The first time you get a pair of eyeglasses, you need a prescription for them. If you need to replace any part of your glasses at a later time, you could probably do that without a prescription. Same goes for CPAP masks. Complete CPAP Masks systems require a prescription. However, you have the option to purchase a mask in parts (headgear + mask without headgear = complete mask system). The parts do not need a prescription.
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The first time you get a pair of eyeglasses, you need a prescription for them. If you need to replace any part of your glasses at a later time, you could probably do that without a prescription. Same goes for CPAP masks. Complete CPAP Masks systems require a prescription. However, you have the option to purchase a mask in parts (headgear + mask without headgear = complete mask system). The parts do not need a prescription.