Here is a summary of common eye conditions and diseases experienced at different stages of adulthood. Some of these changes are normal, age-related developments. Others may be signs of a vision-threatening disease or condition. But all of these are reasons why the American Academy of Ophthalmology recommends that everyone start seeing an ophthalmologist at age 40 to ensure early diagnosis and treatment that may save your sight.
Beginning in the late 30s and early 40s, the lens in your eye loses flexibility, making it difficult to read up close. This condition is called presbyopia (which literally means "aging eye") and is commonly treated with over-the-counter reading glasses, though other treatments are also available.