CPT 66183 (Insertion of anterior segment aqueous drainage device, without extraocular reservoir, external approach), is a modification on trabeculectomy procedures for treating medication–refractory IOP in glaucoma patients. This procedure is accomplished by creation of a scleral flap in the first step and implantation of a device in the second step followed by closure of the flap as a watertight seal. After adequate anesthesia induced by retrobulbar or modified topical technique, and prep and drape with Betadine and lidocaine gel, a stay suture is placed at the limbal position, and usually lidocaine mixed with epinephrine is injected into the operative part of the eye as a sub–tenon injection. The provider creates a fornix–based partial thickness scleral flap or alternatively may use only a limbal peritomy to create a limbal–based scleral flap. In limbal–based scleral flap creation, an incision along the superior limbus area may be utilized to separate conjunctiva from the scleral surface, and then a partial–thickness scleral flap is raised in that area. Mitomycin–C followed by irrigation is utilized at this junction. A needle tract is created into the anterior chamber, and the device or implant is slipped under the scleral flap to reach the anterior chamber through this needle tract. A fornix–based scleral flap, on the other hand, is raised through a fornix incision made parallel or perpendicular to the fornix of the eye. In this technique, a deeper flap may be created to involve the Schlemm's canal and by excising the inner wall of the canal via canalplasty. In both cases the device is placed through the scleral flap into the anterior chamber, and the scleral flap is then closed and sealed in a watertight manner. This shunt device allows passage of aqueous humor from the anterior chamber to the subconjunctival bleb and helps maintain the desired intraocular pressure. The common devices used in this technique are Express miniature glaucoma implant, Solx Gold Shunt implant, Aquashunt implant, etc.
In the CPT 0449T (Insertion of aqueous drainage device, without extraocular reservoir, internal approach, into the subconjunctival space; initial device), typically by topical anesthesia, the provider makes a small fornix–based corneal incision (under the eyelid on the cornea, the clear transparent covering of the front of the eye) or a limbus–based corneal incision (on the cornea near its junction with the sclera, the white of the eye). He places the aqueous drainage device, e.g., a Baerveldt® glaucoma implant or an Ahmed® glaucoma valve, into the interior of the eye so that it drains into the space under the conjunctiva, i.e., the interior lining of the eyelids and external lining of the eyeball. No reservoir is implanted. The provider controls any bleeding and closes the incision in the cornea.
CPT 0049T is a Category III code temporary for emerging technology, services, procedures, and service paradigms. Category III codes allow data collection for these services/procedures. Use of unlisted codes does not offer the opportunity for the collection of specific data. If a Category III code is available, this code must be reported instead of a Category I unlisted code.
Since you have a defined code for insertion of anterior segment aqueous drainage device, so need not to bill a temporary code. However, the approach of both the codes (66183 & 0449T) are different, CPT 66183 is of external approach for anterior segment and CPT 0449T is of internal approach into subconjunctival space. When billing for same eye you need to make your documentation strong enough to support the medical necessity. Also, as per CCI edits guidelines, code 0449T is a column 2 code for 66183, modifier is allowed in order to differentiate between the services provided. Use modifier 59 with code 0449T to override the edits. On the other hand, if you are performing the procedure on different eye, then both the code can be billed together with modifiers LT and RT for left and right eye.
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