Question: Would it be appropriate to bill for both 66180 and 67255 at the same OR session and same eye for an aqueous shunt insertion and a scleral reinforcing graft? Our physicians aren't sure. Kansas Subscriber Answer: Because the ophthalmologist doesn't have to perform 67255 on every patient who gets a shunt, be sure the documentation includes information about the scleral thinning or other reason for the reinforcement procedure to support medical necessity for the additional procedure. Note: You may need to append modifier 51 (Multiple procedures) to 67255, depending on your carrier, because your physician performed more than one procedure during the same operative session. Medicare doesn't require you to use modifier 51 on a Medicare claim because the carrier will automatically add it, but you'll likely need the modifier for private payers. Link the appropriate glaucoma diagnosis to 66180 for the shunt insertion, and link 379.04 (Scleromalacia perforans) to 67255 for the graft.