Retinopathy of prematurity (ROP), formerly known as posterior lens fibrous hyperplasia (RLF), was first reported by Terry in 1942, when white fibrous tissue was found behind the lens of premature infants and named after it. Studies have shown that the disease is closely related to prematurity, low birth weight, and high oxygen intake, and is due to retinal neovascularization and fibrous tissue proliferation in premature infants whose retinal vasculature has not yet developed completely. Posterior lens fibrous hyperplasia is a late scarring change of severe ROP, which was officially named retinopathy of prematurity by the World Academy of Ophthalmology in 1984. In a medical-statistical sense, prematurity is inevitable. In the United States, prematurity accounts for 20% of all newborns. In our country, this statistic is 10%, because our medical conditions are a bit behind and the other half of the children die prematurely. Retinopathy of prematurity is the best time to treat the disease if it is detected when the child is 4 to 6 weeks old, and after treatment, the child’s eyes are as normal. However, only two weeks are available for treatment, so it is also known as the “window of time”, after which only 10% of treatment is possible. Once the “window of time” closes, the child falls into eternal darkness. For premature babies, the second half of the vascular development of the eye can only be completed after birth. To save their lives, oxygen must be used, but it is the very oxygen that is used to save lives that sometimes leads to the development of malformations in the blood vessels of the eye – they no longer extend towards the edges in the high concentration, prolonged oxygen environment, but instead swell in place, thicken, knot, and sometimes form hemorrhages, creating a terrible pulling force that can eventually harden and tearing the retina from the fundus of the eye. The pain of this tearing has never been, and never will be, accurately described – it is endured by babies who cannot speak – and when it occurs, babies are left crying around the clock, without water or milk, and with tears in their hearts. Most of the major damage to vision can be avoided if preterm infants are monitored for fundus, especially if the optimal treatment period of four to six weeks of life, known as the “window of time,” is captured. “Most vision can be preserved with timely treatment. The appearance of white spots in the pupil is a sign that the lesion is in an advanced stage. Retinopathy of prematurity is divided into five stages. Before stage 3, there is a chance that vision can be saved to varying degrees, while stage 4 has little hope and stage 5 is hopeless. Once the “window of time” is closed, children lose their chance to regain their sight forever. Fundus examination: It can detect retinopathy of prematurity early and reduce the chances of missing the time window! 1, the first examination time: less than 32 weeks or weight less than 2000 grams born, in the corrected gestational age 32-34 weeks first examination, more than 32 weeks born, in 4-6 weeks after birth first examination of the fundus. 2, follow-up examination: depending on the results of the 1st examination, if there is no lesion or only stage I lesion in both eyes, the examination can be repeated once every other week until the ROP regresses and the retinal vessels grow to the serrated edge. If there are stage II lesions or pre-threshold lesions or Rush lesions, they should be reexamined once a week, and if the degree of ROP decreases during the follow-up, they can be examined every 2 weeks until the lesions are completely regressed. If stage III lesions are present, they should be reviewed 2 to 3 times per week. If the threshold level is reached, condensation or laser treatment should be performed within 72 h of diagnosis.