A three and a half year old child with 100 degrees of astigmatism is not very serious and is considered to have mild astigmatism. Astigmatism is a common disease in ophthalmology, mostly caused by congenital developmental abnormalities, and also has a certain relationship with bad eye habits, such as squinting for a long time to see things. The severity of astigmatism is categorized according to the degree of astigmatism. Astigmatism below 150 degrees is considered mild astigmatism, astigmatism between 150 degrees and 300 degrees is considered moderate astigmatism, and astigmatism above 300 degrees is considered high astigmatism. Children aged three and a half years old have poor cooperation in optometry, if the child’s cooperation is poor, such as not staring at the visual standard or squeezing the eyes, etc., the accuracy of optometry may be affected. 100 degrees of astigmatism is not serious, but it can be rechecked to see if it is due to measurement error.