For CPAP therapy to work effectively to treat sleep apnea, it is critical for your CPAP mask to fit properly. A proper mask fit allows your CPAP Machine to maintain the correct pressure and in the case of automatic machines effectively detect and treat CPAP events.
Secondly and most importantly you need to be comfortable wearing your mask. If you are not comfortable wearing your mask - the likelyhood is that you won't keep up your CPAP therepy and hence you won't be treating your sleep apnea. We have trained clinicians to advise you and find a mask fit your face and ensure it is a comfortable fit.