The Nd:YAG laser (Surgical Laser Technologies Inc., Malvern, PA., USA) was one of the first used to do TCP. The probe is rounded and the energy delivery is through the center. Placement of the center of the probe is 1–2 mm posterior to the limbus, which can be measured by calipers but is often estimated visually. Energy levels are started at about 7 W and 0.7 s and are titrated to avoid an audible “pop” that indicates overtreatment and explosion of the ciliary body tissue. A total of 17–20 spots are usually applied to treat 270° of ciliary processes, avoiding the 3 and 9 o’clock positions (Table 9.1).

After the procedure, atropine and dexamethasone ointments are applied and the eye is patched. The patch may be removed in the evening and glaucoma drops should be reinstituted. Prostaglandin analogs may be excluded in the short term if cystoid macular edema (CME) is a concern, and cholinergics should be temporarily discontinued to avoid increased inflammation. Postoperative prednisolone acetate 1 % is applied 4 times daily for 10–14 days and tapered according to inflammation.

The diode laser (IRIS Oculight SLx, Iris Medical Inc., Mountain View, CA, USA) (Fig. 9.1a) emits at 810 nm, and the probe has a tip shaped as a footplate (Fig. 9.1b). The heel of the footplate is placed adjacent to the limbus, and the laser tip is positioned 1.2 mm behind to be over the ciliary body. The laser tip, which protrudes 0.7 mm, should be applied firmly against the conjunctiva/sclera to help avoid conjunctival burn. The treatment principles are similar to the Nd:YAG laser. The initial energy settings are often about 1,000 mW with 2 s duration (Table 9.1). Lower energy levels can be used with longer durations. The 3 and 9 o’clock positions are avoided and a total of 17–20 shots are applied over approximately 270°. Energy is titrated to be just below that needed to achieve the “pop” sound. The number of treatment spots and avoidance of the 3 and 9 o’clock positions are similar to that for the Nd:YAG laser.

The laser unit for ECP (Endo Optiks, Little Silver, NJ, USA) incorporates a diode laser that emits pulsed continuous-wave energy at 810 nm, a 175 W xenon light source, a helium-neon laser aiming beam, and video camera imaging, which can be recorded (Fig. 9.2a). All four elements are transmitted via fiber optics to an 18-gauge or 20-gauge probe (Fig. 9.2b), which is inserted intraocularly. The optimum focus for the laser is 0.75 mm from the probe tip, and the endoscope provides a 70° field of view. The main unit is compact and portable, with a maximum power output of 2.0 W. Controls for laser power and duration (up to 9.99 s) are adjustable on the console. The foot pedal controls laser firing with the actual duration of each treatment determined by how long the pedal is depressed.

The two main approaches to reach the ciliary processes are via a limbal or a pars plana entry. The limbal approach is preferred because anterior vitrectomy and associated risks for choroidal and retinal detachment are avoided. However, there are some cases that are more safely treated through the pars plana, for example, in aphakic eyes with posterior synechiae limiting access to the ciliary sulcus. In both situations, a retrobulbar block with lidocaine and bupivacaine is performed or general anesthesia can be considered in selective cases.

In the limbal approach, after dilation of the pupil with cyclopentolate 1 % and phenylephrine 2.5 %, a paracentesis is created and the anterior chamber is filled with viscoelastic agent, which is further used to expand the nasal posterior sulcus. This viscoelastic expansion of the posterior chamber allows for easier approach to the pars plicata with the ECP probe. A 2.2-mm or 2.5-mm keratome is then used to enter into the anterior chamber at the temporal limbus. After orientation of the probe image outside of the eye, the 18-gauge or 20-gauge probe is inserted through the incision and into the posterior sulcus. At this time, the ciliary processes are viewed on the monitor and treatment can begin. The laser is set at continuous wave and energy settings are 300–900 mW (Table 9.1). Approximately a 180° span of ciliary processes is photocoagulated (more area can be treated if a curved probe is used). Laser energy is applied to each process until shrinkage and whitening occur. Ciliary processes are treated individually or in a “painting” fashion across multiple processes. If excessive energy is used, the process explodes (or “pops”) with bubble formation, leading to excessive inflammation and breakdown of the blood-aqueous barrier. After the nasal 180° of ciliary processes are treated, a separate incision is created at the nasal limbus in a similar fashion as above. The temporal processes are then photocoagulated for a total of up to 360°, if so desired. Typically, 180–360° are treated [46–48, 57]. The authors’ preference is to treat 270–360° of processes. Before closure of the wounds, viscoelastic is removed from the anterior chamber with irrigation and aspiration.

In all patients, whether under local or general anesthesia, retrobulbar bupivacaine is administered before or at the end of the surgery to minimize postoperative pain. Sub-Tenon’s injection of 1 mL of triamcinolone (40 mg/mL) is also given for inflammation. On postoperative day 1, patients are placed on a regimen of topical antibiotics, steroids, nonsteroidal anti-inflammatory agents, cycloplegics, and their preoperative glaucoma medications except for miotics and prostaglandin analogs because these may exacerbate intraocular inflammation or its sequelae. Antibiotics are discontinued after 1 week, and the steroids, nonsteroidal anti-inflammatory agents, and cycloplegics are tapered as inflammation subsides. Glaucoma medications are removed according to the IOP requirements. Administration of acetazolamide during the evening of surgery may be used to prevent a spike in IOP from underlying glaucoma, inflammation, or possible retained viscoelastic.