Astigmatism is distorted vision caused by an unevenly curved cornea. The cornea is the clear outer layer on the front of the eye. As a result of astigmatism, your vision is somewhat blurry all the time.
Regular contact lenses do not correct the blurry vision caused by astigmatism. Astigmatism can be corrected with special lenses called toric lenses. Toric lenses change the shape of your cornea and make it more even. This produces better vision. Toric lenses are usually thicker and heavier at the bottom. This keeps the lens in the correct position on the eye. Like regular lenses, toric lens may be soft or gas permeable. Fitting toric contact lenses takes more time and expertise than regular contacts. Toric lenses are also usually more expensive.
For some people, contact lenses correct astigmatism better than eyeglasses do.
Presbyopia is the natural loss of clear close-up vision as you get older. Around the age of 40, the lenses of your eyes start to be less flexible. This causes the eye to be unable to focus sharply on close objects. You may need to hold things farther away from your eyes to see them clearly.
People who wear contact lenses can wear contacts to see at a distance and a pair of reading glasses to see close objects. It is also possible to correct presbyopia with contacts.
With monovision, you wear a contact lens in one eye for seeing distances and a lens in the other eye for reading. Monovision takes time to get used to. Your brain must learn to "see" with one eye at a time, and you may have problems with depth perception. Monovision does not work for everyone.
There are several types of bifocal contact lenses:
You may adjust quickly to bifocal contacts, but you may have some problems. You may feel that your vision is not as clear as you are used to, or it may change when the lens moves on your eye. You may see images that seem to jump when you change from distance to close-up vision, a three-dimensional effect or ghost image when you read, or a halo around lights. Problems like these can sometimes be corrected with a change in lenses. Sometimes the problems may get better as you get used to the new lenses.
If problems continue with lenses, presbyopia can also be corrected with bifocal glasses. Bifocals have the distance prescription on the top and the reading prescription on the bottom.
You may need to try several different types of lenses. Contacts come as soft lenses and gas permeable (GP) lenses. Your eye care provider can recommend which type you should try, and trial lenses can be ordered.
Choosing which type of contact lens is best for you is based on: