Presbyopia ? the gradual loss of your eyes' ability to focus actively on nearby objects. A basic eye exam can confirm presbyopia. You can correct the condition with nonprescription reading glasses or prescription eyeglasses or contact lenses. Surgery also may be an option.

If you have presbyopia, you may:

• Find that print appears unclear at a normal reading distance
• Experience eyestrain or headaches from prolonged reading or close work.

Treatment:

The goal of treatment is to compensate for the inability of your eyes to focus on nearby objects. Treatment options include wearing corrective lenses, undergoing refractive surgery or getting lens implants.

Corrective lenses

• Prescription reading glasses. If you have no other vision problems, you can have prescription lenses for reading only.

• Bifocals. These glasses come in two styles — those with a visible horizontal line and those without a line (progressive bifocals). When you look through progressive bifocals at eye level, the lenses correct your distance vision. This correction gradually changes to reading correction at the bottom.

• Trifocals. These glasses have corrections for close work, middle-distance vision — such as for computer screens — and distance vision. Trifocals can have visible lines or progressive lenses.

• Bifocal contacts. Bifocal contact lenses, like bifocal glasses, provide distance and close-up correction on each contact. The bottom, reading portion of the lens is weighted to keep the lens correctly positioned on your eye. These are frequently difficult to fit and often do not provide altogether satisfactory visual results.

• Monovision contacts. With monovision contacts, you wear a contact lens for distance vision in your dominant eye and a contact lens for close-up vision in your nondominant eye. Your dominant eye is generally the one you use when you're aiming a camera to take a picture.

• Modified monovision. With this option, you wear a bifocal contact lens in your nondominant eye and a contact lens set for distance in your dominant eye. You use both eyes for distance and one eye for reading. Your brain learns which lens to favor — depending on whether you're viewing things close up or far away — so you don't have to consciously make the choice of which eye to use.

Refractive surgical procedures include the following:

• Conductive keratoplasty (CK). This procedure uses radio frequency energy to apply heat to very tiny spots around the cornea. The degree of change in the cornea's curvature depends on the number and spacing of the spots, as well as the way in which the corneal tissue heals after the treatment. The results of CK are variable and unstable in many people.

• Laser-assisted in-situ keratomileusis (LASIK). With this procedure, your eye surgeon uses a laser or an instrument called a keratome to make a thin, hinged flap in your cornea. Your surgeon then uses an excimer laser to remove inner layers of your cornea to steepen its domed shape. An excimer laser differs from other lasers in that it doesn't produce heat.

• Laser epithelial keratomileusis (LASEK). Instead of creating a flap in the cornea, the surgeon creates a flap only in the cornea's thin protective cover (epithelium). Your surgeon will use an excimer laser to reshape the cornea's outer layers and steepen its curvature and then reposition the epithelial flap.

• Photorefractive keratectomy (PRK). This procedure is similar to LASEK, except the surgeon removes the epithelium. It will grow back naturally, conforming to your cornea's new shape.