The most common method to distinguish between true myopia and pseudomyopia is dilated optometry. Pseudomyopia refers to an increase in the refractive error of the lens due to spasm of the ciliary muscles of the eye, resulting in myopia, but there is no organic lesion of the eye, and the eye can be returned to normal after intervention. If pseudomyopia is not corrected in time, it can develop into true myopia. True myopia refers to myopia caused by organic lesions of the eye, such as lengthening of the eye axis and excessive curvature of the lens. Pupil dilation optometry is performed in a state where drugs are used to completely paralyze the ciliary muscles and make them lose their adjusting effect. If the result of the pupil dilation optometry is that there is no refractive error, it means that the myopia is pseudomyopia. If there is still diopter after dilating the pupils, it means that this part of the diopter is true myopia. When you notice a decrease in vision, you should seek medical attention as soon as possible to improve your optometry and other tests to determine whether it is pseudomyopia or true myopia, so that you can intervene in a timely manner.