In farsightedness, the image focuses beyond the retina. In our youth, the innate accommodating (focusing) power of the eye often compensates for farsightedness. But as we age, our eyes become less able to accommodate. For this reason, farsightedness most commonly becomes a problem later in life. Many farsighted eyes do not need correction until the individuals reach their forties or fifties.
Farsightedness can be corrected by any method that increases the total refractive power of the eye. Eyeglasses and contact lenses do this by putting in front of the eye "positive" lenses that are thicker in the center than at the edge. PRK does it by making the central part of the cornea more steeply curved.