New or suddenly worsening myopia in the 40s may be due to age-related nuclear cataracts, or it may be just plain old myopia caused by overuse of the eyes. Although myopia can remain stable or slowly increase over a long period of time in adulthood, it cannot be ruled out that myopia continues to increase in adulthood due to the growth of the eye axis. This may be related to irrational eye use and genetic factors. There is also a case of lens clouding, especially nuclear cataract, which starts from the age of forty or even earlier, due to the rapid change of the refractive power of the density of the lens nucleus in a short period of time, which can be manifested as a sudden increase in myopia in a short period of time and blurring of vision. It is recommended that when myopia suddenly progresses or affects normal life in the forties, it is necessary to consult a doctor in a timely manner, and appropriate measures should be taken after perfecting naked-eye visual acuity, slit-lamp microscopy and other auxiliary examinations.