Corrective lenses are lenses that are worn over the eye to help the eye focus so that it can see clearly. Many people all over the world need to wear corrective lenses in order to have good vision, and there are a number of different types of lenses available. A doctor can determine whether or not a patient needs corrective lenses with a routine eye exam, and the exam can also be used to arrive at a prescription for a specific pair of lenses.

The first corrective lenses were eyeglasses, made by mounting glass lenses in a frame which is worn on the face. In the 20th century, researchers developed contact lenses, which are inserted into the eye to correct vision. It is also possible to surgically implant a permanent lens, as may be done after the removal of cataracts. Further developments have led to eye glasses with lenses made from plastic instead of glass, for increased durability.

Someone who is nearsighted or myopic needs corrective lenses which will move his or her focal point further away, making it possible to see things in the distance. Farsighted or hyperopic individuals need lenses which bring the focal point closer, so that they can see objects in their proximity. This can be accomplished by wearing a curved lens to cause the light to refract before it hits the eye. The depth of the curve, the thickness of the lens, and the precise shape of the lens can all be used to change the focal point. As anyone who has tried on someone else's glasses knows, small differences in lens design can radically change someone's vision.

There are other uses for corrective lenses. People who suffer from astigmatism can wear lenses which will compensate for the defect in the eye which causes the astigmatism, allowing them to see clearly. Double vision can also sometimes be corrected with lenses, as can specific vision problems in certain situations, such as the inability to read up close, a common problem in older individuals.

An ophthalmologist or optometrist can prescribe corrective lenses to a patient. Wearing lenses can radically improve quality of life, allowing the patient to clearly see what is going on and reducing problems such as headaches and squinting which are associated with the need for corrective lenses. In some nations, people with corrective lenses may also be required to comply with certain restrictions, such as not driving without wearing corrective lenses.