Contacts are thin, clear discs that float on the tear film that coats the cornea, the curved front surface of the eye. Contacts correct the same refractive conditions eyeglasses correct: myopia (nearsightedness), hyperopia (farsightedness) and astigmatism (an oval- rather than round-shaped cornea).
Contact lenses can be made from a number of different plastics. The main distinction among them is whether they are hard or soft. Most contact lens wearers in the United States wear soft lenses. These may be daily wear soft lenses, extended wear lenses or disposable lenses. Toric soft lenses provide a soft lens alternative for people with slight to moderate astigmatism.
Hard lenses are usually not as comfortable as soft lenses and are not as widely used. However, rigid gas permeable lenses provide sharper vision for people with higher refractive errors or larger degrees of astigmatism.
The majority of people can tolerate contact lenses, but there are some exceptions. Conditions that might prevent an individual from successfully wearing contact lenses include dry eye, severe allergies, frequent eye infections, or a dusty and dirty work environment.
Individuals who wear any type of contact lens overnight have a greater chance of developing infections in the cornea. These infections are often due to poor cleaning and lens care.
There are two main types of lens care systems: heat and chemical disinfection. The appropriate choice depends on the lens type, duration of lens wear and an individual's own biochemistry. Regardless of the type of disinfection system you choose there are a number of common steps that must be followed.
Always wash your hands prior to handling your contact lenses.
Remove one lens and place it in the palm of your hand. Apply a few drops of a contact