Whether or not conical cornea develops at age 40 is related to the condition and the time of onset; it usually develops slowly after age 40, but it can develop in severe cases. Conical cornea is an eye disease caused by genetic and acquired factors, and is characterized by a dilated, centrally thinned cornea that protrudes forward in a conical shape. Cases with early onset are usually more severe, and if the onset is relatively late, the disease develops relatively slowly in the later stages, but whether it still develops at age 40 is related to the patient’s condition. Patients with conical cornea in the early stages can improve their vision by wearing eyeglasses. In the later stage of cone cornea patients with glasses vision correction is not good, the patient can be treated by surgery to improve vision, patients need to avoid rubbing the eyes, do a good job of eye cleaning. It is recommended that patients with conical cornea should consult a doctor in time to assess their condition and under the guidance of the doctor.