Question: If the physician performs SLT for glaucoma, which code should we report? What about if he performs ALT? Codify Subscriber Answer: Report any laser trabeculoplasty procedure-- whether it’s argon laser trabeculoplasty (ALT), diode laser trabeculoplasty (DLT), or selective laser trabeculoplasty (SLT) -- with 65855 (Trabeculoplasty by laser surgery). Note: The postoperative period for 65855 is 10 days. The short time period makes sense because ophthalmic surgeons often perform trabeculoplasties in two parts. Frequently, the entire 360 degrees is not performed at one time because this could raise the pressure. The standard protocol is to do 180 degrees first and the remaining 180 degrees in a later session. This reduces the amount of laser energy entering the eye. The 10-day global period means that the ophthalmologist can complete the procedure as soon as 11 days after the original session. There is no need to append a modifier to the CPT® code for the second trabeculoplasty surgery if it’s performed after the 10-day global period of the first surgery.