clinical trial:

Official Title: Oral Propranolol for Prevention of Threshold Retinopathy of Prematurity

Included conditions:
- Retinopathy of Prematurity

Study Armgroups:
- {'label': 'Propranolol', 'type': 'EXPERIMENTAL', 'description': 'Oral propranolol (1.6 mg propranolol-HCl/kg/d in 3-4 divided dosages) given for a maximum of 10 weeks (depending on postmenstrual gestational age at birth)', 'interventionNames': ['Drug: Propranolol']}
- {'label': 'Placebo', 'type': 'PLACEBO_COMPARATOR', 'description': 'Placebo (same duration as oral propranolol solution)', 'interventionNames': ['Drug: Placebo']}

Interventions:
- {'type': 'DRUG', 'name': 'Propranolol', 'description': 'Oral propranolol (1.6 mg propranolol-hydrochloride/kg/d in 4 divided dosages)', 'armGroupLabels': ['Propranolol']}
- {'type': 'DRUG', 'name': 'Placebo', 'description': 'Oral solution containing the same excipients as propranolol solution', 'armGroupLabels': ['Placebo']}

Primary Outcomes:
- {'measure': 'Survival without adverse ophthalmological outcome (stage ≥ 3, AP-ROP, or any ROP treatment)', 'description': 'The primary endpoint for efficacy is survival until 48 weeks postmenstrual age without adverse ophthalmological outcome (stage ≥ 3, AP-ROP, or any ROP treatment) diagnosed according to the International Committee for the Classification of Retinopathy of Prematurity Revisited.', 'timeFrame': '48 weeks postmenstrual age'}

Please estimate the sample size based on the assumption: 
80% power at a two-sided alpha level of 5%, with an anticipated loss to follow-up of 5%, 10% of eligible patients not recruited due to lack of parental consent, and 3% excluded for medical or organisational reasons.
Sample size calculation
        The ROPROP study is designed to demonstrate the superiority of oral propranolol in comparison with placebo in increasing the rate of infants surviving to 48 weeks postmenstrual age without threshold ROP (primary endpoint). Assuming a rate of 30% of infants who will progress to threshold ROP or die,21 262 infants (131 in each group) will have to be analysed to have 80% power (at a two-sided alpha level of 5%) to detect a 50% lower risk in the treatment group (two-sided Fisherâs exact test-based calculations, G*power 3.1.9.2, 2014).22 With an anticipated loss to follow-up of 5% (withdrawal or other reasons), the total number of infants allocated to treatment will be 276. Assuming that 10% of eligible patients will not be recruited for lack of parental consent and 3% for medical or organisational exclusion criteria, a total of 312 patients will be assessed for eligibility. This translates to 624 patients screened by funduscopy, assuming a rate of incipient ROP of 50%, and 718 infants below 28 weeksâ gestational age admitted to neonatal care, assuming an early mortality rate of 15%.