Final answer:
The appropriate CPT code for creating a custom prosthesis from an impression of a left orbital socket is 21076. Other codes mentioned are for different procedures or do not specify custom preparation.
Step-by-step explanation:
The correct code for the service of taking an impression of a 47-year-old woman's left orbital socket and creating a custom prosthesis is 21076.
When it comes to CPT (Current Procedural Terminology) coding, each code pertains to a specific medical procedure. The code 21076 is used when a physician prepares an impression and custom preparation of an ocular prosthesis, which may involve the left or right orbital area, and it does not need a modifier for a specific side unless the payer's guidelines require it. Code 21089 is used for alloplastic material preparation, which is not the case here, and the code 21088 is for preparing a non-custom prosthesis, which also does not apply. Lastly, code 21077 is for prosthetic reconstruction of the mandible, which is unrelated to the orbital socket.