Since ECP is a targeted laser procedure under direct visualization, laser energy can be delivered in short titratable bursts with rest intervals, allowing for a tissue effect while minimizing collateral energy absorption.⁴

Even though ECP is a highly controlled procedure, laser energy that is delivered to the ciliary processes still has the potential to cause a significant amount of postoperative inflammation. The laser energy may also contribute to the breakdown of the blood-aqueous barrier, especially in cases of overly intensive treatment, mechanical trauma to intraocular tissue by endoscope manipulation, or other technical challenges.⁶ Therefore, any patient who is already experiencing an active case of uveitic glaucoma or uveitis, in general, should not have the ECP procedure performed. The additional postoperative uveitis may make the patient’s underlying inflammation much more difficult to control.

A more relative contraindication in doing ECP would be patients with IOP greater than 40 mm Hg. These patients would be considered to have severe glaucoma and
would benefit most from trabeculectomy or tube shunt glaucoma surgery. If vitreous is present in the anterior chamber, it must be removed prior to the ECP procedure.⁶ The vitreous will interfere with manipulation of the endoscope as the vitreous will get entangled around it.

Finally, eyes with end-stage glaucoma, and severely compromised outflow (e.g., eyes that have neovascular glaucoma with complete involvement of the angle) are also poor candidates for ECP.¹⁰

The lens status, whether the patient is phakic, aphakic, or pseudophakic, dictates which surgical approach can be utilized. There are two main approaches to the ciliary processes. The anterior segment approach utilizes either a scleral tunnel or clear corneal incision. These are the typical surgical approaches used in combination ECP with phacoemulsification cataract extraction since these incisions have already been performed for the cataract extraction part of the combined surgery (Fig. 15.3).
As long as there is no vitreous in the anterior chamber, ECP can be performed as a stand-alone procedure in phakic, aphakic, or pseudophakic eyes.

The posterior segment approach accesses the ciliary processes from the pars plana (Fig. 15.4). This approach is amenable for both aphakic and pseudophakic eyes. It cannot be safely performed in phakic eyes since the natural lens interferes with access to the ciliary processes. The anterior vitreous must be removed with a vitrector before the endoscope can be introduced through the pars plana incision.⁴ Further discussion of the posterior segment approach is beyond the scope of this chapter.

The ciliary processes are very sensitive, so adequate anesthesia must be attained. General anesthesia is reserved for pediatric glaucoma patients. For all others and those having combination ECP with cataract extraction, the standard local anesthesia will suffice. This includes retrobulbar, peribulbar, or intracameral (non-preserved lidocaine injected into the anterior chamber).³ Intracameral anesthesia helps the patient tolerate the surgical microscope light, in addition to reducing sensation in the ciliary body.¹¹ Purely topical anesthesia is insufficient.

Currently, the only commercially available glaucoma ECP device is the Endo Optiks E2 Ophthalmic Laser and Endoscopy System by BVI Medical. It consists of two components: the laser microendoscope and the laser endoscopy system (console) (Fig. 15.5). The most commonly used laser endoscope for the treatment of glaucoma contains a single, 19-gauge curved cannula (Fig. 15.6). There are two types of 19-gauge endoscopes: straight and curved. Both 20-gauge and 23-gauge cannula options are available but only as straight endoscopes. The clinician should be able to treat up to 180° of the ciliary body circumference using the straight endoscope, and up to 240° using the curved endoscope, through a single surgical incision (Fig. 15.7). To treat beyond 240° and up to 360° requires at least two surgical incisions. To achieve an adequate drop in IOP and derive a long-term benefit, at least 270° to 300° of treatment needs to be applied.⁶

The E2 Ophthalmic Laser and Endoscopy System incorporates an 810 nm diodelaser, which emits continuous energy, and a helium-neon red laser aiming beam (Fig. 15.8). The initial power setting is typically set at 0.25 W. If the treatment effect
is not adequate at this setting, the power level can be increased incrementally by 0.05 W until the desired tissue change is observed. The clinician controls the amount of total laser energy to be delivered by way of a footswitch. When the footswitch is depressed, the laser will fire and when it is released, laser delivery ceases.⁶ The laser application is aimed at individual ciliary processes to produce a visible whitening and
shrinkage of the entire anteroposterior extent of the process (Fig. 15.9).¹² Disrupted or scar tissue should not be treated. The average duration of direct laser application per ciliary process is around 0.5 to 2.0 seconds.¹² An alternative treatment approach is to “paint” the tissue by sweeping across the arc of the ciliary ring. Usually, several passes are required to treat most of the surface of each process.⁶ Bubble formation and ciliary process “popping” is indicative of excessive energy application. This can result from holding the endoscope too close to the ciliary process or having the power setting turned up too high.⁷ The ECP endoscope is usually held within 2 to 3 mm of the ciliary processes, allowing visualization of approximately four to six ciliary processes at a time (Fig. 15.10).¹³ The 19-gauge endoscope incorporates a 17k pixel image fiber, with a 140° field of view and has a focus range from 1.5 mm to infinity. The image is delivered via the video camera and a 175 W xenon light source housed in the E2 system.¹³,¹⁴ The clinician views the video monitor instead of looking through the operating microscope.