232

ophthalmologists with more extensive experience with cyclophotocoagulation have extended its indications, noting that the complication rates are lower than once believed (Scuderi et al., 1993; Gayton et al., 1999; Pastor et al., 2001). Cycloablation is still contraindicated, however, when safer options are available and in patients whose visual capacity is high.

Patient preparation

As with all parasurgical procedures, the patient must provide informed consent after the objectives and potential risks of the procedure have been presented and discussed. Cyclophotocoagulation procedures can be performed in an outpatient setting; local anesthesia can be achieved with a perior retrobulbar injection of 2% lidocaine+0.75% bupivacaine with hyaluronidase (50:50). During the preparation phase, systemically administered acetazolamide and/or mannitol can be prescribed to decompress the eye and reduce the risk of choroidal hemorrhage. During the preoperative phase, topical apraclonidine can be given to decongest the conjunctiva and reduce the risk of posttreatment increases in IOP (Chen and Ang, 2001).

Transpupillary cyclophotocoagulation

Introduced by Lee (1971), transpupillary photocoagulation allows destruction of the ciliary processes through the pupil or a wide surgical iridectomy. The laser spot can be focused on the ciliary processes directly or indirectly with the aid of a gonioscopy lens. This treatment is obviously reserved for eyes in which at least one third of the circumference of the ciliary processes can be clearly visualized, i.e., patients with maximum mydriasis, aniridia, wide surgical iridectomy, or retraction of the iris, which may be present in advanced forms of neovascular glaucoma.

Transpupillary cyclophotocoagulation is usually done with an argon laser; less frequently, diode laser is used. Argon lasers are used with a spot diameter of 100–200 mm, exposure time of 0.1–0.2 s, and 700–1000 mW of power; the effect is

seen as crater-shaped whitening of the ciliary process.

Transpupillary photocoagulation is not associated with an excessively high rate of complications; however, since its use is limited to rare cases, the transscleral approach is usually preferred.

Endoscopic cyclophotocoagulation

Treatments involving the ciliary processes have been further improved in recent years thanks to the introduction of small endoscopes (21-gauge) that use fiber optics for illumination, observation, and laser treatment. This approach, known as endoscopic cyclophotocoagulation (ecp) is considered a surgical method (Shields et al., 1985) because it requires that an instrument be introduced into the ocular bulb through the pars plana or the limbus. Its advantages include more precise visualization of the anatomic structure being treated, lower energy consumption (normally around 0.3 W per 1 s with around 60 applications) and reduced involvement of contiguous structures. ECP can be performed in association with phacoemulsification procedures (Uram, 1995).

Transscleral cyclophotocoagulation

Transscleral cyclophotocoagulation was introduced by Vucicevic et al. (1961). It involves the transmission of energy across the conjunctiva and the sclera without direct visualization of the ciliary bodies. It can be carried out with or without contact using either an Nd:YAG (continuousemission or pulsed) or diode laser. Pulsed lasers (Microrupter series) deliver short, high-energy pulses that provoke considerable tissue destruction; continuous-emission lasers (Surgical Laser Technologies, Oaks, PA, Lasag Microruptor III) require longer exposure times and produce coagulative effects. Diode units (Oculigt SLX and DC-3000) are contact-delivery systems; they requires longer exposure times than pulsed highenergy Nd:YAG units and produce tissue effects that are mainly coagulative.