Endoscopic cyclophotocoagulation and Kahook Dual Blade trabeculotomy in combination with phacoemulsification

Abstract

Convenient to perform alongside cataract surgery and relatively safe, minimally invasive glaucoma surgeries (MIGS) are growing in popularity. Few studies have examined the effect and safety of performing combined MIGS. We examined the outcomes of combining two distinct MIGS: endoscopic cyclophotocoagulation (ECP) and ab interno trabeculotomy with Kahook Dual Blade (KDB; New World Medical, Rancho Cucamonga, Calif), along with phacoemulsification cataract extraction with intraocular lens placement (PEIOL). ECP is a cyclodestructive procedure with the goal of treating the ciliary processes to disable the aqueous-producing ciliary epithelium. ECP tends to be more durable in older patients. Younger patients tend to require re-treatment as either the epithelium returns or the residual epithelium increases function. KDB treatment aims to remove trabecular meshwork in a more complete fashion than alternative forms of ab interno trabeculotomy. The suspected location of greatest resistance to outflow, the juxtacanalicular meshwork, is included in this treatment. By decreasing aqueous production with ECP and increasing aqueous outflow with KDB, we hypothesize intraocular pressure (IOP) may decrease, in an additive fashion, more than with either procedure alone while maintaining a low side effect profile. All eyes in this case series were diagnosed with mild to moderate open-angle glaucoma (OAG) and a visually significant cataract. All eyes underwent ECP, KDB, and PEIOL. PEIOL was performed first, then ECP over approximately 270 degrees of the ciliary processes, with sparing of the temporal quadrants, and KDB for approximately 90 degrees of the nasal quadrant. Data were collected and de-identified for analysis. Data included visual acuity (VA), IOP, number of medications, and complications. Data were recorded at the preoperative visit and then at 1 day, 1 week, and 1, 3, 6, and 12 months postoperatively. Averaged data at each follow-up time point were compared to preoperative data using a paired t test. The limit of statistical significance was set at p < 0.05. Ten eyes from 7 patients were examined in this series. The average patient age was 68 ± 7 years, and the distribution of males and females was equal (see Table 1). Patients were Caucasian (70%), Asian (20%), and African American (10%). Only 1 eye had received prior laser treatment with selective laser trabeculoplasty. Mean historical maximum IOP was 25.3 ± 3.7 mm Hg. At the preoperative visit, mean IOP was found to be 18.6 ± 3.9 mm Hg, and patients were on a mean of 2.1 ± 1.4 IOP medications, which included varying combinations of latanoprost, timolol, dorzolamide, and brimonidine. Preoperative Humphrey visual field mean deviation was –4.38 ± 4.85 dB. No eye lost vision as a result of surgery, and all patients had a best corrected VA of 20/20 or better at 12 months.Table 2Intraocular pressure and medications over time (mean ± standard deviation)Mean IOP (mm Hg)Absolute IOP reduction (mm Hg)Percent IOP reduction (%)Medications (n)Absolute medication reduction (n)Preoperative18.6 ± 3.9——2.1 ± 1.4—3 months16.0 ± 3.1–2.6 ± 2.6 (p = 0.012)–12.6 ± 13.0 (p = 0.013)1.0 ± 1.2–1.1 ± 1.4 (p = 0.040)6 months13.9 ± 3.2–4.7 ± 3.7 (p = 0.003)–23.8 ± 16.5 (p = 0.001)0.8. ± 0.9–1.3 ± 1.2 (p = 0.017)12 months14.7 ± 2.4–3.9 ± 4.2 (p = 0.017)–18.0 ± 18.5 (p = 0.013)0.8 ± 0.9–1.3 ± 1.1 (p = 0.004)IOP, intraocular pressure Open table in a new tab IOP, intraocular pressure Mean IOP from postoperative month 3 to month 12 ranged from 13.9 to 16.0 mm Hg (see Table 2). Absolute mean reduction in IOP by 12 months was 3.9 ± 4.2 mm Hg (p = 0.017), or an 18% ± 18.5% (p = 0.013) decrease. The number of IOP medications decreased to 1.0 ± 1.2 by postoperative month 3 and was 0.8 ± 0.9 by postoperative month 12. Absolute reduction in medications was 1.3 ± 1.1 (p = 0.004), or a 68.5% ± 34.9% decrease (p < 0.001).Table 1DataPreopPOM3POM6POM12IOPMedAgeSexRaceTmIOPMedsIOPMedsIOPMedsIOPMeds∆ %*∆ % = Percent IOP reduction∆ #†∆ # = Change in IOP mmHg∆ # %‡∆ # % = Percent IOP reduction∆ #§∆ # = Change in number of IOP medications used78FA22203151151161–20%–4–67%–278FA22203161151161–20%–4–67%–265FC221441611411410%0–75%–370MC22122110901308%1–100%–257MAA29244234123113–54%–13–25%–171MC26161151161150–6%–1–100%–163MC31232160200151–35%–8–50%–163MC27200182111141–30%–6N/A165FC30211160160200–5%–1–100%–165FC22161140110130–19%–3–100%–1Preop, preoperative; POM, Postoperative Month; IOP, intraocular pressure; Med, Medications; Tm, Maximum recorded IOP; A, Asian; C, Caucasian; AA, African American ∆ % = Percent IOP reduction† ∆ # = Change in IOP mmHg‡ ∆ # % = Percent IOP reduction§ ∆ # = Change in number of IOP medications used Open table in a new tab Preop, preoperative; POM, Postoperative Month; IOP, intraocular pressure; Med, Medications; Tm, Maximum recorded IOP; A, Asian; C, Caucasian; AA, African American At month 12, all eyes were either an IOP or medication reduction success. A ≥20% reduction in IOP was considered a successful IOP outcome, with 40% of eyes achieving this result at month 12. A successful medication outcome, deemed a ≥1 medication reduction, was achieved in 90% of eyes at month 12. The one eye that did not achieve this result was on no medications previously, and IOP in this eye was reduced by greater than 20%. All patients completed 12 months of follow-up, and no patients required additional glaucoma intervention. Transient complications arose in 2 eyes. A visually significant microhyphema was found in 1 eye in postoperative week 1 and spontaneously resolved. A second eye experienced an IOP spike on postoperative day 1 to 48 mm Hg, which normalized with IOP medication. The same eye was found to have cystoid macular edema at month 1, which resolved with anti-inflammatory treatment by month 3. Aliendres et al. are working on a similar study of PEIOL, ECP, and KDB of 49 eyes.1Aliendres JL Villavicencio JCI Menzel CG Sánchez MR Maldonado C Chauca J. Comparison of combined glaucoma and cataract surgery: canaloplasty Ab interno and micropulse v/s ab interno trabeculectomy and endocyclophotocoagulation.Invest Ophthalmol Vis Sci. 2020; 61: 3156Google Scholar Their data are unpublished, but their abstract reports a 6-month IOP decrease from a baseline of 16.96 ± 3.66 mm Hg to 11.44 ± 2.15 mm Hg at postoperative month 6. This represents a 32.5% IOP decrease and an average IOP medication decrease of 1.2, representing a 60% change. These results were favourable compared to ours in terms of IOP reduction and similar in terms of decrease in medication use. Two studies on ECP combined with PEIOL—one by Francis et al.2Francis 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: 1313-1321Abstract Full Text Full Text PDF PubMed Scopus (56) Google Scholar and one by Siegel et al.2Francis 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: 1313-1321Abstract Full Text Full Text PDF PubMed Scopus (56) Google Scholar —are comparable. Francis et al. found a 12% IOP reduction and 73% reduction in medications at 12 months.2Francis 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: 1313-1321Abstract Full Text Full Text PDF PubMed Scopus (56) Google Scholar Siegel et al. found a 15% IOP reduction and 85% reduction in medications at 12 months.3Siegel MJ Boling WS Faridi OS et al.Combined endoscopic cyclophotocoagulation and phacoemulsification versus phacoemulsification alone in the treatment of mild to moderate glaucoma.Clin Exp Ophthalmol. 2015; 43: 531-539Crossref PubMed Scopus (49) Google Scholar Preoperative IOP measurements in both studies were comparable to ours at 18.1 ± 3.0 mm Hg and 17.2 ± 4.8 mm Hg, respectively. We can reasonably conclude that PEIOL with ECP and KDB is at least as efficacious as PEIOL and ECP out to 12 months. Studies on KDB vary, making comparison difficult. Dorairaj et al. combined KDB with PEIOL and found an average 26.2% IOP reduction and 50% reduction in medications at 12 months.4Dorairaj SK Seibold LK Radcliffe NM et al.12-month outcomes of goniotomy performed using the Kahook Dual Blade combined with cataract surgery in eyes with medically treated glaucoma.Adv Ther. 2018; 35: 1460-1469Crossref PubMed Scopus (39) Google Scholar Berdahl et al. examined KDB alone and noted an impressive 36.2% IOP reduction and 40% reduction in medications at 6 months.5Berdahl JP Gallardo MJ ElMallah MK et al.Six-month outcomes of goniotomy performed with the Kahook Dual Blade as a stand-alone glaucoma procedure.Adv Ther. 2018; 35: 2093-2102Crossref PubMed Scopus (20) Google Scholar KDB with PEIOL resulted in 57.7% and 63.5% of eyes achieving a successful IOP and medication outcome, respectively.4Dorairaj SK Seibold LK Radcliffe NM et al.12-month outcomes of goniotomy performed using the Kahook Dual Blade combined with cataract surgery in eyes with medically treated glaucoma.Adv Ther. 2018; 35: 1460-1469Crossref PubMed Scopus (39) Google Scholar KDB alone resulted in 69.8% and 67.9% of eyes achieving a successful IOP and medication outcome, respectively.5Berdahl JP Gallardo MJ ElMallah MK et al.Six-month outcomes of goniotomy performed with the Kahook Dual Blade as a stand-alone glaucoma procedure.Adv Ther. 2018; 35: 2093-2102Crossref PubMed Scopus (20) Google Scholar Our combination decreased IOP less but led to a greater reduction in medications. Our successful outcome measures at 6 months were similar to those of Berdahl et al., with a slightly higher IOP at 12 months. One might assume that adding KDB to PEIOL ECP, or ECP to PEIOL KDB, offers little additional benefit. However, there are many confounding factors. First, it is possible that our small sample size is hiding the effect of the additional procedure. Second, ECP treatment can vary greatly in treatment extent and aggressiveness of application even when applied by a single surgeon in a single day. Third, adding KDB to ECP PEIOL may increase the durability of the IOP-lowering effect. This would require longer study follow-up than the 12-month postoperative time interval of this study. Comparison is also difficult due to missing variables, potential bias, and methodologic differences. Our demographic data were similar to Berdahl et al. Demographic data from Dorairaj et al. were sparse. Both studies performed a subgroup analysis showing IOP reduction ranged greatly between lower and higher preoperative IOP groups.4Dorairaj SK Seibold LK Radcliffe NM et al.12-month outcomes of goniotomy performed using the Kahook Dual Blade combined with cataract surgery in eyes with medically treated glaucoma.Adv Ther. 2018; 35: 1460-1469Crossref PubMed Scopus (39) Google Scholar,5Berdahl JP Gallardo MJ ElMallah MK et al.Six-month outcomes of goniotomy performed with the Kahook Dual Blade as a stand-alone glaucoma procedure.Adv Ther. 2018; 35: 2093-2102Crossref PubMed Scopus (20) Google Scholar Also, both of these studies received industry funding. The decision to add or remove an IOP medication is not a prescribed function. One study might have valued a lower IOP more than decreased medication burden. It is likely that this investigator would have a more impressive IOP drop but less impressive decrease in medication use. Overall, our case series demonstrates that the combination of ECP and KDB with PEIOL is comparatively safe and offers a decrease in IOP medication use at least as great as either procedure alone with PEIOL. Our small sample size was our greatest limitation in detecting subtleties in efficacy and did not allow for subgroup analyses. Furthermore, although KDB is performed on a different anatomic structure than ECP, we performed the KDB in the same quadrant as ECP. It is possible that performing the KDB in a quadrant untreated by ECP would change results given the anatomic changes caused by the procedures. Future directions include expansion of the study size, further subgroup analysis by preoperative IOP, and ultimately randomized control studies. The authors have no proprietary or commercial interest in any materials discussed in this article.