For any given substance, the heat capacity of a body is directly proportional to the amount of substance it contains (measured in terms of mass or moles or volume). Doubling the amount of substance in a body doubles its heat capacity, etc.
Conventional soft contacts can last up to a year; conventional rigid gas permeable (RGP) contact lenses can last even longer. Frequent or planned replacement contact lenses last one to several months. Disposable contacts last from one day (daily wear) to up to two weeks (extended wear).
In the late 1980âs and early 1990âs, soft disposable lenses came onto the market making it more affordable and convenient for people to wear contact lenses. These lenses were designed to wear for up to two weeks, one month, or one quarter depending on the type of lens design.