Changing moderate profile to high profile ?

This depends
somewhat upon the implant manufacturer. These measurements I’m providing are
based upon the Allergan moderate profile saline (style 68) implant, which most
accurately matches your description. The base measure of a 420 cc moderate
profile implant is 13.4 cm. It could be slightly narrower if the implant has
been filled more than 420 ccs. If you go to the high profile 550 cc Allergan
implant (style 20), the base diameter is 13.5 cm. Thus, it is unlikely there
will be any change in cleavage based upon those measurements, though you will
obtain greater projection and upper pole fullness. In addition, your breasts
will appear somewhat less natural as a result.

Thank you for the question. You will find that online consultants will not be able to provide you with specific advice in regards to selection of specific breast implant size/profile.  Adjustment of the breast implant capsules may also be necessary.

Ultimately, careful communication of your goals (in my practice I prefer the use of goal pictures, direct examination/communication in front of a full-length mirror, and computer imaging) will be critical.

Generally speaking, the best online advice I can give to ladies who are considering revisionary breast augmentation surgery (regarding breast implant size/profile selection) is:

1. Concentrate on choosing your plastic surgeon carefully. Concentrate on appropriate training, certification, and the ability of the plastic surgeon to achieve the results you are looking for. Ask to see lots of examples of his/her work.

2. Have a full discussion and communication regarding your desired goals with your plastic surgeon. This communication will be critical in determining breast implant size/type/profile will most likely help achieve your goals.
In my practice, the use of photographs of “goal” pictures (and breasts that are too big or too small) is very helpful. I have found that the use of words such as “natural” or "D or DD cup” or "upper pole fulness" etc means different things to different people and therefore prove unhelpful.
Also, as you know, cup size varies depending on who makes the bra; therefore, discussing desired cup size may also be inaccurate.

3. Once you feel you have communicated your goals clearly, allow your plastic surgeon to use his/her years of experience/judgment to choose the breast implant size/profile that will best meet your goals. Again, in my practice, this decision is usually made during surgery ( after the use of temporary intraoperative sizers). Viewing the patient's chest wall in the upright and supine positions, with temporary sizes in place, help select the best breast implant size/profile for the specific patient.

I hope this, and the attached link (dedicated to revisionary breast augmentation surgery concerns), helps. Best wishes.