Patz 1954.

Methods	Quasi‐random treatment allocation, based on alternate admission basis. Allocation concealment was thus inadequate. There was no blinding of the intervention and it is unclear whether outcome assessments were blinded to treatment allocation. Attrition due to deaths or losses to follow‐up are not reported, so it is unclear whether there was complete outcome measure ascertainment. No power calculations were reported.
Participants	An unknown number of very low birthweight infants (</= 1500g) were enrolled from Jan 1951 to May 1953. 120 infants survived and had eye outcome assessments completed by 6 months age and were included in the analysis.
Interventions	Experimental group (restricted oxygen): infants received oxygen only for clinical indications, and to a maximum FiO2 of 0.4. The range of duration of oxygen in this group was 1 day ‐ 2 weeks. Once weaning was indicated, it proceeded over 1‐3 days. Control group (liberal oxygen): infants were placed in supplemental oxygen of 60‐70% for 4‐7 weeks, then weaned over one week.
Outcomes	Vascular RLF (any stage) in survivors Cicatricial RLF (severe grades) in survivors Cicatricial RLF (severe grades), BW <1000g, in survivors There are no data available, either published or unpublished, on mortality rates. The number of infants allocated to each group was not reported, hence outcome data can only be expressed in relation to the surviving infants presenting for follow‐up assessment.
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Adequate sequence generation?	High risk	Quasi‐random allocation based on alternate admission basis.
Allocation concealment?	High risk	Quasi‐random allocation based on alternate admission basis.
Blinding? All outcomes	High risk	Blinding not stated. Also, the experimental and control interventions were applied for different lengths of time, so treatment differences would have been obvious.
Incomplete outcome data addressed? All outcomes	Unclear risk	The focus of results seemed to be on qualitative histological data. The quantitative results seemed to report on all outcomes.