I. Clinical signs 1. The site of ROP is divided into 3 zones: zone 1 is centered on the optic disc, and the distance from the center of the optic disc to the central macular concavity is drawn as a circle with a radius of 2 times; zone 2 is centered on the optic disc, and the radius from the center of the optic disc to the nasal serrated edge is drawn as a circle; the remaining part outside zone 2 is zone 3. The more backward the early lesion, the greater the risk of progression. 2, the severity of the lesion is divided into 5 stages: stage 1 occurs at approximately 34 weeks of corrected fetal age, and a demarcation line appears between the vascular and non-vascular areas in the temporal periphery of the fundus retina; stage 2 occurs at an average of 35 weeks (32-40 weeks), and the fundus demarcation line is elevated with ridge-like changes; stage 3 occurs at an average of 36 weeks (32-43 weeks), and retinal vasodilatation and proliferation occurs on the ridge of the fundus demarcation line, accompanied by The pre-threshold lesion occurs at an average of 36 weeks, and the threshold lesion occurs at an average of 37 weeks; stage 4 has tractional retinal detachment due to fibrovascular proliferation, starting at the periphery and gradually progressing to the posterior pole; this stage is divided into A and B according to the presence or absence of macular detachment, A without macular detachment; B with macular detachment; stage 5 has total retinal detachment (approximately 10 weeks after birth). “Plus” disease refers to dilated and tortuous retinal vessels in the posterior pole, and a “+” is written next to the stage of the lesion in the presence of “Plus” disease, e.g., stage 3 +. “Pre-threshold ROP” indicates that the lesion will progress rapidly, requiring a shorter review interval and close observation of the disease, including: any lesion in zone 1, stage 2+ in zone 2, stage 3, stage 3+. Threshold lesions include: stage 3+ adjacent lesions in zone 1 and zone 2 up to 5 clock points consecutively, or up to 8 clock points cumulatively, which are lesions that must be treated. 3. Advanced lesions with shallow or absent anterior chamber can be secondary to glaucoma and corneal degeneration. Clinical manifestations: The appearance of a demarcation line between the vascular and avascular areas of the retina at the early stage of the lesion is a unique clinical sign of ROP. Proliferative lesions at the demarcation, abnormal retinal vascular pathways, and varying degrees of retinal detachment with retraction, and late changes should be considered for the diagnosis of ROP. Screening criteria 1.For preterm and low weight infants with birth weight <2000g, screening for fundus lesions should be started and followed up until peripheral retinal vascularization; 2.For preterm infants with serious diseases, the screening scope can be expanded appropriately; 3.The first examination should be started at 4-6 weeks after birth or 32 weeks of corrected gestational age. IV. Treatment principles 1. Regular follow-up for stage 1 and stage 2 lesions in zone 3; 2. Close observation of pre-threshold lesions (any lesion in zone 1, stage 2+ in zone 2, stage 3, stage 3+); 3. Indirect fundoscopic photocoagulation or condensation for threshold lesions (stage 3+ lesions in zones 1 and 2 up to 5 consecutive bells, or up to 8 bells cumulatively); 4. Surgery for stage 4 and 5 lesions Treatment.