I have found endoscopic cyclophotocoagulation (ECP), the controlled ablation of ciliary processes under direct endoscopic visualization, to be a very useful adjunct in glaucoma treatment. I feel that it may be underutilized by the glaucoma community because it has been likened to trans-scleral cyclophotocoagulation (TCP) in which laser energy is delivered through the sclera and ciliary body muscle to the ciliary processes without visual guidance or feedback. The only evidence of treatment effect is a “popping” sound, which is in fact the ciliary process exploding in a shower of blood, fibrin, and debris. However, I still recommend TCP in patients that cannot undergo an intraocular surgery, or who have very poor visual potential.
ECP has been shown by histological evaluation to be a treatment that is limited to the ciliary process, and mostly to the ciliary epithelial bilayer. TCP, in contrast, causes permanent damage (coagulative necrosis) to the ciliary processes, ciliary body and in some cases, sclera. Hyptony is extremely rare, and phthisis has not been described with ECP, in contrast to TCP.
Clinically, I use it where an inflow procedure would be useful. A good example is in cases where an outflow procedure has been performed but is inadequate (such as an aqueous shunt or trabeculectomy). It has been extremely helpful in the treatment of ocular burn or severe ocular surface disorder patients. These individuals have complete scarring and closure of their outflow pathways, and filtering surgeries are unlikely to be successful due to severe abnormalities of the conjunctiva. At the Ocular Burn Rehabilitation Center at the Doheny Eye Institute, we have adopted ECP as the mainstay of glaucoma treatment. It has also been used with success in keratoprosthesis patients with severe ocular surface disease.
There are some clinical pearls to treatment. Most cases of failure from ECP are from undertreatment. One should treat until there is shrinkage and whitening of the entire visible ciliary process, not stop as soon as shrinkage begins. I believe that a full 360 degrees of treatment is needed to get a significant IOP reduction, due to the fact that the ciliary epithelium is not completely treated even with a 360 degree treatment (unlike TCP). The epithelium is usually inaccessible in between the processes, and is difficult to reach as the process extends posteriorly into the pars plicata. In a combined cataract extraction, treating through the capsular bag filled with viscoelastic prior to IOL implantation gives a good view, better than over the edge of the bag. Certainly the best view is obtained via a pars plana approach (combined with a limited pars plana vitrectomy such as that advocated in complicated cataract extraction). This approach requires a continuous infusion into the eye instead of viscoelastic.
The surgical endoscope also has other uses besides the delivery of laser energy. It is helpful in the evaluation and closure of cyclodialsis clefts, lysis of goniosynechiae, and evaluation of a malpositioned IOL thought to be causing uveites, glaucoma, hyphema (UGH) syndrome. I have also used it to view the ciliary processes in patients with hypotony, to evaluate the processes in their natural state for atrophy or cyclitic membrane.
One caveat to the procedure is that although it is much better tolerated than TCP, it is still not without potential problems. It causes inflammation and possibly cystoid macular edema, and steps need to be taken to prevent this. Frequent post operative steroid drops, topical NSAIDs and even intracameral steroid at the end of the procedure are helpful in this regard. Complete removal of viscoelastic is essential to prevent an IOP spike, and manual (Simcoe) or automated irrigation and aspiration are preferred to simple washout.
In conclusion, ECP has a place as a very valuable tool in glaucoma treatment as the best available aqueous inflow treatment. If proper technique and patient selection are followed, it is a very effective surgical option and should eventually be used by an increasing number of glaucoma specialists.
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