THE EFFECT OF AND COMBINED PHACO/ PROCEDURES ON THE IN OPEN-ANGLE GLAUCOMA A REVIEW OF THE LITERATURE

AUGUSTINUS CJ, ZEYEN T

ABSTRACT KEY WORDS Purpose: This review article addresses the different Canaloplasty, , Cypass, intraocular aspects that influence the choice and sequence of pressure, iStent, Hydrus, open-angle glaucoma, surgical treatment in patients with coexisting open- phacoemulsification, , Trabectome angle glaucoma and cataract. The effect of pha- coemulsification on the intraocular pressure (IOP) and on a preexisting bleb is discussed and phaco- trabeculectomy and trabeculectomy are compared. Moreover, the most recent surgical pressure lower- ing techniques in combination with phacoemulsifi- cation are reviewed: iStent, Trabectome, Hydrus, Cy- pass and Canaloplasty. Methods: Medline database was used to search for relevant, recent articles. Conclusion: A sustained IOP decrease of 1.5 mmHg can be expected after a phacoemulsification in pa- tients with open-angle glaucoma. The higher the pre- operative pressure, the greater the IOP lowering will be. A phacoemulsification on a trabeculectomized will often lead to reduced bleb function and an IOP rise of on average 2 mmHg after 12 months. Compared to a trabeculectomy, phaco-trabeculec- tomy will have a less IOP lowering effect and a high- er complication rate. iStent and Trabectome combined with phacoemul- sification can decrease the IOP with 3 to 5mmHg, with a low complication rate. The combination of Cy- pass and Hydrus with phaco-surgery may have a more significant IOP lowering effect but long term results are not yet published. Combining Canalo- plasty with phacoemulsification is a more challeng- ing surgery but if a tension suture can be placed, an IOP decrease around 10 mmHg might be expected.

Bull. Soc. belge Ophtalmol., 320, 51-66, 2012. 51 INTRODUCTION Effect of clear phacoemulsification on the IOP Within the aging population, comorbidity of of open angle glaucoma glaucoma and cataract is becoming increasing- It is well known that a phacoemulsification alone ly frequent. can result in a significant decrease of the IOP Glaucoma is the most important cause of irre- (up to 6 mmHg or more) in with angle- versible blindness worldwide. At least 70 mil- closure glaucoma (CAG) provided they have lion people are suffering from glaucoma of which less than 180° goniosynechiae (4). 10% are bilaterally blind (1). Elevated intraoc- In OAG, an IOP decrease is observed as well ular pressure (IOP) is the most important risk although to a much lesser degree. Recent stud- factor in the development of the disease, al- ies have been dedicated to quantify the long though up to 30% of the patients never exceed term decrease of the IOP in those patients. One an IOP within the normal range. Lowering the of the most important studies on this subject IOP is the only treatment option for glaucoma is the study by Shingleton et al (2006) (5). The nowadays. IOP of OAG patients, glaucoma suspects and Cataract is an age-related disease. According normal controls were compared before pha- to the WHO, cataract is the leading cause of coemulsification, after three and after five years. reversible blindness worldwide. About 1 in 6 In the OAG group, only patients with an ade- persons above the age of 40 will suffer from quate pressure control, without previous sur- cataract (2). gery and without indication for glaucoma sur- The treatment of either condition can influence gery were included. An IOP decrease of approx- the course of the other. It is widely accepted imately 1.5 mmHg was measured in all groups. that the use of glaucoma laser treatments and The decrease was significant after three years surgical glaucoma procedures can accelerate and sustained after five years (5). These re- cataract formation. Glaucoma medications could sults were similar to the ones published by Math- cause cataract progression as well (3). On the alone et al (2005): an IOP decrease of 2 mmHg other hand, phacoemulsification might influ- in primary OAG (PAOG) patients two years af- ence the intraocular pressure (IOP) in glauco- ter phaco-surgery (6). ma patients. Poleyetal(2008) focused on the effect of the This review article will address the different as- preoperative IOP on the IOP lowering effect af- pects that influence the choice and sequence ter phacoemulsification in eyes with ocular hy- of surgical treatment in patients with coexist- pertension (OHT) and normal eyes: the higher ing open-angle glaucoma (OAG) and cataract. the IOP before surgery, the more significant the The effect of phacoemulsification on the IOP postoperative IOP decrease (7). In a follow-up and on a preexisting bleb will be discussed, study, Poleyetal(2009) looked at the pres- phaco-trabeculectomy and trabeculectomy will sure lowering effect of phacoemulsification in be compared and the most recent surgical pres- glaucoma patients and found a similar out- sure lowering techniques in combination with come. However, their results were biased be- phacoemulsification will be reviewed. cause patients with CAG as well as OAG were included without subgroup analysis (8). As men- SEARCH METHOD tioned by Shrivastava et al in a review article (2010) on the same subject, more IOP fluctu- Medline database was used to search for rele- ations may occur in patients with high IOPs vant, recent articles. At the end of each para- (OHT as well as glaucoma patients) (the re- graph, appropriate key-words are mentioned. gression to the mean effect), emphasizing the To find the most recent information of novel sur- importance of acquiring enough baseline mea- gical glaucoma techniques, the websites of the surements. Regression to the mean is a statis- device manufacturers were consulted. tical phenomenon than can make natural vari- ation in repeated data look like real change. It happens when unusually high or low IOP mea-

52 surements tend to be followed by measure- The blebs were more vascularized and less prom- ments that are closer to the mean (9). inent (14). The reason why phacoemulsification results in On the other hand, bleb function also decreas- a decrease of IOP remains unclear. Two mech- es spontaneously after trabeculectomy, even anisms might play a role. First, a further open- without phacoemulsification, but then the IOP ing of the angle after removal of a thickened increase is slower and more gradual (16,17). , a mechanism well known in CAG. Sec- The Advanced Glaucoma Intervention Study ond, a stretching of the trabeculum by fibrosis (AGIS) concluded that a 1-2 mmHg IOP rise of the capsular bag. A smaller could be expected within 6 years after a trabe- may promote this mechanism. culectomy, depending on the post-trabeculec- tomy IOP in the first 18 months. If the IOP was In conclusion, a long term IOP decrease of below 14 mmHg the first 18 months after the about 1.5 mmHg is to be expected after pha- trabeculectomy, the pressure rise over time was coemulsification alone in open angle glauco- limited (17). ma. The higher the preoperative pressure, the greater the IOP lowering effect will be. KEY WORDS KEY WORDS phacoemulsification, bleb function phacoemulsification, intraocular pressure, Comparison of IOP lowering open-angle glaucoma effect between Limits used during search: Review, randomized trabeculectomy and a controlled trial (RCT), meta-analysis, articles of combined phaco- the last 10 years trabeculectomy Effect of phacoemulsification on a filtering bleb The introduction of small incision phaco-sur- gery made it much easier to combine cataract Performing a phacoemulsification on a trabe- surgery with trabeculectomy. However, several culectomized eye may lead to reduced bleb func- studies have shown that trabeculectomy alone tion, especially if the phacoemulsification is lowers the IOP significantly more than com- done within 6 months after the trabeculecto- bined phaco-trabeculectomy. my (10,11). Husain et al (2012) examined the Three studies compared the two techniques di- risk of bleb failure in relation to the time be- rectly. In 2003, Lochhead et al published a sin- tween phacoemulsification and trabeculecto- gle surgeon randomized controlled trial (RCT), my. This study concluded that the risk of bleb comparing the IOP lowering effect of phaco- failure almost doubled if the interval between trabeculectomy and trabeculectomy alone in trabeculectomy and phacoemulsification was two matched groups of chronic OAG patients less than 6 months compared to an interval of (18). The preoperative IOPs in both groups were more than 6 months (11). not mentioned but were not significantly differ- Several studies showed that bleb failure led to ent. The postoperative IOP in the trabeculec- an IOP increase of on average 2 mmHg in the tomy group was 13 ± 1.0 mmHg, with an IOP first 12 months after the phacoemulsification decrease of 11.0 ± 1.4 mmHg. In the pha- (12-15). However, according to Rebolleda et cotrabeculectomy group, the postoperative IOP al, phacoemulsification affected bleb function was 15.5 ± 1.1 mmHg, with an IOP decrease less when the IOP after trabeculectomy and be- of 6.7 ± 2.1 mmHg. This difference was sig- fore phacoemulsification was lower. The IOP in- nificant (p= 0.0017). Additionally, more com- crease was significantly lower when the IOP be- plications were seen in the phaco-trabeculec- fore phacoemulsification was below 10 mmHg. tomy group (18). Murthy et al published a sim- The IOP after phacoemulsification remained ilar RCT in 2006 but they used mitomycin-C significantly lower than before trabeculecto- (MMC) in every procedure (phaco-trabeculec- my, even if a pressure rise occurred (15). In ad- tomy as well as trabeculectomy alone), where- dition to a pressure rise, a change in bleb char- as in the Lockhead study, were acteristics was seen after phacoemulsification. never used. In the Murthy study, the postoper-

53 ative IOPs were similar in both groups, around did an additional search for articles that dis- 13.5 mmHg, but the preoperative IOPs in the cuss the results of each technique separately. trabeculectomy group was significantly higher Most papers that examined the effect of a tra- (26.1 mmHg) than the preoperative IOPs in the beculectomy alone reported a postoperative IOP phaco-trabeculectomy group (20.3 mmHg). around 13 mmHg and an IOP decrease around Looking at the absolute IOP lowering effect, tra- 10 mmHg. If antimetabolites were used post- beculectomy lowered the IOP more than the operative IOPs of less than 12 mmHg could be combined procedure, with an IOP decrease of obtained (22-24). However, as mentioned above, 10.87 ± 8.33 mmHg (41.6%) in the trabe- long-term follow-up showed a gradual decrease culectomy group, compared to 6.15 ± 7.01 in effect of the procedure (16,17). mmHg (30.3%) in the phaco-trabeculectomy Studies focusing on phaco-trabeculectomy alone, group (p = 0.003) (19). Chang et al com- generally showed a postoperative IOP around pared phaco-trabeculectomy with trabeculec- 15 mmHg and an IOP decrease of 6 to 7 mmHg. tomy, both combined with 5-fluorouracil (5- Two-site phaco-trabeculectomy didn’t result in FU) in a retrospective nonrandomized study, a lower IOP compared to one-site phaco-trab- published in 2006 (20). The preoperative IOP eculectomy. The operating time of a one-site was 23.4 ± 4.6 mmHg in the phaco-trabe- procedure however was shorter with less en- culectomy group and 25.1 ± 3.7 in the trabe- dothelial cell loss (25-28). culectomy group, the latter being significantly higher (p = 0.02). In the phaco-trabeculecto- We can conclude that trabeculectomy alone my group, an IOP decrease of 7.3 mmHg lowers the IOP more than phaco-trabeculec- (31.2%) was achieved, with a postoperative tomy, as stated in the European Glaucoma So- IOP of 16.1 ± 8.2 mmHg after one year. In the ciety guidelines (29). Apart from the lesser trabeculectomy group the IOP lowered with 11.2 amount of IOP lowering, phaco-trabeculecto- mmHg (44.6%) to a postoperative IOP of 13.9 my has more complications than phacoemul- ± 3.4 mmHg. The difference in IOP decrease sification alone (30) and combined surgery between the two groups was significant (p = prolongs the operation time. Furthermore, the 0.02). Moreover, the phaco-trabeculectomy postoperative refraction is less predictable in group needed significantly more 5-FU injec- combined surgery because of less foreseeable tions after the procedure (p = 0.008) (20). anterior chamber depth, especially early after Since phacoemulsification affects a preexist- surgery or after needling procedures. Finally, ing bleb (see previous chapter), the next step it is not advisable to preform combined sur- would be to compare the IOP lowering effect gery if only one quadrant of conjunctiva is left of phaco-trabeculectomy with the IOP lower- untouched and the target IOP is low (e.g. < ing effect of trabeculectomy followed by pha- 15 mmHg). However, a phaco-trabeculecto- coemulsification. We found one study by my is a valid option in patients who insist in Donoso et al that retrospectively compared a undergoing only one surgical procedure. In group of 18 patients that underwent a pha- those patients, it is advisable to spare one coemulsification more than 6 months after a quadrant of conjunctiva in case a second tra- trabeculectomy with a group of 22 patients that beculectomy is necessary in the future. underwent a phaco-trabeculectomy. The post- Table 1a (see attachment) gives an overview operative IOP was 12.6 ± 2.1 mmHg in the of the results of phaco-trabeculectomy. Table consecutive surgery group and 12.2 ± 2.7 2 compares the results of trabeculectomy to mmHg in the combined group. Regrettably, no phaco-trabeculectomy. preoperative IOPs from before the trabeculec- tomy were mentioned and the postoperative KEY WORDS IOPs were not compared statistically. Howev- phacotrabeculectomy, trabeculectomy, intraocular er, the success rates of both groups were not pressure significantly different (p=0.333) (21). Since only a limited amount of articles could be found that compared the two surgeries, we

54 Combination of novel IOP lowering procedures with phacoemulsification Over the last decade, there has been a lot of interest in novel trabecular surgery. These tech- niques need only a small corneal incision and are therefore easy to combine with phacoemul- sification. In general, the new procedures low- er the IOP less than a trabeculectomy (31). The different procedures can be divided in a. groups, based on the type of incision (ab inter- no versus ab externo) and on outflow mecha- nism (trabecular versus uveo-scleral) (32). We will discuss the combination of phacoemul- sification with three ab interno procedures that enhance trabecular outflow (iStent, Trabecto- me and Hydrus), with one procedure that en- hances uveo-scleral outflow (Cypass) and fi- nally with one ab externo procedure (Canalo- b. plasty). Table 1b (see attachment) gives an overview Fig. 1: of the results of iStent, Trabectome and Cana- a. iStent trabecular microbypass stent (courtesy of Glaukos Corporation), Laguna Hills, California) loplasty combined with phacoemulsification. b. Gonioscopic image showing correct placement of Table 2 (see attachment) compares the results iStent of second generation iStents (iStents inject) (Cour- of combined Phaco-Trabectome to Trabectome tesy Matt Poe) and combined Phaco-Canaloplasty to Canalo- plasty. temporal incision of a phacoemulsification, the two procedures can be combined easily. AB INTERNO PROCEDURES Most studies refer to the combination of pha- The iStent and Trabectome, both enhancing tra- coemulsification with one iStent. becular outflow, are the most extensively stud- Samuelson et al published a large RCT in 2011, ied novel procedures with an ab interno ap- funded by the manufacturer of the iStent, com- proach. Hydrus is an intracanalicular implant, paring the effect of phacoemulsification com- of which only initial IOP results are known. The bined with one iStent to phacoemulsification Cypass micro-stent is a new filtering device pro- alone in a group of more than 200 patients moting supra-choroidal drainage and uveo- (33). The mean preoperative IOP of the total scleral outflow with ongoing phase 3 trials (Com- population was 18.4 ± 3.2 mmHg. An IOP de- pass study). All the above mentioned devices crease of 1.5 ± 3.0 mmHg (8%) was achieved can be inserted through a small corneal inci- in the group with combined surgery compared sion under gonioscopic control. Because the an- to 1.0 ± 3.3 mmHg (5.4%) in the phacoemul- gle has to be visualized, only OAG patients are sification group after 12 months, which was not eligible for these types of procedures. significantly different. On the other hand, the need for postoperative IOP lowering medica- iStent tion was significantly lower in the group with The iStent (manufactured by Glaukos Corpora- combined surgery (15% of the patients) than tion, Laguna Hills, CA) is an L-shaped trabe- in the group with phacoemulsification alone cular stent made from titanium (Figure 1). It is (35% of the patients, p = 0.001) (33). Fea et to be inserted into Schlemm’s canal using a go- al published a similar but smaller RCT in 2010 nioscope and serves to bypass the trabecular (34). The mean preoperative IOP in the com- resistance and create an easier outflow of aque- bined surgery group was 17.9 ± 2.6 mmHg ous humor. Since it can be inserted through the compared to 17.3 ± 3.0 mmHg in the pha-

55 56 Table 1a: Results of combined procedures

Authors (year) N FU Intervention type Study type Comment (m) Pre-op IOP Post-op IOP IOP Pre-op med Post-op med Complications (% (mmHg) (mmHg) decrease (n) (n) patients) (mmHg) (%) Phaco-Trabeculectomy Lochhead et al (2003) 88 29 n/a 15.5 ± 1.1 6.7 ± 2.1 n/a n/a Sulcus IOL + Retrospective One-site 18 anterior VTX without Choroidal effusion MMC/5FU Murthy et al (2006) 19 190 24 20.3 13.98 ± 4.7 6.15 ± 7.01 2.80 1.05 Retrospective One-site with MMC Chang et al (2006) 20 92 12 23.4 ± 4.6 16.1 ± 8.2 7.3 (31.2%) 1.8 ± 0.6 0.4 ± 0.8 Hypotony Retrospective One-site with 5FU Bleb leak Donoso et al (2000) 21 22 28 19.8 ± 2.3 12.2 ± 2.7 7.6 (38.4%) n/a n/a No bleb leaks, Retrospective One-site hypotony or with 5FU endophthalmitis Francis et al (2011) 43 23 12 23.0 ± 10.7 11.0 ± 5.7 12 (44%) 3.2 0.6 Hypotony (17) Prospective Control group Choroidal unrandomized = detachment (9) controlled phaco- trabectome One-site with MMC Rao et al (2011) 26 72 60 20.3 ± 7.2 15.5 ± 3.5 5.5 ± 7.3 1.6 ± 0.6 0.6 ± 0.8 Posterior capsular Retrospective One-site (27%) rent (3) Bleb leak without (1) MMC/5FU Endophthalmitis (1) Jin et al (2007) 27 60 30 23.1 ± 7.7 14.9 ± 4.6 8.2 (32%) 1.63 ± 0.69 0.23 ± 0.50 Blood reflux (5) Retrospective Two-site Hypotony (5) with MMC Choroidal No detachment (2) Bleb hemorrhage (3) Bleb leak (2) Gdih et al (2011) 25 24 n/a n/a 7.17 n/a n/a n/a Meta-analysis One-site 7 studies 6.56 Two-site Buys et al (2008) 28 78 24 17.6 12.5 5.1 (28.9%) 3.0 0.2 Blood reflux Prospective One-site + comparison MMC One-site vs Two-site 17.6 12.9 4.7 (26.7%) 3.0 0.4 Low endothelial Two-site + cell count, Blood MMC reflux

5-FU: 5-Fluorouracil; FU: follow-up time (months); MMC: mitomycine C; Pre-op: preoperatively; Post-op postoperatively; RCT: randomized controlled trial; VTX: Table 1b: Results of combined procedures

Authors (year) N FU Intervention type Study type Comment (m) Pre-op IOP Post-op IOP IOP Pre-op med Post-op med Complications (% (mmHg) (mmHg) decrease (n) (n) patients) (mmHg) (%) Phaco + iStent Samuelson et al (2011) 106 12 18,4 ± 3,2 n/a 1,5 ± 3,0 1.5 ± 0.6 0.2 ± 0.6 Stent obstruction RCT 33 (4) malpositioning (3) Fea et al (2010) 34 12 15 17.9±2.6 14.8±1.2 3.2 ± 3.0 2.0 ± 0.9 0.4 ± 0.7 Malpositioning RCT (18%) (17) Spiegel et al (2009) 35 48 12 21.5 16.9 4,5 ± 4,54 1.6 ± 0.8 0.4 Stent obstruction Prospective (21%) (15) uncontrolled malpositioning (6) Arriola-Villalobos et al (2012) 19 62 19.42 ± 16.26 3.16 ± 3.9 1.32 ± 0.5 1.15 ± 0.5 IOP spikes (21) Prospective 36 1.89 (16%) uncontrolled Belovay et al (2010) 37 52 12 18.7 ± 4.4 13.4 ± 3.6 5.3 (28,3%) 2.8 ± 1.0 0.5 ± 0.9 Stent obstruction Prospective Multiple uncontrolled iStents Phaco + Trabectome Francis et al (2008) 39 304 12 20.0 ± 6.3 15.5 ± 2.9 4.5 (22,5%) 2.65 ± 1.13 1.44 ± 1.29 Blood reflux (78) Prospective uncontrolled Francis (2010) 40 114 24 22.2 ± 5.9 15.3 ± 3.5 6.9 (28%) n/a n/a n/a Prospective unrandomized controlled Francis et al (2011) 43 89 12 22.1 ± 5.5 15.4 ± 3.1 6.7 (30.3%) 2.3 1.3 IOP spike (4) Prospective Control group Blood reflux not unrandomized = mentioned controlled phaco- trabecu- lectomy Minckler et al (2008) 366 12 20.0 ± 6.2 15.9 ± 3.3 4.1 (18%) 2.93 ± 1.29 1.5 ± 1.36 IOP spike (5.8) Retrospective 41 Blood reflux (78) Phaco + Canaloplasty Lewis et al (2011) 49 36 36 23.5 ± 5.2 13.6 ± 3.6 9.9 (42.1%) 1.5 ± 1.0 0.3 ± 0.5 Blood reflux Prospective results IOP spike uncontrolled patients with Descemet suture desinsertion 83.3% successful suture placement Bull et al (2011) 48 16 36 24.3 ± 6.0 13.8 ± 3.2 10.5 (43.2%) 1.5±1.2 0.5±0.7 Blood reflux Prospective IOP spike uncontrolled Descemet desinsertion Shingleton et al (2008) 54 12 24.4 ± 6.1 13.7 ± 4.4 10.7 (44%) 1.5 ± 1.0 0.2 ± 0.4 Blood reflux Prospective 57 47 Descemet uncontrolled desinsertion 58 Table 2: Results of combined versus single procedures

Authors N FU Combined intervention Glaucoma intervention Complications Study type (year) Pre-op Post-op IOP Pre-op Post-op Pre-op Post-op IOP Pre-op Post-op IOP IOP decrease med (n) med (n) IOP IOP decrease med (n) med (n) (mmHg) (mmHg) (mmHg) (mmHg) (mmHg) (mmHg) (%) (%) Phaco + Trabectome Trabectome Minckler et al (2008) 1127 12 20.0 ± 6.2 15.9 ± 3.3 4.1 2.93±1.29 1.5±1.36 25.7±7.7 16.1±3.0 9.6 2.93 ± 1.29 1.5 ± 1.27 IOP spike Retrospective 40 (18%) (37%) (5.8%) Blood reflux (78%) Phaco + Canaloplasty Canaloplasty Bulletal (2011) 109 36 24.3 ± 6.0 13.8 ± 3.2 10.5 1.5±1.2 0.5±0.7 23.0 ± 4.3 15.1 ± 3.1 7.9 1.9 ± 0.7 0.9 ± 0.9 Blood reflux Prospective 47 (43.2%) (34.3%) (18.3%) uncontrolled IOP spike (7.3%) Descemet desinsertion (3.7%) Lewis et al (2011) 157 36 23.5 ± 5.2 13.6 ± 3.6 9.9 1.5 ± 1.0 0.3 ± 0.5 23.5 ± 4.5 15.5 ± 3.5 8 (34%) 1.9 ± 0.8 0.9 ± 0.9 Blood reflux Prospective 48 (42.1%) (22.3%) uncontrolled IOP spike (6.4%) Descemet desinsertion (3.2%) Phaco + Trabeculectomy Trabeculectomy Lochhead et al (2003) 88 29 n/a 15.5 ± 1.1 6.7 ± 2.1 n/a n/a n/a 13 ± 1.0 11.0 ± 1.4 n/a n/a More in the Retrospective 17 combination group Murthy et al (2006) 190 24 20.3 13.98 ± 4.74 6.15 ± 7.01 2.80 1.05 26.1 13.56 ±10.87 ± 8.33 2.86 1.16 Hypotony, Retrospective 18 4.92 blood reflux, IOP spike Chang et al (2006) 92 12 23.4 ± 4.6 16.1 ± 8.2 7.3 1.8 ± 0.6 0.4 ± 0.8 25.1 ± 3.7 13.9 ± 3.4 11.2 1.9 ± 0.5 0.3 ± 0.5 Hypotony, Retrospective 19 (31.2%) (44.6%) endophthal- mitis, bleb leak

FU: follow-up time (months); Med: number of glaucoma medications; Pre-op: preoperatively; Post-op: postoperatively coemulsification group. An IOP decrease of 3.2 crease. The iStent may not produce enough ± 3.0 mmHg (17.8%) was achieved in the IOP decrease to stop medications in severe group with combined surgery compared to 1.6 glaucoma but it can generate a long-term de- ± 3.2 mmHg (9.2%) in the phacoemulsifica- crease of the IOP, greater than a phacoemul- tion group, after 15 months. The postopera- sification alone and a significant reduction of tive IOP in the combined group was significant- the number of glaucoma medication needed. ly lower than the postoperative IOP in the con- Combined phacoemulsification and iStent is a trol group (p = 0.031). Concerning the post- safe procedure. The most frequent reported operative need for glaucoma medication, only problems are malpositioning and stent obstruc- 33% of the patients in the combined group tion, with occasionally a need for reinterven- needed medication to reach a pre-set target IOP, tion. Early IOP spikes occured but resolved compared to 76% of the patients in the con- spontaneously (34). No major complications trol group (34). Spiegel et al did an uncon- have been described until now (32,34-36). trolled prospective study in 2009 in a group of patients that underwent a phacoemulsification KEY WORDS combined with one iStent (35). The pre-oper- ative IOP was 21.5 mmHg and an IOP decrease iStent, phacoemulsification of 4.5 ± 4.54 mmHg (21%) was achieved af- ter one year. The percentage of patients need- Trabectome ing postoperative glaucoma medication to main- The Trabectome (manufactured by Neomedix tain an IOP below 21 mmHg after 12 months Inc., Tustin, CA) is a device designed to excise was 30.9%, while before the procedure every and cauterize the inner wall of the trabeculum patient used at least one type of medication ab interno (also called ‘ab interno trabeculec- (35). The long-term results of iStent implanta- tomy’). The purpose is to lower the IOP by en- tion combined with phacoemulsification were hancing trabecular outflow without external fil- studied prospectively but uncontrolled by Arri- tration (38). ola-Villalobos et al (2012) (36). Nineteen pa- The Trabectome (Figure 2) is to be inserted into tients, with a mean preoperative IOP of 19.42 Schlemm’s canal with the aid of a gonioscope. ± 1.89 mmHg with medication were followed When activated, it ablates and removes a strip for five years. An IOP decrease of 3.16 ± 3.9 of the and the inner wall mmHg (16.33%) was achieved, which was sig- of the Schlemm canal over a 40° arc (38). The nificant (p = 0.0014). As in the study of Spie- Trabectome can be inserted through a corneal gel et al, all patients used one or more types of incision, making it relatively easy to combine medication before the surgery. After the sur- with phacoemulsification. gery, only 57.9% needed medication to main- A few prospective studies have been performed tain an IOP below 21 mmHg (36). Belovay et to examine the IOP lowering effect and the com- al examined prospectively the IOP lowering ef- plications of combined ab interno trabeculec- fect of multiple iStents, with a mean of 2.7 ± tomy with phacoemulsification, called com- 0.7 stents per patient, combined with pha- bined phaco-Trabectome. Francis et al pub- coemulsification in 52 patients (37). The pre- lished in 2008 the effect of the preoperative operative IOP was 18.7 ± 4.4 mmHg and an IOP on the IOP decrease after combined pha- IOP decrease of 5.3 mmHg (28.3%) was achieved after one year. This IOP decrease seems greater than the decrease after implantation of one iStent, but no comparative study has yet been made (37).

In conclusion, the implantation of an iStent during phacoemulsification results in a signif- icant IOP decrease of 3 to 4 mmHg but IOPs below 15 mmHg are seldom reached. Multi- Fig. 2: Trabectome (courtesy of Neomedix Inc., Tustin, ple iStents may generate a greater IOP de- California)

59 co-Trabectome in over 300 patients (39). If the preoperative IOP was 22.1 ± 5.5 mmHg in the preoperative IOP was <20 mmHg, the IOP de- combined phaco-Trabectome group compared crease was non-significant after one year; in the to 23.0 ± 10.7 mmHg in the phaco-trabe- group of patients with a preoperative IOP be- culectomy group. An IOP decrease of 6.7 mmHg tween 20 and 25 mmHg, the IOP decreased (27%) was achieved in the combined phaco- with 28.1% and in the group of patients with Trabectome group compared to 12 mmHg (44%) a preoperative IOP >25 mmHg, the IOP de- in the phaco-trabeculectomy group after one creased with 44.8%. On average, the preoper- year. This difference was significant (p<0.01). ative IOP was 20.0 ± 6.3 mmHg and an IOP If we look at the complications, the only com- decrease of 4.5 mmHg (22.5%) was obtained plication seen in the phaco-Trabectome group after one year. The only complication frequent- was an early IOP spike, in 4% of the patients. ly seen was postoperative blood reflux that re- In the phaco-trabeculectomy group, complica- solved spontaneously (39). In 2010, Francis tions were more frequent and more severe (43). published a prospective, non-randomized, con- It is important to note that all the above men- trolled trial, comparing combined phaco-Tra- tioned studies were sponsored by the manu- bectome with phacoemulsification alone (40). facturer (NeoMedixt). The mean preoperative IOP in the combined The effect of a failed Trabectome on a future group was 22.2 ± 5.9 mmHg and an IOP de- trabeculectomy in a group of POAG patients has crease of 6.9 mmHg (28%) was achieved af- been published by Jea et al in 2012 (44). The ter two years. In the phacoemulsification group, study group of 34 patients underwent a trabe- the preoperative IOP was lower (16.2 ± 4.2 culectomy after a failed Trabectome procedure mmHg) because no glaucoma patients were in- and a control group of 42 patients underwent cluded. Not surprisingly, the IOP decrease was a primary trabeculectomy. The preoperative IOP limited to 1.9 mmHg (11.7%) after two years. was 27.6 ± 11.8 mm Hg in the study group The difference in population is an important compared to 29.2 ± 11.4 mmHg in the con- bias in this study and makes the comparison trol group. An IOP decrease of 17 mmHg not meaningful (40). (61.5%) was achieved in the study group com- A retrospective, uncontrolled study was done pared to 18.2 mmHg (62.3%) in the control by Minckler et al in 2008 in a large group of group after two years, which was not signifi- patients (n=1127) to examine the effect of Tra- cantly different. The same rate of complica- bectome (41). In a subgroup of 366 patients, tions was seen in both groups. This study con- a combined phaco-Trabectome was performed. cluded that a previous Trabectome procedure The preoperative IOP in the combined phaco- was not associated with a higher failure rate of Trabectome was 20.0 ± 6.2 mmHg compared trabeculectomy (44). to 25.7 ± 7.7 mmHg in the Trabectome only group. An IOP decrease of 4.1 mmHg (18%) We can conclude that combined phaco-Tra- was achieved in the combined phaco-Trabec- bectome can give an IOP decrease of around tome group compared to 9.6 mmHg (37%) in 5 mmHg, depending on the preoperative IOP, the Trabectome only group after one year. The but IOPs <15 mmHg are seldom reached. The difference was remarkable yet possibly caused procedure is safe with minimal complications by the higher preoperative IOP in the Trabec- and blood reflux should be considered normal tome only group. Regrettably, no statistical com- after a Trabectome procedure. It is safer than parison was made. The complications that oc- a trabeculectomy and has no adverse effect on curred were early IOP spikes in 5.8% of the pa- a subsequent trabeculectomy. tients and blood reflux in 78% of the patients, disappearing spontaneously (41). Since blood KEY WORDS reflux resolving spontaneously is seen in the Trabectome, phacoemulsification majority of the patients after a Trabectome pro- cedure, it could be considered physiological Hydrus (42). The comparison between combined pha- Hydrus (manufactured by Ivantis Inc., Irvine, co-Trabectome and a phaco-trabeculectomy was CA) is a new Schlemm’s canal scaffold with published by Francis et al in 2011 (43). The three posterior windows (Figure 3). It can be

60 OAG (Figure 4). The purpose of the stent is to a. promote uveo-scleral outflow by draining the aqueous fluid from the anterior chamber into the suprachoroidal space. The micro-stent is in- troduced gonioscopically just below the scleral spur into the supraciliary space. (31). The Compass study is a phase III clinical study b. evaluating the results of this new micro-stent.

Craven et al published the initial results of a prospective case study in a poster presented at the American Academy of Ophtalmology (AAO) in 2011 (46). This study showed the efficacy and safety of the Cypass combined with pha- coemulsification. The IOP analysis only includ- ed a subgroup of 34 patients with a mean pre- operative IOP of 25.6 mmHg. The postopera- tive IOP was 15.5 mmHg, the IOP decrease 10.1 mmHg (36%) after 6 months. This IOP decrease is impressive, compared to the other novel techniques but the preoperative IOP in this subgroup was high as well. No severe com- plications were encountered (46). Fig. 3: Hydrus a. Hydrus Schematic (Courtesy of Ivantis Inc., Irvine, California) b. Gonioscopic image showing correct placement of Hydrus (Courtesy I.K. Ahmed, MD University of Toronto) inserted through a small corneal incision and can be used in combination with phacoemul- sification. Tetz reported in 2011 the three month results of a prospective uncontrolled study of 98 glau- coma patients receiving a Hydrus implant. A subgroup of 44 patients was treated with a combination of phacoemulsification and a Hy- drus implant. The preoperative IOP of the com- bined group was 21.4 ± 4.8 mmHg, the post- operative IOP after three months 15.4 ± 4.4 mmHg, with an IOP decrease of 6 mmHg (28%). The complications seen were blood reflux (15%) and iritis (4%) (45). This initial analysis looks promising but long- term results are necessary before drawing any conclusions.

Cypass Cypass (manufactured by Transcend Medical Inc., Menlo Park, CA) is a device implanted at Fig. 4: Cypass (Courtesy of Transcend Medical, Menlo Park, the time of for patients with California)

61 As with the Hydrus, RCT’s with long follow-up will be necessary before drawing con- clusions about the safety and efficacy.

AB EXTERNO PROCEDURES

Canaloplasty Canaloplasty (manufactured by iScience Interventional Corp., Menlo Park, CA) is a technique in which Schlemm’s canal is circum- ferentially catheterized and dilated, using a flexible mi- crocatheter, to improve tra- becular outflow (without bleb formation). The microcathe- Fig. 5: Canaloplasty (Courtesy of iScience Interventional Corp., Menlo Park, Cali- ter travels 360° through fornia) Schlemm’s canal after which a tension suture is put in place to distend the bined group was greater than in the group of trabecular meshwork further (Figure 5). To ac- patients with canaloplasty alone, although not cess Schlemm’s canal, a non-penetrating scler- significantly (p = 0.22). The percentage of pa- al flap is made as in non-perforating deep tients with medication need changed from sclerectomy. It can be combined with pha- 81.2% preoperatively to 38.5% three years coemulsification. postoperatively. The complications that were seen were blood reflux, IOP spikes and Descem- Shingleton et al published a prospective un- et desinsertion. No bleb formation or suture ero- controlled study in 2008 to examine the re- sion was seen (48). Lewis et al did a similar sults of canaloplasty combined with phacoemul- uncontrolled study to investigate the long-term sification (47). The complete canalization of IOP decrease after canaloplasty (49). Canali- Schlemm’s canal with the probe was success- zation was successful in all patients and the ful in 81% of the procedures and tension su- placing of tension sutures was possible in 84.7% tures could be placed in 74%. The mean pre- of the patients. In a subgroup of 30 patients operative IOP of the 54 patients was 24.4 ± with a combined phaco-canaloplasty and suc- 6.1 mmHg and a significant IOP decrease of cessful placement of the sutures the preoper- 10.7 mmHg (44%) was achieved after one year. ative IOP was 23.5 ± 5.2 mmHg and an IOP The complications that occurred were blood re- decrease of 9.9 mmHg (42.1%) was achieved flux in three eyes and a Descemet membrane after three years. In the total population, 92.4% desinsertion in one eye (47). Bull et al con- of the patients used antiglaucoma medication ducted a prospective uncontrolled study to ex- before the procedure. In the phaco-canaloplas- amine the long-term effect of canaloplasty (48). ty group only 29.6% of the patients needed Canalization was successful in all patients (109) medication to achieve an IOP below 18 mmHg and the placing of tension sutures was possi- after three years. The complications that oc- ble in 90% of the patients. A small subgroup curred in this study were similar to the ones that of 16 patients underwent canaloplasty com- occurred in the study of Bulletalwith the ex- bined with phacoemulsification and was ception that in this study erosion of the suture analysed separately. The preoperative IOP of in the anterior chamber was seen in two pa- this group was 24.3 ± 6.0 mmHg and an IOP tients (49). decrease of 10.5 mmHg (43.2%) was achieved after three years. The IOP decrease in the com-

62 In conclusion, canaloplasty combined with pha- use of antimetabolites. If the patient insists coemulsification can result in an IOP decrease on a single surgical procedure, phaco-trab- of around 10 mmHg, which is more than the eculectomy is an option, always leaving one iStent or Trabectome combined with pha- quadrant of conjunctiva intact for a possible coemulsification can achieve. Postoperative future trabeculectomy. Combined phaco-tra- IOPs below 15 mmHg are possible. But the beculectomy should be avoided when there procedure is more challenging to perform and is only one quadrant of pristine conjunctiva involves incising the conjunctiva and the , left. There is no evidence to support a gen- making this zone unusable for future filtering eralized switch from sequential to combined surgery (50). In around 10% of the cases, no phaco-trabeculectomy (29). suture placement was possible because the When staging the surgeries, it is preferable canalization was incomplete. But even with- to perform phacoemulsification first and wait out the tension sutures, the IOP decrease was minimum 6 months for a trabeculectomy, if significant (48). Although the IOP can be low- still necessary. Trabeculectomy should be per- er than after the other novel glaucoma surger- formed first if visual function is threatened ies, the operative risks are also greater, espe- by glaucoma (e.g. elevated IOP or advanced cially during the surgeon’s learning curve. optic disc cupping with visual field defects close to fixation). Key words • Novel ab interno glaucoma procedures can canaloplasty, phacoemulsification easily be combined with small incision pha- coemulsification. CONCLUSIONS iStent and Trabectome combined with pha- coemulsification can decrease the IOP with Within the aging population, coexistence of cat- 3 to 5 mmHg. This can be enough to control aract and open angle glaucoma is widespread the pressure in some patients and to reduce and can be a real challenge in daily ophthal- the need for postoperative medication. Com- mology practice. Deciding on the timing for in- bined phacoemulsification with an iStent or tervention as well as making the right choice Trabectome will probably not suffice to treat of treatment sequence is not always easy. A re- normal tension or advanced glaucoma. Since view of the literature however on the subject of the combination with phacoemulsification is the expected IOP lowering effect of phacoemul- easy and the IOP lowering effect limited, the sification or combined phaco/glaucoma sur- use of iStent and Trabectome will probably gery in open angle glaucoma, did reveal some prove to be greatest in the combination set- guidelines. ting. The combination of Cypass and Hydrus with • A long-term IOP decrease of about 1.5 mmHg phaco-surgery may have a more significant can be expected after phacoemulsification in IOP lowering effect but long term results are open angle glaucoma. The higher the preop- not yet published. erative IOP, the greater the IOP lowering ef- Canaloplasty can be combined with pha- fect will be. coemulsification as well but is a more chal- lenging surgery, needing a separate conjunc- • A phacoemulsification on a trabeculecto- tival and scleral dissection. However, if a ten- mized eye will often lead to reduced bleb sion suture can be placed, a considerable IOP function and an IOP rise of on average 2 decrease (around 10mmHg) might be ex- mmHg after 12 months. pected.

• Compared to a trabeculectomy, phaco-trab- More RCT’s, conducted independently from the eculectomy will have a less IOP lowering ef- manufactures, and comparing combined pha- fect and a higher complication rate. An IOP coemulsification + novel procedures with pha- target of 15 mmHg or less will be difficult to co-trabeculectomy or trabeculectomy alone are reach with combined surgery, even with the necessary to assess the long-term safety and

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65 (47) Shingleton B, Tetz M, Korben N − Circumfe- rential viscodilation and tensioning of Schlemm rential viscodilation and tensioning of Schlemm canal using a microcatheter to treat open-ang- canal (canaloplasty) with temporal clear cor- le glaucoma. J Cataract Refract Surg. 2011; neal phacoemulsification cataract surgery for 37(4):682-90 open-angle glaucoma and visually significant (50) Minckler DS, Hill RA − Use of novel devices cataract: one-year results. J Cataract Refract for control of intraocular pressure. Exp Eye Res. Surg. 2008; 34(3):433-40 2009; 88(4):792-81 (48) Bull H, Von Wolff K, Körber N, Tetz M − Three- year canaloplasty outcomes for the treatment of open-angle glaucoma: European study re- zzzzzz sults. Graefes Arch Clin Exp Ophthalmol. 2011; Adress for correspondence: 249(10):1537-45 Cilia Augustinus (49) Lewis RA, Von Wolff K, Tetz M, Koerber N, Guido Gezellelaan 52 Kearney JR, Shingleton BJ, Samuelson TW − BE - 2870 Puurs Canaloplasty: Three-year results of circumfe- [email protected]

66