Retinopathy of prematurity (ROP) is a condition in which the unvascularized retina of a preterm infant with low birth weight and prolonged oxygenation undergoes fibrovascular proliferation and constriction, and further causes retinal detachment and blindness by traction. It was previously referred to as Terry syndrome or posterior lens fibrodysplasia, but the latter reflects only the late manifestations of the disease. The incidence can be 60% to 80% in those with shorter gestation periods or lower birth weight. ROP commonly occurs 3 to 6 weeks after birth and is clinically divided into the active phase and the fibrous membrane formation phase. 1, the active phase (1) vascular change stage for the early course of retinopathy of prematurity seen. The arterioles are tortuous and dilated. The venous diameter is sometimes 3 to 4 times larger than normal. Brush-like capillaries can be seen at the end of the vessels in the peripheral part of the retina. (2) Retinopathy stage The lesion develops further, the vitreous becomes cloudy and the fundus is hazier than before. The retinal neovascularization increases, mostly located near the equatorial part, but also seen before the equatorial part or in the posterior pole. The retina in this area is obviously elevated, with blood vessels crawling on its surface, often accompanied by retinal hemorrhages of different sizes. (3) Early proliferative stage The above-mentioned limited retinal bulge appears as proliferative vascular strips and progresses intravitreally, causing a small retinal detachment in the peripheral part of the fundus (most) or the posterior pole (a few). (4) Moderate hyperplasia stage The detachment extends to more than half of the retina. (5) Extreme proliferation stage Total detachment of the retina. Sometimes a large accumulation of blood in the vitreous cavity can also be seen. The active stage of retinopathy of prematurity has a duration of 3 to 5 months. Not all cases go through the above 5 stages, about 1/3 cases stop in the first stage, 1/4 stop in the second stage, and the rest stop in the third, fourth and fifth stages respectively and enter the fibrous membrane formation stage. 2.Fiber film formation period In cases that cannot subside on their own during the active period, they finally scarred and formed fiber film, which is divided into 1 to 5 degrees from mild to severe depending on the degree: degree I: retinal blood vessels are thin and narrow, the peripheral part of the retina is gray and cloudy, mixed with small irregularly shaped pigment spots, and the nearby vitreous body is also cloudy, often accompanied by myopia. Grade II: organic masses in the peripheral part of the retina, the optic disc and retinal vessels are pulled to one side, there are pigment arcs on the edge of the contralateral optic disc, and the optic disc is discolored. Degree III: The fibrous mechanized membrane pulls on the retina to form one or several folds. Each fold is connected to a membrane-like mechanized mass in the peripheral part of the retina. The retinal vessels are not distributed along this fold, unlike the congenital retinal folds. Grade IV: The fibrous membrane or detached part of the mechanized retina is visible behind the lens and the pupil is obscured. Grade V: The entire posterior lens is covered by the fibrous membrane or detached mechanized retina. On dilated pupil examination, a jagged elongated ciliary process is visible in the peripheral part of the pupil. The anterior chamber is very shallow, often with anterior and posterior iris adhesions. The eye may also be cloudy due to secondary glaucoma or extensive anterior iris adhesions, and the eye is smaller and more sunken than normal. Once the disease occurs, it progresses rapidly and has a narrow window of time to be effectively treated, so premature infants under 37 weeks of age should be examined promptly after birth, and those at high risk should be examined weekly. In stages 2 to 3, laser or cryotherapy is feasible to coagulate the avascular area. In stages 4 to 5, vitreous surgery is performed to remove proliferating fibrovascular tissue and photocoagulation is done at the same time to save vision.