A child with 300 degrees of myopia may be pseudomyopic, but the probability is relatively small because the myopia of a person with pseudomyopia is usually low. Pseudomyopia is often due to the usual excessive use of the eyes leads to ciliary muscle continuous contraction, spasm, which causes an increase in the thickness of the lens, resulting in temporary myopia. children under 12 years of age, the eye regulation is strong, prone to pseudomyopia, so children with 300 degrees of myopia may be pseudomyopia. However, the likelihood of a child with 300 degrees of myopia being pseudomyopia is low. Generally, the degree of pseudomyopia is low, and a dilated optometry is needed to determine whether it is pseudomyopia. It is recommended that children with myopia seek medical attention to evaluate their condition and follow the doctor’s instructions for treatment.