Endocyclophotocoagulation

1. Essentials of Glaucoma Therapy
2. Lasers
3. Endocyclophotocoagulation

←Transscleral Cyclophotocoagulation

Surgical Iridectomy →

Primary authors	Nathan M. Radcliffe, MD Malik Y. Kahook, MD

LECTURE ON ECP: https://youtu.be/bsKXSDbX_jU

Introduction

As described in the section on transscleral cyclophotocoagulation (TSCPC), destruction of ciliary body tissue reduces aqueous humor formation and lowers intraocular pressure (IOP). Because the ciliary tissue cannot be directly visualized with this approach, the titration of the dose can be difficult, resulting in overtreatment (hypotony) or undertreatment, often necessitating multiple laser procedures. While this chapter is focused on the use of endocyclophotocoagulation (ECP) with cataract extraction (CE), this chapter also delves into the specifics of ECP and offers pearls for practice from our experience.

ECP is an ab interno (rather than transscleral) approach for cycloablation that utilizes the E2 microprobe laser and ­endoscopy system (Endo Optiks Inc, Little Silver, New Jersey) with an 810-nm diode laser, a 175-W xenon light source, and a helium neon laser-aiming beam. The single probe contains an endoscope attached to the laser, and this endoscope can also be used as a diagnostic tool because it allows for direct visualization of intraocular structures. Two probe sizes are available: the 20-gauge probe can provide a 70-degree field of view and a depth of focus ranging from 0.5 to 15.0 mm, whereas the 18-gauge system provides a field of view of 110 degrees, with a depth of focus ranging from 1 to 30 mm. Also, there are options between straight and curved probes, with the curved option providing greater ability to access more ciliary processes through a single incision.

Mechanism of Action

ECP causes coagulative necrotic damage to the ciliary body epithelium along with tissue contraction, sparing of the ciliary muscle, and minimal vascular destruction.1 In contrast, TSCPC causes more profound destruction of ciliary body architecture, including the ciliary body muscle.

Rationale

EPC (through a transcorneal approach) is one of a few incisional glaucoma­ surgeries that does not sacrifice conjunctiva that could be used for future filtration surgeries. Additionally, ECP does not invade Schlemm’s canal and does not eliminate future canal-based surgery (eg, canaloplasty). Furthermore, because hypotony and other severe complications seen with TSCPC are rarely seen with ECP, and because ECP can be combined with cataract surgery with minimal additional time and manipulation, ECP may have a role for glaucoma management earlier in the glaucoma spectrum than many other incisional surgeries.

Common Indications

1. Patients undergoing phacoemulsification who use 2 or more topical glaucoma medications with or without controlled IOP.
2. Patients with poorly controlled glaucoma despite maximal medical therapy and IOP under 35 mm, particularly in the presence of extensive conjunctival scarring from previous glaucoma surgery.
3. Eyes with opaque and failed corneas or keratoprostheses in which the ECP probe may be valuable for diagnosis and treatment.
4. Plateau iris syndrome with elevated IOPs and persistent angle closure after cataract extraction in which endocycloplasty has the potential to correct the ciliary malposition.

Relative Contraindications

1. Active uveitic glaucoma
2. IOP greater than 40 mm Hg

Necessary Equipment and Materials

1.  Twenty- or 18-gauge endoprobe with 810-nm diode laser, a 175-W xenon light source, and a helium neon laser-aiming beam
2.  Healon GV ophthalmic viscoelastic device (or other cohesive viscoelastic)
3. 15-degree paracentesis blade
4. Irrigation and aspiration unit
5. Balanced salt solution on a cannula
6. 10-0 nylon suture

Procedure

Obtain Informed Consent

In addition to a discussion of the patient’s glaucoma prognosis and the risks, benefits, and alternatives of continuing present management or alter-native procedures, such as incisional surgery, the patient should be informed that he or she may experience mild discomfort during the procedure; that the surgery is not guaranteed to be effective; and that complications, such as anterior segment inflammation and hyphema, are possible; in addition to other rare complications of incisional surgery, such as endophthalmitis or choroidal hemorrhage. Theoretically these risks are already present if the eye is being incised for cataract surgery at the same sitting.

Anesthesia

ECP may be performed with topical/intracameral anesthesia or after retrobulbar block (RBB). While RBB tends to provide exceptional intra-and postoperative pain control, the standard risks associated with RBB are present and must be considered. Topical anesthesia is performed in 2 stages, with topical lidocaine jelly applied to the cornea and into the superior and inferior fornices prior to preparing and draping the patient, followed by an intracameral injection of unpreserved lidocaine 1% into the anterior chamber for ciliary anesthesia just prior to ophthalmic viscoelastic device (OVD) placement and cyclophotocoagulation. Both RBB and topical approaches are performed with monitored anesthesia care with conscious sedation.

Surgical Approach

Figure 26-1. Ciliary processes are in view through the endoscope and appear white and shrunken after treatment.

A clear corneal incision is created with a 15-degree paracentesis blade. The phacoemulsification main wound may also be employed. Prior to the entry of the ECP probe, the anterior chamber is filled and the ciliary sulcus is inflated with Healon GV, depressing the capsule (or intraocular lens [IOL] and capsule if the patient is already pseudophakic) and elevating the iris with the cohesive OVD. Three probes are available: straight, curved (preferred by the authors), or hockey stick-shaped. In the case of combined ECP and cataract extraction, ECP is performed just prior to IOL insertion. ECP treatment with a curved probe is then performed for 270 degrees with 0.25-W of energy set on continuous mode, although 360-degrees of treatment can be achieved through 2 corneal incisions (100 degrees apart) for greater treatment effect. The clinical endpoint is blanching/whitening and shrinking of the ciliary processes (Figure 26-1). A slow and deliberate “painting” of the laser along the ciliary processes is preferred, rather than the delivery of discrete applications. The laser is applied to both the anterior and posterior extent of the ciliary processes, and any bubble formation is indicative that too much energy has been applied, either in duration, laser power, or proximity. Optimally, the ECP probe is held within 2 mm of the ciliary processes, and this location will typically allow 6 ciliary processes in the view of the endoscope. In the case of ECP for plateau iris syndrome, the laser is concentrated more on the posterior aspects of the ciliary processes and the clinical endpoint is the above, plus posterior­ rotation of the ciliary processes with deepening of the peripheral anterior chamber. After the treatment has been performed (and the IOL has been implanted), the OVD is removed and the anterior chamber is appropriately pressurized with balanced salt solution. All wounds are confirmed to be watertight, and standard postcataract medical therapy is initialized, usually with topical steroids, nonsteroidal anti-inflammatory drugs, and topical antibiotic.

Efficacy

In a head-to-head prospective comparison of ECP and Ahmed valve implantation in 68 eyes of 68 patients with refractory glaucoma, Lima et al found that after 24 months follow-up, the IOP was 14.73 ± 6.44 mm Hg in the Ahmed group and 14.07 ± 7.21 mm Hg in the ECP group (P = .7), with roughly 70% of patients in both groups achieving a successful outcome. Comparing complications between the Ahmed and ECP groups, there was a 17.6% versus 3.0% rate of choroidal detachment, a 17.6% versus 0% rate of flat anterior chamber, and a 14.7 versus 17.6% rate of hyphema, respectively. Gayton et al prospectively randomized 58 eyes of 58 patients to receive phacotrabeculectomy versus phacoemulsification/ECP. They found that 30% of ECP-treated patients achieved IOP below 19 mm Hg without medication and 65% achieved IOP below 19 mm Hg with medication, as opposed to 40% and 52% in the trabeculectomy group, respectively.

Conclusion

ECP, particularly when combined with cataract extraction, offers a safe and effective approach for IOP reduction in the glaucoma patient. The ­surgery is minimally invasive, does not eliminate future surgical options, and likely has a role earlier in the management of glaucoma patients than some other surgical options.

Key Points

1. ECP allows for focused treatment of the ciliary processes with minimal­ collateral damage.
2. ECP is often combined with cataract surgery but can also be effective as a stand-alone procedure.
3. As with other ab interno procedures, ECP does not cause scarring of the conjunctiva and thus does not negatively influence future filtration­ surgery if needed.