Endoscopic cyclophotocoagulation (ECP) surgery for glaucoma lowers intraocular pressure (IOP) by decreasing aqueous production via direct laser treatment of the ciliary processes.1 Endoscopic cyclophotocoagulation was initially developed by Martin Uram in 1992,2 and it uses a single intraocular Endo Optiks probe (BVI) combining a diode endolaser, aiming beam, light source, and endoscope (Figure 1). Direct visualization and titration of power allow for controlled, targeted ablation of the ciliary process, which reduces collateral tissue damage (Figures 2 and 3).1 Histologic studies have shown that tissue injury is limited to the ciliary processes and associated capillary bed, sparing the ciliary muscle and stromal tissue.3
Other studies have reported IOP reductions between 2.7 mmHg and 11.5 mmHg, or between 14.9% and 46.9%, in glaucoma patients depending on whether ECP was done alone or in combination with cataract surgery.1 A comparison of ECP and phacomemulsification vs phaco alone with age-matched and IOP-matched groups was reported in a multicenter trial.4 In the study group of 80 eyes, the mean IOP decreased from a baseline of 18.1±3.0 mmHg to 16.0±2.8 mmHg at 1 year, and 16.0±3.3 mmHg at 2 years. The number of glaucoma medications decreased from 1.5±0.8 at 1 year to 0.4±0.7 at 2 years. In the control group of 80 eyes, the mean IOP was 18.1±3.0 mmHg at baseline, and it was reduced to 17.5±3.6 mmHg at 1 year and 17.3±3.2 mmHg at 2 years. The mean number of glaucoma medications was 2.4±1.0 at baseline, 1.8±1.2 at 1 year, and 2.0±1.0 at 2 years. The difference in IOP and medication reduction between the 2 groups was statistically significant at all timepoints.
As a procedure that reduces aqueous production, ECP should theoretically be additive to aqueous outflow surgery in reducing IOP, including angle-based microinvasive glaucoma surgeries. Microinvasive glaucoma surgeries (MIGS) have emerged as potentially favorable procedures to achieve better IOP control and/or to reduce medication burden with an excellent safety profile and better postoperative course compared to conventional glaucoma surgeries.5 The term “MIGS” generally refers to a group of procedures with characteristics such as minimal disruption of normal anatomy, high safety profile, good efficacy, and quick recovery time.6 MIGS is generally combined with cataract surgery and the procedures have been mostly reserved for patients with mild-to-moderate glaucoma because they do not reduce IOP as much as conventional incisional/filtering glaucoma surgeries. Data collected by the Centers for Medicare and Medicaid Services (CMS) show a significant trend toward MIGS over conventional incisional/filtering glaucoma surgeries. Out of 174,788 glaucoma surgeries that were performed in 2017, 11.4% were glaucoma drainage implants, 13.1% were trabeculectomies, and 75.5% were MIGS procedures.7 CMS data also show the number of MIGS procedures performed increasing by 426% over the period 2012 to 2016.8
Given the advantages of MIGS, it is possible to combine these procedures with ECP to achieve better IOP control by adding a procedure that lowers IOP via a different method. There are not yet many studies that have reported outcomes of combined MIGS procedures that include ECP. Studying patients with open-angle glaucoma, Ferguson et al compared the outcomes of patients who underwent combined microbypass stent implantation (the first-generation Glaukos iStent device), cataract extraction, and ECP (the “ICE-1 procedure”) to a group of patients who received the same microbypass stent with concomitant cataract surgery.9 The mean preoperative IOP was 21.49±9.56 mmHg in the study group (51 eyes) and 20.66±3.23 mmHg in the control group (50 eyes). Twelve months postoperatively, the mean IOP reduction was 7.14 mmHg in the ICE-1 group and 4.48 mmHg in the control group and the medication reduction was 38% (0.68) in the ICE-1 group and 63% (1.06) in the control group. The researchers also found the ICE-1 procedure was effective in patients with severe OAG.
In a retrospective single-arm case series study by Izquierdo et al, which included 27 eyes with both primary open-angle glaucoma and cataract, the authors reported the short-term to intermediate-term outcomes of combined phacoemulsification, ab interno goniotomy with Kahook Dual Blade (New World Medical), and ECP.10 After 9 months, IOP decreased from 17.0±3.7 mmHg at baseline to 11.4±1.8 mmHg (P<.001). Glaucoma medications decreased from 1.9±1.4 to 0.56±1.05 at 9-month follow-up (P<.001). The mean IOP reduction was 32.9% from baseline and the surgical success was 92.6% (complete success 70.3% and qualified success 29.6%) at 9 months. In another study, Klug et al compared the initial outcomes of patients with different types of open-angle glaucoma who either received the “PEcK procedure” (phacoemulsification, ECP, and ab interno goniotomy with Kahook Dual Blade) or the ICE-1 procedure over a period of 12 months.11 They reported the mean preoperative IOP was 18.3±5.9 mmHg in the PEcK group (53 eyes) and 14.7±4.3 mmHg in the ICE-1 group (23 eyes) (P=.004) on 3.3±1.3 glaucoma medications in the PEcK group and 1.7±0.93 glaucoma medications in the ICE-1 group (P<.001).
Twelve months postoperatively, the mean IOP reduction was 5.1±4.4 mmHg and 2.3±4.0 mmHg (P=.08), and the mean medication reduction was 1.6±1.5 in the PEcK group and 0.97±0.66 in the ICE-1 group (P=.10). The cumulative probability of success in the PEcK group was 93% at 6 months and 77% at 12 months postoperatively. The cumulative probability of success in the ICE-1 group was 96% at 6 months, and 85% at 12 months. There was not a significant difference in the survival functions of the 2 procedures (P=.41, log-rank test).
Conclusion
There is a trend in glaucoma surgery toward less invasive procedures with more favorable safety profiles, especially in the treatment of less severe disease or when combined with cataract surgery. In patients with lower target IOPs, however, one can consider combining a MIGS procedure with another surgery that works via a different mechanism. This could potentially lead to additive reductions in IOP and reduced dependence on glaucoma medications. Endoscopic cyclophotocoagulation, because it reduces aqueous humor production, may be an ideal additive procedure to angle-based surgery as a standalone, or combined with cataract surgery. GP
References
- Anand N, Klug E, Nirappel A, Solá-Del Valle D. A review of cyclodestructive procedures for the treatment of glaucoma. Semin Ophthalmol. 2020;35(5-6):261-275. doi:10.1080/08820538.2020.1810711
- Uram M. Ophthalmic laser microendoscope ciliary process ablation in the management of neovascular glaucoma. Ophthalmology. 1992;99(12):1823-1828. doi: 10.1016/s0161-6420(92)31718-x
- Francis BA, Flowers B, Dastiridou A, Yelenskiy A, Chopra V, Alvarado JA. Endoscopic cyclophotocoagulation and other cyclodestructive modalities: histopathological comparison of in vivo treatment in humans and monkeys. Ophthalmol Glaucoma. 2019;2(6):413-421. doi:10.1016/j.ogla.2019.08.008
- Francis BA, Berke SJ, Dustin L, Noecker R. Endoscopic cyclophotocoagulation combined with phacoemulsification versus phacoemulsification alone in medically controlled glaucoma. J Cataract Refract Surg. 2014;40(8):1313-1321. doi: 10.1016/j.jcrs.2014.06.021
- Birnbaum FA, Neeson C, Solá-Del Valle D. Microinvasive glaucoma surgery: an evidence-based review. Semin Ophthalmol. 2021;36(8):772-786. doi:10.1080/08820538.2021.1903513
- Saheb H, Ahmed II. Micro-invasive glaucoma surgery: current perspectives and future directions. Curr Opin Ophthalmol. 2012;23(2):96-104. doi:10.1097/ICU.0b013e32834ff1e7
- Ma AK, Lee JH, Warren JL, Teng CC. GlaucoMap — distribution of glaucoma surgical procedures in the United States. Clin Ophthalmol. 2020;14:2551-2560. doi:10.2147/OPTH.S257361
- Rathi S, Andrews CA, Greenfield DS, Stein JD. Trends in glaucoma surgeries performed by glaucoma subspecialists versus nonsubspecialists on Medicare beneficiaries from 2008 through 2016. Ophthalmology. 2021;128(1):30-38. doi:10.1016/j.ophtha.2020.06.051
- Ferguson TJ, Swan R, Sudhagoni R, Berdahl JP. Microbypass stent implantation with cataract extraction and endocyclophotocoagulation versus microbypass stent with cataract extraction for glaucoma. J Cataract Refract Surg. 2017;43:377-382. doi:10.1016/j.jcrs.2016.12.020
- Izquierdo JC, Mejías J, Cañola-R L, Agudelo N, Rubio B. Primary outcomes of combined cataract extraction technique with ab interno trabeculectomy and endoscopic cyclophotocoagulation in patients with primary open-angle glaucoma. BMC Ophthalmol. 2020;20(1):406. doi:10.1186/s12886-020-01643-2
- Klug E, Chachanidze M, Nirappel A, et al. Outcomes of phacoemulsification and endoscopic cyclophotocoagulation performed with dual blade ab interno trabeculectomy or trabecular micro-bypass stent insertion. Eye (Lond). 2022;36(2):424-432. doi:10.1038/s41433-021-01475-4