Data collected from inpatient and outpatient medical records
| First and last names |
| Medical record number |
| Birth date |
| Birth weight |
| Sex |
| State of parental residence |
| Postmenstrual age |
| Discharge date |
| Supplemental oxygen use |
| Presence of inpatient retinal examination |
| Presence of outpatient retinal examination |
| Date of each retinal examination |
| Results of each retinal examination including highest stage and lowest zone of each eye |