Vision Problems
 

Contact lenses are better at correcting certain types of vision problems than others. Simple nearsightedness or farsightedness is usually easily corrected using contact lenses, but astigmatism can be more challenging to correct, especially with soft lenses. Contact lenses have varying success in correcting the need for reading glasses, with bifocal contact lenses being successful in only about 50% of people.

Toric soft lenses have an astigmatism correction built into the lens, but rotation of the lens can lead to a shifting of the astigmatism correction, and temporarily blurred vision. For people with severe or irregular astigmatism, gas-permeable lenses or hard lenses may offer better visual results. Irregular astigmatism is a situation where the cornea is distorted due to a scar or underlying disorder. Sometimes rigid contact lenses are the ONLY way to correct the vision in these cases, as even glasses will not help (as in keratoconus).

Many people who use contact lenses may experience halos around lights at night, and sometimes ghost images. This probably is a normal phenomenon in most people, and occurs when the pupil is larger (or more dilated) than the optical area of a soft lens, or of the lens itself in cases of rigid lenses. However, seeing a rainbow around lights indicates swelling of the cornea (corneal edema), and indicates that the lenses have been in too long and should be removed.

Blurred vision in one eye or the other with a contact lens that was previously clear could indicate a more serious eye problem, and should be checked by your doctor. Of course, it is possible that lenses can become switched between the eyes, but usually this is fairly obvious. An older lens can develop deposits and other surface problems which can make the vision not only blurry, but also can make the lens uncomfortable to wear.