New Options for Combined Cataract and Glaucoma Surgery

REVIEW

CURRENT OPINION New options for combined cataract and glaucoma surgery

Donald L. Budenza and Steven J. Geddeb

Purpose of review To review the current literature regarding the effectiveness and risks of new surgeries that can be combined with phacoemulsification in the management of cataract and glaucoma. Recent findings Surgical options for concurrently managing cataract and glaucoma have expanded in recent years. Endoscopic cyclophotocoagulation, trabecular micro-bypass stent, ab interno trabeculectomy, and canaloplasty may be performed in conjunction with cataract extraction to provide additional intraocular pressure (IOP) reduction. Studies evaluating these new glaucoma procedures combined with phacoemulsification generally include retrospective case series without a comparison group. Because cataract surgery alone is associated with IOP reduction, the relative contribution of the glaucoma procedure in lowering IOP cannot be determined in these studies. Randomized clinical trials are needed to better evaluate the efficacy and safety of newer glaucoma procedures in combination with cataract surgery. Summary The newer glaucoma procedures appear less effective than trabeculectomy, but they are associated with a lower risk of surgical complications. Keywords cataract surgery, glaucoma surgery, phacoemulsification

INTRODUCTION prospective [3&&] studies have shown that cataract Cataract and glaucoma frequently coexist in our surgery alone may result in a modest (2–3 mmHg) elderly patient population. It has been estimated reduction in intraocular pressure (IOP). Therefore, that 20% of cataract procedures are performed annu- determination of the relative contribution of a glau- ally in the USA in individuals with comorbid glaucoma procedure in lowering the IOP requires pro- coma and ocular hypertension. Phacoemulsification spective comparison with a control group consisting combined with trabeculectomy has historically of cataract surgery alone. Unfortunately, random- been the preferred surgical approach for concur- ized clinical trials that assess the new glaucoma rently managing cataract and glaucoma. However, procedures are generally lacking. The purpose of a growing concern about intraoperative and post- this article is to provide an evidence-based review operative complications associated with trabeculec- of the new options for combined cataract and tomy has prompted many surgeons to explore glaucoma surgery. alternative procedures. Several new glaucoma procedures have been introduced into clinical practice

which may be performed in conjunction with cat- a aract surgery [1&&]. Department of Ophthalmology, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina and bBascom Palmer Recent studies have evaluated the safety and Eye Institute, Miller School of Medicine, University of Miami, Miami, efficacy of endoscopic cyclophotocoagulation Florida, USA (ECP), trabecular micro-bypass stent (iStent), ab Correspondence to Donald L. Budenz, MD, MPH, 5151 Bioinformatics, interno trabeculectomy (Trabectome), and canalo- CB7040, Chapel Hill, NC 27517, USA. Tel: +1 919 843 0297; fax: +1 plasty combined with phacoemulsification. Most 919 966 1908; e-mail: [email protected] of these studies consist of retrospective case series Curr Opin Ophthalmol 2014, 25:141–147 that lack a control group. Retrospective [2] and DOI:10.1097/ICU.0000000000000027

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phacoemulsification has not been clearly demon- KEY POINTS strated. Most studies reporting the outcomes of phacoemulsification–ECP are retrospective case Glaucoma and elevated IOP are common in patients & & undergoing cataract surgery. series that lack a control group [4 ,5 ,6–8]. A randomized clinical trial comparing phacoemulsifi- Endoscopic cyclophotocoagulation (ECP), trabecular cation alone with phacoemulsification–ECP would micro-bypass stent (iStent), ab interno trabeculectomy help to clarify the efficacy of phacoemulsification– (Trabectome), and canaloplasty are newer glaucoma procedures that may be performed in conjunction ECP (Table 1). with phacoemulsification. A prospective randomized trial compared phacoemulsification–ECP to phacoemulsification– Because phacoemulsification can produce intraocular trabeculectomy (48% of cases received adjunctive pressure (IOP) reduction, studies evaluating the efficacy mitomycin C) in a relatively small number of of combined cataract and glaucoma procedures should include a comparison group of phacoemulsification patients (29 in each treatment group) [10]. A higher alone. success rate (IOP <19 mmHg without glaucoma medications) was observed after phacoemulsifica- The newer glaucoma procedures appear less effective tion–trabeculectomy (42%) compared with phacoe- in lowering IOP than trabeculectomy, but they are mulsification–ECP (30%) with a mean follow-up of associated with fewer surgical complications. 2 years. A retrospective study compared phacoemulsification–ECP in 626 eyes to phacoemulsification alone in 81 eyes [9]. The methodology for this investigation was not described, including the COMBINED PHACOEMULSIFICATION AND criteria used for unequal matching of eyes (approxi- ENDOSCOPIC mately 8 : 1). Mean IOP decreased by 17.6% in the CYCLOPHOTOCOAGULATION phacoemulsification–ECP group with an associated ECP is a newer method of cyclophotocoagulation 57.5% decrease in the mean number of glaucoma involving laser treatment of the ciliary processes medications, and mean IOP increased by 4.2% in the under direct visualization. ECP has been used in phacoemulsification group without a change in the the management of refractory glaucomas and mean number of glaucoma medications with an pediatric patients, but it is most commonly per- average follow-up of 3.2 years. formed in combination with phacoemulsification Most surgeons suggest that ECP results in a mild- in eyes with medically controlled or uncontrolled to-moderate decrease in IOP and medical therapy. glaucoma. IOP reduction ranging from 17.6 to 57% has been reported following phacoemulsification–ECP. These highly variable results may relate to differ- Efficacy ences in study populations, length of follow-up, and Despite the availability of ECP since the mid-1990s, treatment protocol (i.e., degrees of laser application, its benefit in reducing the IOP when combined with ECP through the bag or under the intraocular lens,

Table 1. Studies of combined phacoemulsification and endoscopic cyclophotocoagulation

Change from baseline Number Follow-up Number (%) Author (year) Treatment of eyes (months) lost to follow-up Mean IOP (%) Mean Meds (%)

Clement et al. [4&] PE–ECP 63 12 NR 23.9% Decrease 45.8% Decrease Lindfield et al. [5&] PE–ECP 58 24 17 (29%) 33.0% Decrease 5.1% Increase Lima et al. [6] PE–ECP 368 35.2 (Mean) NR 46.7% Decrease 74.3% Decrease Kahook et al. [7] PE–ECP (1 site) 15 6 8 (53%) 32.2% Decrease 21.9% Decrease PE–ECP (2 sites) 25 12 (48%) 46.9% Decrease 79.7% Decrease Berke [9] PE–ECP 626 38.4 (Mean) NR 17.6% Decrease 57.5% Decrease PE 81 4.2% Increase 0% Gayton et al. [10] PE–ECP 29 23.5 (Mean) 12 (21%) 28.8% Decrease 34.4% Decrease PE–trab 29 27.2 (Mean) 31.9% Decrease 29.2% Decrease Uram [8] PE–ECP 10 19.2 (Mean) 0 (<1 year) 23.9% Decrease 45.8% Decrease

ECP, endoscopic cyclophotocoagulation; IOP, intraocular pressure; meds, glaucoma medications; NR, not reported; PE, phacoemulsification; trab, trabeculectomy.

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ECP with or without scleral indentation, and cessa- and current information about the benefit of pha- tion or continuation of medical therapy). coemulsification–ECP is mostly uncontrolled. The long-term results of phacoemulsification– ECP are not well known, and concern exists that COMBINED PHACOEMULSIFICATION AND the IOP-lowering effect of ECP may diminish over iSTENT time [11]. A histopathologic study demonstrated The trabecular meshwork micro-bypass stent that ECP causes localized shrinkage of ciliary proc- (iStent, Glaukos, Corp., Laguna Hills, California, esses and reduction in blood flow with partial reper- USA) is a titanium implant that is inserted into fusion by 1 month [12]. It has been speculated that Schlemm’s canal through the trabecular meshwork the partial return of blood flow may lead to an internally. The implant is designed to shunt fluid increase in aqueous production with a correspond- from the anterior chamber into Schlemm’s canal, ing rise in IOP. The need to retreat an eye with ECP bypassing the trabecular meshwork. The device is after an initial effect may be explained by this placed after completion of cataract surgery, so that phenomenon. the anterior chamber is maximally deep and so that it does not get dislodged during the phacoemulsification procedure. Surgical complications The safety profile of ECP in the existing medical Efficacy literature is varied and likely relates to the glaucoma There have been several studies of cataract surgery subtype treated [13&&]. Surgical complications combined with iStent, some of which have a com- observed in a large series of 368 eyes treated with parison group of patients undergoing cataract phacoemulsification–ECP included IOP spike surgery alone. In the longest and largest prospective (14.4%), postoperative fibrin exudates in anterior randomized clinical trial of the iStent conducted by chamber (7.06%), cystoid macular edema (4.34%), Samuelson and colleagues [14,15&&], iStent com- transient hypotony (2.17%), and iris bombe´ (1.08%) bined with phacoemulsification produced IOP low- [6]. Lower rates of surgical complications have been ering similar to phacoemulsification alone at 1 year reported with micro-invasive glaucoma surgery [14]. However, IOP was controlled on 1–2 fewer (MIGS) [1&&]. Additionally, the pressure-lowering medications than before surgery [14]. At 2 years, effect of cyclodestruction cannot be reversed in the differential effect of phacoemulsification–iStent patients with hypotony-related sequelae. compared with phacoemulsification alone is more pronounced, as the IOP-lowering effect of cataract surgery diminishes [15&&]. Although the iStent only Conclusion lowered pressure by 8% in this study, the effect Limited data exist in the peer-reviewed literature on number of medications used was profound, describing the efficacy and safety of phacoemulsifi- with an over 80% reduction in medications out to cation–ECP. A randomized clinical trial comparing 24 months (Table 2). phacoemulsification–ECP to phacoemulsification Studies by Spiegel [18] and Fea [16] have shown alone is needed to better evaluate this technique, an approximately 20% reduction in IOP after a

Table 2. Studies of combined phacoemulsification and iStent

Change from baseline Number Follow-up Number (%) Author (year) Treatment of eyes (months) lost to follow-up Mean IOP (%) Mean Meds (%)

Craven et al. (2012) [15&&] PE–1 iStent 117 24 19 (16.2%) 8.1% Decrease 81.3% Decrease PE 123 22 (17.9%) 0.6% Decrease 66.7% Decrease Samuelson et al. (2011) [14] PE–1 iStent 117 12 17 (14.5%) 8.0% Decrease 86.7% Decrease PE 123 13 (10.6%) 5.0% Decrease 73.3% Decrease Fea (2010) [16] PE–1 iStent 12 15 0 17.3% Decrease 80.0% Decrease PE 24 3 (12.5%) 9.2% Decrease 31.6% Decrease Ferna´ndez-Barrientos et al. (2010) [17] PE–2 iStents 17 12 0 27.3% Decrease 100% Decrease PE 16 0 16.1% Decrease 41.7% Decrease Spiegel et al. (2009) [18] PE–1 iStent 48 12 6 (12.5%) 20.3% Decrease 75.0% Decrease

IOP, intraocular pressure; meds, glaucoma medications; PE, phacoemulsification.

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single iStent combined with cataract surgery. with cataract surgery, the Trabectome is typically Patients were also able to reduce the number of delivered prior to phacoemulsification as excellent medications by 75–100%. The study by Fea [16] also visualization is needed to perform the procedure included a comparison group of patients who under- and corneal clarity may be reduced after phacoe- went phacoemulsification alone, and this group mulsification, making visualization difficult. had a reduction in IOP of 9.2% compared with the phacoemulsification–iStent group that had a reduction in IOP of 17.3%. However, the average Efficacy number of medications was reduced by 80% in the Several studies have demonstrated that phaco- combined group vs. only 30% in the cataract surgery emulsification–Trabectome lowers IOP by about alone group. The study by Spiegel did not have a 4–7 mmHg [20–22,23&]. One of these studies [21] comparison group. included a comparison group of patients who under- Recent studies suggest that implantation of went phacoemulsification alone. Unfortunately, multiple iStents provides better IOP lowering than patients were not randomized and differed by a single iStent [17,19&]. It remains to be seen whether 6 mmHg in IOP at baseline. In this study, the the manufacturer will be able to provide more than phacoemulsification–Trabectome group had a one device per package or whether insurers or mean preoperative IOP of 22.2 mmHg, whereas patients will pay for additional devices to be the preoperative IOP in the phacoemulsification implanted. New designs of this device and similar alone group averaged 16.2 mmHg. The IOP-lower- trabecular bypass devices are in trials now that may ing effect of phacoemulsification alone is known to obviate the need to place more than one iStent. In be highly correlated with the preoperative IOP the meantime, placement of a single iStent device [3&&,14,15&&,24&&]. Specifically, patients with high with cataract surgery has little IOP advantage over preoperative IOPs may have a large IOP-lowering cataract surgery alone. effect from phacoemulsification, whereas those with a low IOP may have little to no effect. So the comparison of combined phacoemulsification– Surgical complications Trabectome to phacoemulsification alone does iStent is a relatively safe procedure. The majority not seem valid in this study. In addition, the change of complications is related to malposition of the in medical therapy in the phacoemulsification implant and stent obstruction [14,15&&,16–18]. alone group was not reported. The investigators performed a subanalysis in which they matched 10 patients from each group on baseline IOP and Conclusion compared the results. The phacoemulsification– iStent performed with cataract surgery is a safe pro- Trabectome patients averaged 25% lower IOP, and cedure, but it offers little additional IOP-lowering the phacoemulsification alone group had a 5% rise effect compared with cataract surgery alone. Its main in IOP at 12 months. A randomized clinical trial advantage appears to be in the reduction in hypo- would allow a better comparison of phacoemulsifi- tensive medication use. The pivotal randomized pro- cation–Trabectome and phacoemulsification alone spective trial comparing phacoemulsification–iStent (Table 3). to phacoemulsification alone provides the best information on the efficacy of the procedure and serves as a model for future trials of devices such as this. Second Complications and third generation designs may provide additional Transient hyphema and postoperative elevation of IOP-lowering effects. IOP are the main complications of Trabectome combined with phacoemulsification, as with Trabec- tome alone. The mechanism, extent, and duration COMBINED PHACOEMULSIFICATION AND of the IOP elevation following Trabectome are TRABECTOME unknown and unpredictable, adding some uncer- Ab interno trabeculotomy, also known as Trabec- tainty to the postoperative management of these tome (NeoMedix, Tustin, California, USA), is a new patients. procedure in which sections of the trabecular meshwork are ablated using electrocautery delivered by a probe introduced through the anterior chamber. Conclusion The amount of trabecular meshwork that is ablated There is inconclusive evidence that Trabectome varies depending on the exposure and visualization, added to phacoemulsification has better IOP-low- but typically is 3–4 clock hours. When combined ering effect compared with phacoemulsification

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Table 3. Studies of combined phacoemulsification and Trabectome

Change from baseline Number Follow-up Number (%) Author (year) Treatment of eyes (months) lost to follow-up Mean IOP (%) Mean Meds (%)

Francis (2010) [21] PE–Trabectome 114 24 47 (41%) 31.1% Decrease 41.7% Decrease PE 145 104 (71.7%) 11.7% Decrease NR Mosaed et al. (2010) [22] PE–Trabectome 290 12 24 (8%) 22.8% Decrease 33.5% Decrease Francis and Winarko (2011) [20] PE–Trabectome 89 12 4 (5%) 30.3% Decrease 43.3% Decrease Ahuja et al. (2013) [23&] PE–Trabectome 158 24 106 (67%) 22.2% Decrease 31.9% Decrease

IOP, intraocular pressure; meds, glaucoma medications; PE, phacoemulsification; NR, not reported. alone. Prospective randomized clinical trials are studies [25–27]. The remarkably similar results of needed to demonstrate this. However, the procedure these studies may be because of pooling of data from seems to lower IOP better than IOP-matched con- the same patients in all three reports. None of the trols and the complications are minimal. studies used a comparison group of phacoemulsification alone. A more recent small independent study by Matlach et al. [28&], also without a com- COMBINED PHACOEMULSIFICATION AND parison group of phacoemulsification alone CANALOPLASTY patients, found an average 55% drop in IOP after Canaloplasty is an ab externo procedure during 12 months. In the only study to date comparing which Schlemm’s canal is cannulated with a fiber phacoemulsification–canaloplasty to phacoemulsi- optic probe (iScience International, Menlo Park, fication alone, Arthur et al. [29&&] have reported a California, USA), and a suture is then introduced more profound IOP-lowering effect of the combined 3608 and tightened until the trabecular meshwork is procedure throughout 24 months, although half to put on adequate stretch to improve aqueous humor two-thirds of patients were lost to follow-up. The outflow. Ideally, high-resolution ultrasound is used study was retrospective, so there was no randomiz- to confirm that the tissues of interest are properly ation and the starting IOPs were relatively low in stretched. The procedure is technically more diffi- each group (16.2 in the phacoemulsification group cult than those previously described and has the and 18.2 in the phacoemulsification–canaloplasty additional disadvantage of causing conjunctival group). In addition, the phacoemulsification–canal- scarring, which makes subsequent glaucoma surgery oplasty group started with mean baseline IOPs that less successful and technically more difficult. An were 2 mmHg higher than in the phacoemulsifica- additional disadvantage is the expense of the equip- tion group. Although there was no statistically sig- ment that is needed to perform the operation. nificant difference in IOP at baseline or 24 months, patients in the combined group were on fewer medi- Efficacy cations and were less likely to fail by the standard Combined phacoemulsification–canaloplasty was criteria as outlined in the Tube vs. Trabeculectomy shown to lower IOP by approximately 40% in three Study [30] (Table 4).

Table 4. Studies of combined phacoemulsification and canaloplasty

Change from baseline Number Follow-up Number (%) Author (year) Treatment of eyes (months) lost to follow-up Mean IOP (%) Mean Meds (%)

Matlach et al. (2013) [28&] PE–canaloplasty 19 12 4 (21%) 55.5% Decrease 64.3% Decrease Arthur et al. (2013) [29&&] PE–canaloplasty 32 24 21 (66%) 29.1% Decrease 76.9% Decrease PE 37 20 (54%) 13.0% Decrease 7.1% Increase Lewis et al. (2011) [26] PE–canaloplasty 30 36 3 (10%) 42.1% Decrease 80% Decrease Bull et al. (2011) [27] PE–canaloplasty 16 36 3 (19%) 43.2% Decrease 66.7% Decrease Shingleton et al. (2008) [25] PE–canaloplasty 54 12 25 (53.7%) 43.9% Decrease 86.7% Decrease

IOP, intraocular pressure; meds, glaucoma medications; PE, phacoemulsification; trab, trabeculectomy.

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Complications Acknowledgements Transient hyphema, inadvertent filtering bleb, None. Descemet’s detachment, and suture erosion through the trabecular meshwork may be seen after phacoe- Conflicts of interest mulsification–canaloplasty. In addition, suture There are no conflicts of interest. placement within the canal may not be possible in approximately 15–25% of patients [25,26]. REFERENCES AND RECOMMENDED Conclusion READING Phacoemulsification–canaloplasty appears to be Papers of particular interest, published within the annual period of review, have been highlighted as: more effective at lowering IOP than phacoemulsifi- & of special interest cation alone and may be an effective and well && of outstanding interest

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