Bifocals are dual-vision glasses that allow the patient to see two different vision prescriptions through the same lens. Bifocals can often be identified because they look like a normal glasses lens with a portion of another lens resting on top, either in a circular or sliver shape. Newer bifocals blend the two lens prescriptions together so bifocal lenses are less detectable. Patients who need bifocal lenses are usually nearsighted and also have presbyopia, an inability to focus on nearby objects that often occurs during middle age.
Determine how far away you hold your reading material. If you wear glasses or contact lenses, but must hold your newspaper or book at an arm's length in order to read it, you may need bifocals.
Ask a partner to see if you are squinting while using the computer or reading. You may not be aware you are squinting, but if your partner observes that you are, you may be having difficulty focusing on close objects due to presbyopia.
Consider your age. Most patients develop presbyopia between the age of 40 and 60, the Mayo Clinic reports. If you are in this age range, your chances of developing presbyopia are high.
Hold a newspaper 1 foot from your face, then slowly move it farther away as you attempt to focus on the printed words. If the text becomes more clear as the paper is moved away, you may need bifocals.
See an optometrist. A routine optometrist appointment will determine whether you need bifocals and whether you have developed presbyopia. Your eye doctor may give you a range of treatment options, including bifocals, bifocal contact lenses or laser surgery.