First screening - carried out at 32 weeks of post menstrual age (PMA) or 4 weeks of postnatal age, whichever is later In the given scenario, baby is born at 28 week gestation, so 1st screening should be done at 4 weeks postnatal age i.e 32 weeks PMA As the baby is already 2 weeks old screening for ROP should be done 2 weeks later.