Modifier -24 is only used on e/m codes. you would use it if a patient has had a procedure/surgery on the right eye and is coming for a pre-op for the lt eye, you would append -24 on the exam code w/ -LT mod. The other use is if the patient had surgery/procedure on the right eye and then later comes in for a possible infection, injury etc.. (during global period of the 1st eye) on the left eye, you would append modifier -24 to the cpt code w/ add'l mod. of -LT.
for Modifier -79 you would use if the patient had surgery or procedure on right eye and during the gobal period of the 1st eye, they have the same procedure on the left eye. On the surgery/procedure code you would append mod. -79 w/ mod. -LT.
Modifier -57 is only used during an exam and the doctor decides this patient needs surgery either that day or the next day (w/in 24 hrs). Modifier -57 w/ the RT/LT would be appended to the exam code.
Didn't know if you needed clarification or not. Hope this helps.
Jennifer DeWitte, CPC, CPC-P, CPB
Newport Center Surgical
Coding & Billing Department