Question: Arkansas Subscriber Answer: If the patients intraocular pressure (IOP) is being monitored because the patient has chronic glaucoma, you can definitely bill the postoperative visit separately because a glaucoma check is not considered related to cataract surgery. You should include a primary diagnosis code of glaucoma and link it to the service code, and bill the glaucoma visit with modifier -24 ( On the other hand, if the patients IOP is being checked because it has increased as a result of the cataract surgery, this service is considered related to the cataract surgery and is therefore considered included in the global surgery fee for the initial procedure. Under these circumstances, you should not bill the IOP check separately. Dont make the mistake of under-documenting services that you are billing separately during a global period. If the documentation doesnt clearly identify the postoperative visit as unrelated to the surgery, you are asking for trouble in the event of an audit. .