Endoscopic Cyclophotocoagulation (ECP) is a type of cyclodestructive procedure developed by Martin Uram in 1992. It involves inserting an endoscopic probe into the eye to directly visualize the ciliary processes and applying 810 nm semiconductor diode laser. This selectively ablates the ciliary epithelium, reducing aqueous humor production and lowering intraocular pressure.
Traditional cyclodestructive procedures (cyclocryotherapy and transscleral cyclophotocoagulation) did not allow direct visualization of the target tissue, leading to excessive tissue destruction. Complications such as prolonged hypotony, pain, uveitis, choroidal effusion, and phthisis bulbi occurred frequently 3). ECP minimizes collateral damage through precise direct visualization.
In the United States, ECP accounted for 47% of all cyclophotocoagulation procedures in 2005, increasing to 77% by 2012 1). In recent years, it has become common to perform ECP simultaneously with cataract surgery.
TSCPC delivers laser from outside the sclera, so the target cannot be directly visualized. ECP allows direct visualization of the ciliary processes via an endoscope, enabling fine adjustment of laser energy and reducing damage to surrounding tissues 1). Histologically, ECP causes more limited destruction than TSCPC, with a lower risk of hypotony and phthisis bulbi.
ECP is a treatment technique for glaucoma, not a disease itself. Glaucoma patients who are candidates for ECP present with the following symptoms and findings associated with elevated intraocular pressure.
ECP is indicated for a wide range of glaucoma types, including primary open-angle glaucoma, angle-closure glaucoma, pigmentary glaucoma, neovascular glaucoma, traumatic glaucoma, pediatric glaucoma, and other refractory glaucomas.
The main indications for performing ECP are as follows:
In glaucomas associated with elevated episcleral venous pressure (such as uveitic glaucoma and neovascular glaucoma), ECP may be more suitable than MIGS targeting Schlemm’s canal (e.g., iStent) 2).
ECP is a treatment for glaucoma, and preoperative diagnosis and examination follow the evaluation of glaucoma itself.
The ECP probe integrates the following three fiber groups1).
The probe is 18 to 23 gauge, with a 110-degree field of view and a depth of focus of 1 to 30 mm. The laser output is up to 2.0 W, typically using continuous wave irradiation at 100 to 300 mW.
Corneal Limbus Approach
Indications: Phakic and pseudophakic eyes. Recommended for simultaneous cataract surgery.
Incision: Requires 1.5–2.2 mm or larger. Both clear corneal incision and scleral tunnel incision are usable.
Features: Accesses the ciliary sulcus from the anterior chamber side.
Pars Plana Approach
Indications: Pseudophakic and aphakic eyes. Provides the widest view of the ciliary processes.
Anterior vitrectomy: Vitrectomy is essential in this approach.
Features: Used when expanding the treatment area to the pars plana with ECP Plus.
Stabilize the anterior chamber and deepen the ciliary sulcus with an ophthalmic viscosurgical device (OVD). Cohesive OVDs (Healon, Healon GV) are considered optimal. Dispersive OVDs provide insufficient space maintenance and tend to absorb laser energy.
Laser application is performed at a distance of approximately 2 mm from the ciliary processes. At this distance, about 6 ciliary processes are visible in the field. The target of irradiation is whitening and shrinkage of the ciliary processes, systematically treating each process with continuous wave while adjusting from low power.
To achieve sufficient intraocular pressure reduction, treatment of at least 270 degrees is necessary1)2). 360-degree treatment is considered superior to partial treatment in terms of IOP reduction, medication burden reduction, and treatment success rate.
For patients with both cataract and glaucoma, simultaneous lens reconstruction and ECP is widely performed1). phaco-ECP results in significantly lower intraocular pressure at all examination time points compared to lens reconstruction alone.
| Item | Phaco-ECP group | Phaco alone group |
|---|---|---|
| IOP difference (6 months) | −1.84 mmHg | Reference |
| Number of medications reduced | −0.75 medications | Reference |
This is an option for extremely refractory cases that have failed multiple glaucoma surgeries. In addition to standard ECP via a pars plana approach, the treatment area is extended 1–2 mm to the pars plana. It requires combined pars plana vitrectomy in pseudophakic or aphakic eyes.
The intraocular pressure reduction rate with ECP alone is reported to be 34–57% 1). Comparisons between cataract surgery combined with ECP and cataract surgery combined with trabeculectomy have shown similar success rates in both groups 1). Comparisons between ECP and the Ahmed glaucoma valve have also shown equivalent efficacy, with fewer complications for ECP 1).
Among MIGS procedures, ab interno trabeculotomy (AIT) may be superior to endoCPG in terms of intraocular pressure reduction 2). However, it has been pointed out that the treatment range in the included studies was often 180 degrees or less, and the recommended treatment of 270 degrees or more was not performed, which may have influenced this result.
The complication rate for endoCPG was 27 out of 156 eyes (17.3%), which was lower than that for iStent (23.0%) and AIT (53.7%) 2).
In recent years, phaco-ECP has been increasingly performed as a first surgery for patients with moderate glaucoma controlled by medication who also have cataracts. However, long-term randomized controlled trials are limited, and further evidence is needed for comparison with other surgical methods 1).
ECP irradiates the ciliary epithelium with an 810 nm diode laser, lowering intraocular pressure through the following two mechanisms 2).
This dual action is a characteristic of endoCPG and differs from iStent and AIT, which target only the outflow pathway2).
TSCPC causes extensive destruction of the ciliary processes and iris root, with occlusive vascular changes persisting for up to one month. In contrast, ECP causes only localized contraction of the ciliary processes. Although occlusive vascular changes also occur with ECP, partial reperfusion has been observed after one month. This partial recovery of blood flow is thought to contribute to the low incidence of hypotony and phthisis bulbi with ECP.
The main complications of ECP and their incidence rates (ECP Collaborative Study Group, 5,824 eyes, mean follow-up 5.2 years) are as follows.
| Complication | Incidence |
|---|---|
| Intraocular pressure spike due to viscoelastic material | 14.5% |
| Hyphema | 3.8% |
| Cystoid macular edema | 0.7% |
| Visual acuity loss of 2 lines or more | 1.03% |
Severe complications such as choroidal detachment (0.36%), retinal detachment (0.2%), hypotony (0.12%), and loss of light perception (0.12%) occurred only in eyes with neovascular glaucoma. No severe complications were reported in primary open-angle glaucoma or phaco-ECP.
For postoperative management after ECP, topical steroids and atropine eye drops are recommended 4). Early postoperative intraocular pressure monitoring should be performed, and glaucoma medications should be tapered.
Phthisis bulbi after ECP is extremely rare compared to TSCPC. In a large-scale survey by the ECP Collaborative Study Group, phthisis bulbi was reported only in neovascular glaucoma. However, because the risk of hypotony is approximately 7.5% with ECP Plus, its use in refractory cases requires careful consideration.
In systematic reviews and meta-analyses, phaco-MIGS (including endoCPG) showed superiority over phaco alone in terms of intraocular pressure reduction (WMD 1.22 mmHg) and medication reduction (WMD 0.59 medications), but the 95% confidence intervals crossed the line of no effect, requiring cautious interpretation2).
A 2019 Cochrane systematic review could not draw conclusions on whether cyclodestructive procedures for refractory glaucoma lead to better outcomes than other glaucoma treatments1)4). Another 2019 Cochrane review found no studies on ECP for open-angle glaucoma1). Further randomized controlled trials are needed to clarify the role of ECP1).
A meta-analysis (658 eyes) evaluating the efficacy of ECP for pediatric glaucoma showed that mean intraocular pressure in the ECP group decreased from 32.9±8 mmHg preoperatively to 22.6±9.8 mmHg at final follow-up (P < 0.0001). The treatment success rate was 53% over a mean follow-up period of 44.4 months.
