0-6 years old is a critical period for children’s visual development, once eye disease occurs during this period, without timely detection and treatment, it may cause serious consequences for the visual development of the child, or even lifelong visual disability. Therefore, early prevention and treatment is crucial. Since infants and young children cannot accurately express their discomfort, many eye diseases can only be detected and treated at an early stage by parents’ careful observation or by taking their children to the hospital for regular eye examinations. This requires parents to have a basic understanding of the common eye diseases in childhood so that they can detect any eye abnormalities early. So, what are the common eye diseases in childhood, we will give parents an introduction from the following aspects. 1, congenital eye diseases Congenital eye diseases have a great impact on the visual development of children, if not detected and treated in time, will cause children blind. Therefore, parents can not ignore such as congenital cataracts and other congenital eye diseases, especially those with a family history of congenital eye diseases. Congenital cataract manifested as the child’s pupil area whitening, poor tracking, is a common disease of white pupil, found should be operated as soon as possible; congenital glaucoma children manifested as large eyes, photophobia tears, once found should be operated as soon as possible; in addition, with the improvement of the level of treatment of premature babies, retinopathy of prematurity should not be ignored, if not detected in a timely manner, will result in childhood blindness. Therefore, for low-birth-weight preterm infants with a history of oxygen intake, eye examination should be routinely conducted to exclude retinopathy of prematurity. Strabismus refers to the inability of both eyes to focus on the target at the same time, which is a disease of extraocular muscles. It is generally divided into internal strabismus, external strabismus and up and down strabismus, but the most common ones are internal strabismus and external strabismus, and the external strabismus is what is commonly known as “squinting white eyes”, and the internal strabismus is what is commonly known as “opposite eyes”, which is commonly known as “opposite eyes”. External strabismus is commonly known as “squinting white eyes”, while internal strabismus is commonly known as “opposite eyes”, commonly known as “cock-eye”. The eye position is skewed inward, which is often called “opposite eye”. It is called congenital strabismus if it occurs from birth to less than 6 months after birth. Congenital esotropia is usually characterized by a large angle of deviation and usually requires surgical treatment at around 1.5 years of age. Acquired esotropia is divided into refractive and non-refractive esotropia. Refractive esotropia usually occurs in children between the ages of 2 and 3 years old, and is usually associated with moderate to high hyperopia, which can be corrected with eye wear. Children with non-refractive esotropia cannot be corrected with eyeglasses and require surgery. Exotropia The eye position is skewed outward and can be categorized into intermittent and constant exotropia. Intermittent esotropia is characterized by good fusion ability, which maintains the eye position in a normal position most of the time, and only occasionally shows an esotropic eye position in sunlight or when fatigue occurs. Some children also show a tendency to close one eye in strong sunlight. A large proportion of children with intermittent esotropia will develop constant esotropia. These children can be observed or trained in convergence and fusion. If the strabismus is prolonged and no binocularity is present, surgery is usually required to restore binocularity and stereopsis development. Constant exotropia, as the name suggests, requires surgical treatment as the child’s eyes are always in an exotropic position and cannot be controlled to an upright position. Upper and lower strabismus: The eye position is upward or downward deviation, which is less common than inward and outward strabismus. Due to paralysis of extraocular muscles, this kind of children can see double, and in order to overcome diplopia, they adopt special head position such as tilting the head, side face, lifting the chin, and so on, which is known as “compensatory head position” in medical science. For children, this not only affects aesthetics, but also leads to malformation of the whole body bone development. Many parents find their children with “crooked necks” and think that it is due to abnormal neck development, but in fact, many of them are caused by paralyzing strabismus. Therefore, when these children go to the orthopedic department, they should not forget to see the ophthalmologist to rule out strabismus. This type of strabismus usually requires surgery. Strabismus is not difficult to diagnose and it is easy for parents to notice, but many parents have misconceptions about the treatment of strabismus, believing that their children are too young to undergo corrective surgery and that they should wait until they are older, or even that strabismus can be improved slowly. As the strabismus eye is unable to gaze normally, the image of the strabismus eye is blurred, forming inhibition, leading to poor visual development and causing amblyopia. The deviation of the eye position also causes the loss of binocular vision, so when the child’s eye position is deviated, the binocular vision function is also lost, and it is impossible to form binocular monovision, resulting in the lack of stereoscopic vision, which has a great impact on the child’s future life and learning. As strabismus affects the aesthetics of the child, children with strabismus are often nicknamed, which casts a shadow on the child’s psyche and causes him or her to be withdrawn and psychologically abnormal. Therefore, once a child is found to have strabismus, he/she must be taken seriously and should go to the hospital as soon as possible for diagnosis and treatment. Amblyopia refers to the best corrected visual acuity in one eye or both eyes which is lower than the corresponding age visual acuity, or the difference of visual acuity in both eyes is two or more lines, due to monocular strabismus, uncorrected refractive error and high refractive error, and visual deprivation during visual development. The lower limit for different ages: 0.5 for 3-5 years old, 0.7 for 6 years old and above. Amblyopia is usually categorized into: Strabismus amblyopia: amblyopia caused by monocular strabismus; Refractive Parallax Amblyopia: the difference between the two hyperopic spherical lenses is 1.5DS, and the difference between the two column lenses is 1.0DC, which can cause amblyopia to develop in one eye of the eye with the higher refractive error; Refractive error amblyopia: it occurs mostly in the patient with a high degree of refractive error who does not have refractive corrective lenses. It mainly occurs in patients with high hyperopia or astigmatism in both eyes, and the best-corrected visual acuity of both eyes is equal or similar. It is generally recognized that hyperopia ≥5.00DS and astigmatism ≥1.0DC increase the risk of developing amblyopia; Formal deprivation amblyopia: caused by deprivation factors such as refractive interstitial clouding and ptosis. Amblyopia can be unilateral or bilateral, with unilateral being more severe than bilateral. Untreated amblyopia can seriously damage a child’s future quality of life. In the process of promotion and recruitment every year, a considerable number of students lose their chances due to amblyopia, which not only directly affects the child’s college entrance examination and career choice, but also affects the child’s physical and mental health. Therefore, we often say that the harm of amblyopia is much greater than that of myopia, because myopia can be corrected with glasses to achieve normal vision, which does not affect the child’s future work and study, but if amblyopia is not detected and treated at an early stage, even if the child grows up and wears glasses, his/her eyesight will still be permanently low, and he/she will become a lifelong disability. The treatment of amblyopia emphasizes early detection and early treatment. There are many ways to treat amblyopia, including fine training (such as threading needles, beads, tracing, etc.), amblyopia trainer treatment (red light flicker therapy, after-image therapy, etc.), synoptic machine training, etc. However, all these treatments are based on the premise that amblyopia can be treated with glasses when it grows up, which is a permanent disability. However, all of these treatments presuppose proper refractive correction under ciliary body paralysis, i.e., amblyopia training must be under the precondition of eye wear. Amblyopia intervention is usually most effective before the age of 8 years, and the efficacy of amblyopia treatment decreases with age. Therefore, once found amblyopia should be treated as soon as possible, do not let the child lose an important weight in the future life because of eyes. 4, myopia myopia refers to the eye in the state of relaxation, parallel light (generally believed to be from 5m away) through the refractive system of the eye focusing on the retina before the scattered and fuzzy aperture, this refractive state is called myopia. The main symptom of myopia is the loss of distance vision, that is, seeing clearly near and blurring far. In order to see the objects in front of you clearly, you need to move the objects closer or wear myopic eye correction. In recent years, the rate of myopia in children and young people has been increasing, and the age has dropped significantly, with some children having to wear eyeglasses from kindergarten onwards because they suffer from myopia. Unlike farsightedness caused by underdevelopment of the eyeballs, myopia is the result of overdevelopment of the eyeballs. This, coupled with the fact that children nowadays use their eyes too much at an early age, and use their eyes frequently at close distances, such as reading books and looking at computers, has led to an increase in myopia. Therefore, early prevention and treatment of myopia is crucial. Parents should pay attention to observe the child’s usual eye habits, remind the child to watch TV can not sit too close and do not lie down to see, it is recommended to look away for ten minutes after watching TV for half an hour. Reading and writing conservative correct posture, distance and time, more outdoor activities, especially let the child to learn the correct posture of the pen, found that the child likes to tilt the head, squinting to see things, or watching TV closer, like to rub the eyes, etc. are to be highly suspicious of the child’s eyesight may be abnormal. To go to the hospital in time to do eye examination, vision abnormalities should be corrected in time with glasses. Hyperopia is a refractive state in which a parallel beam of light 5 meters away is refracted by the relaxed eye and imaged in the retina. Hyperopia occurs when the refractive power of the eye is insufficient or the length of the eye axis is insufficient. Farsightedness is characterized by difficulty in seeing both near and far, and is often characterized by visual fatigue due to over-adjustment of the eye. Most children are born with some degree of hyperopia, but it disappears by age 12. Hyperopia often premature children have difficulty reading at close range and develop dyslexia visual fatigue. When comparing the eyes of children with hyperopia to the eyes of children with normal refraction, the eye length is usually shorter and the refractive power of the lens is weaker. Therefore, we believe that hyperopia does not imply a “bad eye”, but only indicates that the child’s eyeball development is relatively backward, the eye axis is relatively short, and the shape of the eyeball is a bit abnormal. Children suffering from hyperopia should be optometrically fit as early as possible. Parents who find that their children do not like to read, complain of blurring of handwriting when reading for a little longer, eye swelling, headache, lack of concentration, frequent blepharitis, granuloma, chalazion, conjunctivitis, should pay attention to it, and should check whether the child’s vision is abnormal. If it is determined that farsightedness (including farsightedness astigmatism), we must grasp the golden opportunity before the age of 8 years, under the ciliary body paralysis dilated pupil optometry with the appropriate glasses, do not delay. Otherwise, after the age of 12 years old, prescription glasses, visual acuity will be very difficult to improve, not to mention the restoration of binocular synoptic function. Therefore, children’s eye disease is important in the early detection, early diagnosis and treatment, do not let the child because of the eyes and lose at the starting line. In addition, attention should be paid to pregnancy protection, family history of disease should be eugenic counseling, to reduce the occurrence of congenital eye disease.