Ophthalmology and Optometry Coding Alert

Question: A patient presented with alternating esotropia (378.05). The ophthalmologist performed strabismus surgery on one horizontal muscle in each eye. Should we report 67312?
     
Michigan Subscriber Answer: When surgery is performed on one horizontal muscle in the left eye - say, the lateral (temporal side) rectus muscle or the medial (nasal side) rectus muscle - and the lateral rectus or medial rectus muscle in the right eye, code the single horizontal muscle on each eye on two lines: 67311 (Strabismus surgery, recession or resection procedure; one horizontal muscle) and 67311-50 (Bilateral procedure) or 67311-RT (Right side) and 67311-LT (Left side). Do not use 67312 for this procedure.
 
Code 67312 (... two horizontal muscles) is appropriately valued lower than 67311 billed bilaterally. Reporting 67312 for 67311 bilaterally is improper coding that will cost reimbursement.
 
For vertical muscles, things are more complicated. If one vertical muscle - the superior rectus or inferior rectus
- is operated on, report 67314 (... one vertical muscle [excluding superior oblique]). If two vertical muscles are operated on in the same eye, use 67316 (... two or more vertical muscles [excluding superior oblique]).
  
"Two or more vertical muscles" might lead one to believe that this is a bilateral code. There are technically only two vertical muscles in one eye, but CPT considers the inferior oblique muscle a vertical muscle for coding purposes.