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).
If your eye doctor recommends and prescribes disposable bifocal contact lenses, an estimated per-box cost for these lenses is $50 to $70 (similar to the cost of disposable toric contacts). So again, an annual lens cost of $500 to $700 is not unusual if you wear the lenses daily and replace them every two weeks. number of factors can change this estimate, including: Astigmatism. Contact lenses that correct astigmatism cost more than soft contacts that only correct nearsightedness or farsightedness. Soft contact lenses for astigmatism, called toric contacts, frequently retail for $50 to $70 for a box of six lenses.