The optimal time for fundus screening in preterm infants is around 4 to 6 weeks of birth, but in very preterm infants, the best time to do fundus screening is around 32 to 34 weeks of corrected gestational age. The organ function of preterm infants is poorer than that of full-term infants, and the retinal blood vessels are immature, which can easily affect vision. If the screening is not timely, it will not be able to detect whether the retina is diseased in time, thus missing the best time for treatment. It is generally recommended that funduscopic screening for preterm infants be performed around 4~6 weeks of birth. Most of the preterm infants have to inhale oxygen after birth, and inhalation of high concentration of oxygen will lead to spasm of retinal blood vessels and ischemic damage to the retina, so fundus screening should be performed according to the clinical needs. Fundus screening includes checking visual acuity, checking whether there is any problem in the macular area, which can see the vascular morphology of the retina, whether there is any abnormality in the blood vessels, and whether there is any lesion in the structure of the retina itself, and so on. Preterm babies need to be cared for under the guidance of professionals due to poor organ development and resistance.