Endoscopic Cyclophotocoagulation (ECP)
Endoscopic cyclophotocoagulation (ECP) is a surgical procedure that effectively inhibits the production of aqueous fluid in the eye by the ciliary epithelium. ECP uses a similar laser to transcleral cycloablation but involves direct visualization of the ciliary processes and precise treatment to achieve a predictable effect.
Intraocular view of the endoscope and ciliary processes.
Some observers concerned about the safety of ECP group its risk into the same category as transscleral cyclophotoablation. To address this incorrect assumption, an international ECP Study Group was formed to conduct a retrospective review of the safety of this procedure. In total, 5,824 patients were treated and followed for a mean of 5.2 years (range 1-10.5 years). Early complications included IOP spike (14.5%) and intraocular hemorrhage (3.8%). Long term complications included cystoid macular edema with visual loss in 0.27%, retinal detachment in 0.27% and massive choroidal hemorrhage in 0.09%. Hypotony or phthisis occurred in 0.12%, and only in patients with neovascular glaucoma. These complication rates are lower than other types of incisional glaucoma surgeries. Less than 1% of patients suffer vision loss following ECP, compared with 5-10% following trabeculectomy and 10% following tube (shunt) surgery. There is no increased risk of cystoid macular edema in ECP patients compared with control groups (i.e. phacoemulsification). Conversely, there is a 5-10% risk of CME in patients following trabeculectomy. And finally, there has not yet been a reported case of endophthalmitis following an ECP procedure. Comparatively, there is a 1% risk of endophthalmitis following tube (shunt) placement and a 1% risk PER YEAR of endophthalmitis following trabeculectomy surgery. Of the most devastating complications, including endophthalmitis, lens dislocation, choroidal hemorrhage, phthisis, and retinal detachment, the COMBINED risk is less than 1% for ECP. ECP has been performed globally for over 12 years, with more than 50,000 patients treated to date. An endoscope is used to view the interior of the eye utilizing a fiberoptic image and camera. Utilizing a probe less than 1mm in diameter, the endoscope allows easy entry through small incisions, such as those used during cataract surgery. This allows visualization and treatment of areas of the eye that were previously impossible to access. The laser microendoscope allows for simultaneous viewing and treatment through a single incision by integrating a unique fiberoptic bundle. Imaging and laser delivery are combined in a single instrument, as is the case with other types of endoscopic treatments.
The surgical endoscope used during ECP is less than 1mm in diameter, making it one of the world’s smallest surgical endoscopes.
Surgical view of ciliary processes treated with ECP. The red aiming beam is seen centrally.
During the treatment, the ciliary processes are viewed on an external monitor. The ciliary processes resemble finger-like folds and lie in a circular array along the underside of the iris. ECP decreases the production of aqueous by ablating the ciliary processes with direct laser application. The infrared laser used operates at 810nm, a wavelength which is selectively absorbed by the pigmented surface cells of the ciliary epithelium. This tissue shrinks and whitens as it is treated. ECP can be performed individually or as a combined procedure at the time of cataract surgery. During cataract surgery, the lens is removed from the capsule during phacoemulsification. The endoscope is then inserted through the same incision as is used for cataract surgery, and the ciliary processes are viewed and treated with the laser.
Since ECP was pioneered in the early 1990s, it has been utilized and perfected worldwide for more than 10 years. It has been proven to be one of the most successful and safest surgical treatments for glaucoma in the world today. ECP is minimally invasive, has an outstanding safety record with uncomplicated follow-up, fast recovery, and predictably improved outcomes. Greater than two out of three patients with POAG treated with ECP will reduce the number and/or frequency of glaucoma medications. And about half are able to discontinue them! This results in improved compliance and control, with lower prescription costs. Furthermore, patients with systemic symptoms from medical therapy (i.e. beta blockers such as timolol) will often feel more energetic after discontinuation of these drops. Clinical studies over the past 10 years have confirmed that over 90% of ECP patients benefit from a clinically significant reduction in their intraocular pressure. 50-55% of patients are able to discontinue their glaucoma medications following ECP. Nearly 70% of glaucoma patients are able to reduce the number and/or frequency of glaucoma medications, resulting in a significant cost savings.
In the most recently published large scale study, Dr. Stanley Berke and colleagues reported the results of more than 600 combined cataract and ECP cases on patients with both glaucoma and cataracts whose intraocular pressure was controlled by 2 or more medications and were followed for up to 5 years. In this controlled, randomized study, 626 combined cataract/ECP eyes were compared with a cohort of 81 eyes with glaucoma and cataracts who underwent cataract surgery alone. The purpose of the study was four fold. First, they wanted to delineate the natural history of phacoemulsification and its effect on intraocular pressure in the setting of medically controlled glaucoma, since cataract surgery alone sometimes results in a reduction of IOP. Second, they wanted to determine if ECP, when used in conjunction with phacoemulsification, results in long-term lower intraocular pressure, fewer glaucoma medications used, or both compared to phacoemulsification alone. Third, they wanted to determine if adding ECP to phacoemulsification increases surgical and post-operative risk compared to phacoemulsification alone. Fourth, they wanted to calculate the cost benefits, if any, resulting from long-term decrease in glaucoma medications following ECP. The mean follow-up for all patients was 3.2 years with a range of 0.5 to 5.8 years, extending from January 2000 to December 2004. All patients were treated from 200 to 270 degrees with a 20 gauge endoscopic probe utilizing a diode laser to whiten and shrink the visualized ciliary processes. The long-term effect on intraocular pressure is shown in the table and graph below. In the 626 combined phaco/ECP patients, the preop IOP was 19.08mm Hg compared to a decrease to 15.73 at the end of the study period. This was highly statistically significant. Similarly, the number of preop medications in the phaco/ECP group was 1.53. This was reduced to 0.65 at the end of the study period. The post-operative effect on intraocular pressure and medications used was not statistically significant in the 81 patients who had phacoemulsification alone.
In the phaco/ECP group, 68% of patients had a decrease in glaucoma medications. In 27% there was no change and in 5% there was an increase. This compares to an 11% decrease in medications in the phaco alone group, with a 77% incidence of no change in medications, and a 12% increase (see figure below).
Taken another way, in the phaco/ECP group, 44% were on 2 or more glaucoma medications preoperatively. Postoperatively, this fell to 18%, a statistically significant change. In the phaco alone group, 32% of patients were on 2 or more medications preoperatively, and at the end of the study 38% were on 2 or more medications (see table below).
In the phaco alone group, there was a decrease in intraocular pressure in 38%, no change in 2%, and an increase in 60% at the end of the study. Conversely, in the phaco/ECP group, there was a decrease in IOP in 79%, no change in 9%, and an increase in 12% (see figure below).
The cost benefit analysis also strongly supports the use of ECP in conjunction with phacoemulsification. In this study, the average annual cost of glaucoma medications for patients in the phaco/ECP group was $2,641 preoperatively and $1,137 postoperatively, a savings of $1,504 per patient per year. The phaco alone group did not appreciate any financial savings. Extrapolation to the entire US population could easily provide cost savings in the hundreds of millions of dollars, in addition to the benefits in reduced need for self medication and subsequent improvement in compliance.
ECP does not cause the undesirable side effects and unpredictability of any of the conventional surgical procedures and offers an exciting option for the future of safe, effective surgical treatment of glaucoma.