In some cases, mild farsightedness can be treated with simple magnifying lenses or "reading glasses". However, an optometrist may need to prescribe a dioptre for both eyes or each eye, allowing lenses to be custom ground to the patient's specific needs. Usually, the dioptre (or "prescription") is equal for both eyes; in some cases, however, the two eyes may need different prescriptions.
Some patients benefit from bifocals, or lenses with separate sections ground to different prescriptions for different circumstances. Typically a person with myopia would have one section of a prescription lens that has a certain diverging power while another section of the lens would have a lower diverging power for close-up work. Similarly a person with hypermetropia would have one section of the lens with a certain converging power and another section with a greater power for close-up work.
It is essential for those who wear eyeglasses or contact lenses to consult their optometrists regularly to ensure that their prescription remains constant, especially in the case of children.