Question: When should I use +67331? I have been told in the past to only use the code if the patient has had a different type of eye surgery leading to the strabismus, not a previous strabismus surgery, but I can’t tell if this is accurate. Tennessee Subscriber Answer: CPT® code +67331 (Strabismus surgery on patient with previous eye surgery or injury that did not involve the extraocular muscles (List separately in addition to code for primary procedure)) is an add-on code, which can only be reported in conjunction with a primary procedure code — in this case, a strabismus surgery code from the 67311-67318 range. It is meant to describe the ophthalmic surgeon’s extra work in planning and performing strabismus surgery on patients who have had previous eye surgery. According to CPT® Assistant, “There is increased difficulty of planning and performing strabismus surgery on eyes that have had previous surgery or have been injured. Code +67331 is reported with the definitive strabismus surgery now being performed. If both eyes have had prior eye surgery or injury, the 50 modifier (Bilateral procedure) is appended to +67331. If the same strabismus surgery code is reported for both eyes, the 50 modifier is also reported with the code for the definitive strabismus surgery.”