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).
Contact lenses are medical devices worn directly on the cornea of the eye. Like eyeglasses, contact lenses help to correct refractive errors, providing a safe and effective way to correct vision when used with care and proper supervision. For certain conditions, contact lenses may be considered medically necessary.