GUEST EDITORIAL
Microinvasive glaucoma surgerydComing of age Surgeons who specialize in glaucoma have a unique place within the ophthalmic community. Motivated, some believe peculiarly, by a fascination with an enigmatic disease with no cure, young and enthusiastic glaucoma specialists begin their career confident that the skills acquired during fellowship will adequately equip them as safe-keepers of their patients' visual function. While true in most cases, glaucoma specialists quickly become pragmatists, their surgical bravado tempered by inevitable complications and limitations of traditional glaucoma surgical offerings. Although the time-honored trabeculectomy and tube shunt effectively lower intraocular pressure (IOP), most would concede that these procedures lack adequate safety to be performed as an alternative to medications early in the disease. A seemingly successful filtration procedure can turn nightmarish 5 to 10 years later with a late bleb leak, hypotony, or worse, bleb-related endophthalmitis. Perhaps no statistic bears this out better than the “return to operating room to manage complications” data in the landmark Tube Versus Trabeculectomy Shunt (TVT) trial. The reoperation rate for complications at 1, 3, and 5 years was 5%, 9%, and 18%, respectively, for trabeculectomy and 7%, 14%, and 22%, respectively, for tube surgery.1–3 Few other surgical procedures generate complications years after the original intervention. Further, these late complications are directly attributable to the surgery rather than the disease process itself. One consequence of the high morbidity inherent to traditional glaucoma surgical procedures has been that medications remain the mainstay of therapy until the disease becomes advanced, despite compliance concerns and adverse effects on the ocular surface. Simply stated, for decades we have had a gaping hole in our therapeutic armamentarium for openangle glaucoma. At one end of the spectrum, we have medications and laser trabeculoplasty, which are modestly effective and very safe. On the other end of the spectrum, we have trabeculectomy and tube shunts, which are highly efficacious but far from safe. The safety gap between medications and lasers on one hand and trabeculectomy and tubes on the other hand has been vast, wide, and persistent. Fortunately, with microinvasive glaucoma surgery (MIGS), that gap is starting to close, good news for the largest proportion of glaucoma patients, those with mild to moderate disease. I performed my first iStent (Glaukos) procedure 8 years ago as an investigator in the first ever Q 2014 ASCRS and ESCRS Published by Elsevier Inc.
U.S. Food and Drug Administration (FDA) premarket approval (PMA) study for a glaucoma device. Yet, it has been less than 2 years since the FDA approved the device for ab interno placement into Schlemm canal for the treatment of mild to moderate glaucoma. Although many remain skeptical that iStent provides enough IOP lowering to meaningfully change the landscape of surgical glaucoma therapy, I believe the stent is the first step in a disruptive reorganization of surgical glaucoma procedures. Admittedly, if the MIGS revolution fails to advance beyond where we are today, it will be a disappointment. More likely, however, MIGS is a game changer that is here to stay. While all concerned would welcome better efficacy with MIGS procedures, few would find fault in the safety data. In stark contrast to the TVT complication rate cited above, adverse events and visual acuity outcomes after phacoemulsification combined with iStent in the U.S. PMA trial were impeccable and not measurably different from those with phacoemulsification alone.4 That an incisional glaucoma operation can be combined with cataract surgery with virtually no measurable increase in adverse events is game changing, period. As glaucoma surgeons, I believe we have become too accepting of complications that “come with the territory.” In fact, vision-threatening complications are simply too common and their occurrence far too unpredictable to subject our patients with mild to moderate glaucoma to the risk of filtration surgery or tube surgery. On the other hand, filtration surgery remains very well suited to patients at high risk for severe vision loss. As surgeons, we must learn to match the risk of the disease process with the risk of the specific surgical modality we offer each patient. The FDA approval for iStent has breathed life into the MIGS movement of alternative glaucoma procedures previously limited to endoscopic cyclophotocoagulation, trabectome, and canaloplasty. The current labeling for iStent is for placement of a single stent at the time of cataract surgery. Belovay et al.5 have reported that multiple stents may result in greater IOP reduction than a single stent. While this is a very promising strategy, I would encourage potential iStent surgeons to get started by placing a single stent, and only when the technique of placing a single stent is mastered consider placing multiple stents. Placing more than 1 stent may be commonplace in the future but remains off label for the time being, and proper disclosure and financial considerations must be addressed. Additional ab interno MIGS 0886-3350/$ - see front matter http://dx.doi.org/10.1016/j.jcrs.2014.06.024
1253
1254
MICROINVASIVE GLAUCOMA SURGERY: GUEST EDITORIAL
technologies are in development including the iStent Inject (second-generation iStent) and the Ivantis Hydrus, an 8.0 mm canal stenting and tensioning device, both in U.S. clinical trials. The obvious advantage of a longer stent is that more collector channels can be accessed, further enhancing outflow. Additionally, tensioning of the meshwork may improve trabecular outflow in regions beyond the inlet that traverses the trabecular meshwork. Finally, supraciliary implants such as the Transcend Cypass or Glaukos iStent Supra offer a subscleral outflow strategy that can be used in conditions such as angle closure or when canalicular procedures fail to adequately lower IOP. Ab interno placement of anterior chamber to subconjunctival devices (AqueSys Xen) are also in trials and show early promise for a more efficient and efficacious glaucoma filtration procedure. While supraciliary and subconjunctival options benefit from lower inherent resistance in their respective outflow reservoirs, they must prove safe given the lack of the episcleral venous backstop that eliminates the risk for hypotony with canal-based procedures. Finally, ab interno trabeculectomy, ie, trabectome, and endoscopic cyclophotocoagulation continue to have an important role in the management of early to moderate glaucoma and many surgeons use these technologies as a safe alternative to transscleral filtration procedures. As IKE Ahmed so beautifully outlined earlier this year,A I strongly believe that the MIGS revolution is disruptive and has forever changed the surgical management of glaucoma. Patients and surgeons alike stand to benefit greatly from the intense research and
development invested in the surgical management of glaucoma over the last decade. It is only the beginning, and the best is yet to come. Thomas W. Samuelson, MD REFERENCES 1. Gedde SJ, Herndon LW, Brandt JD, Budenz DL, Feuer WJ, Schiffman JC; the Tube Versus Trabeculectomy Study Group. Surgical complications in the Tube Versus Trabeculectomy Study during the first year of follow-up. Am J Ophthalmol 2007; 143:23–31 2. Gedde SJ, Schiffman JC, Feuer WJ, Herndon LW, Brandt JD, Budenz DL; on behalf of the Tube Versus Trabeculectomy Study Group. Three-year follow-up of the Tube Versus Trabeculectomy Study. Am J Ophthalmol 2009; 148:670–684 3. Gedde SJ, Herndon LW, Brandt JD, Budenz DL, Feuer WJ, Schiffman JC; on behalf of the Tube Versus Trabeculectomy Study Group. Postoperative complications in the Tube Versus Trabeculectomy (TVT) study during five years of follow-up. Am J Ophthalmol 2012; 153:804–814. Available at: http:// www.ncbi.nlm.nih.gov/pmc/articles/PMC3653167/pdf/nihms380 174.pdf. Accessed June 19, 2014 4. Samuelson TW, Katz LJ, Wells JM, Duh Y-J, Giamporcaro JE; for the US iStent Study Group. Randomized evaluation of the trabecular micro-bypass stent with phacoemulsification in patients with glaucoma and cataract. Ophthalmology 2011; 118:459–467 5. Belovay GW, Naqi A, Chan BJ, Rateb M, Ahmed K II. Using multiple trabecular micro-bypass stents in cataract patients to treat openangle glaucoma. J Cataract Refract Surg 2012; 38:1911–1917
OTHER CITED MATERIAL A. Ahmed IIK, “Microinvasive Glaucoma Surgery: An Idea Whose Time Has Come,” the 2014 Binkhorst lecture presented at the ASCRS Symposium on Cataract, IOL and Refractive Surgery, Boston, Massachusetts, April 2014.
J CATARACT REFRACT SURG - VOL 40, AUGUST 2014
Microinvasive glaucoma surgerydComing of age Surgeons who specialize in glaucoma have a unique place within the ophthalmic community. Motivated, some believe peculiarly, by a fascination with an enigmatic disease with no cure, young and enthusiastic glaucoma specialists begin their career confident that the skills acquired during fellowship will adequately equip them as safe-keepers of their patients' visual function. While true in most cases, glaucoma specialists quickly become pragmatists, their surgical bravado tempered by inevitable complications and limitations of traditional glaucoma surgical offerings. Although the time-honored trabeculectomy and tube shunt effectively lower intraocular pressure (IOP), most would concede that these procedures lack adequate safety to be performed as an alternative to medications early in the disease. A seemingly successful filtration procedure can turn nightmarish 5 to 10 years later with a late bleb leak, hypotony, or worse, bleb-related endophthalmitis. Perhaps no statistic bears this out better than the “return to operating room to manage complications” data in the landmark Tube Versus Trabeculectomy Shunt (TVT) trial. The reoperation rate for complications at 1, 3, and 5 years was 5%, 9%, and 18%, respectively, for trabeculectomy and 7%, 14%, and 22%, respectively, for tube surgery.1–3 Few other surgical procedures generate complications years after the original intervention. Further, these late complications are directly attributable to the surgery rather than the disease process itself. One consequence of the high morbidity inherent to traditional glaucoma surgical procedures has been that medications remain the mainstay of therapy until the disease becomes advanced, despite compliance concerns and adverse effects on the ocular surface. Simply stated, for decades we have had a gaping hole in our therapeutic armamentarium for openangle glaucoma. At one end of the spectrum, we have medications and laser trabeculoplasty, which are modestly effective and very safe. On the other end of the spectrum, we have trabeculectomy and tube shunts, which are highly efficacious but far from safe. The safety gap between medications and lasers on one hand and trabeculectomy and tubes on the other hand has been vast, wide, and persistent. Fortunately, with microinvasive glaucoma surgery (MIGS), that gap is starting to close, good news for the largest proportion of glaucoma patients, those with mild to moderate disease. I performed my first iStent (Glaukos) procedure 8 years ago as an investigator in the first ever Q 2014 ASCRS and ESCRS Published by Elsevier Inc.
U.S. Food and Drug Administration (FDA) premarket approval (PMA) study for a glaucoma device. Yet, it has been less than 2 years since the FDA approved the device for ab interno placement into Schlemm canal for the treatment of mild to moderate glaucoma. Although many remain skeptical that iStent provides enough IOP lowering to meaningfully change the landscape of surgical glaucoma therapy, I believe the stent is the first step in a disruptive reorganization of surgical glaucoma procedures. Admittedly, if the MIGS revolution fails to advance beyond where we are today, it will be a disappointment. More likely, however, MIGS is a game changer that is here to stay. While all concerned would welcome better efficacy with MIGS procedures, few would find fault in the safety data. In stark contrast to the TVT complication rate cited above, adverse events and visual acuity outcomes after phacoemulsification combined with iStent in the U.S. PMA trial were impeccable and not measurably different from those with phacoemulsification alone.4 That an incisional glaucoma operation can be combined with cataract surgery with virtually no measurable increase in adverse events is game changing, period. As glaucoma surgeons, I believe we have become too accepting of complications that “come with the territory.” In fact, vision-threatening complications are simply too common and their occurrence far too unpredictable to subject our patients with mild to moderate glaucoma to the risk of filtration surgery or tube surgery. On the other hand, filtration surgery remains very well suited to patients at high risk for severe vision loss. As surgeons, we must learn to match the risk of the disease process with the risk of the specific surgical modality we offer each patient. The FDA approval for iStent has breathed life into the MIGS movement of alternative glaucoma procedures previously limited to endoscopic cyclophotocoagulation, trabectome, and canaloplasty. The current labeling for iStent is for placement of a single stent at the time of cataract surgery. Belovay et al.5 have reported that multiple stents may result in greater IOP reduction than a single stent. While this is a very promising strategy, I would encourage potential iStent surgeons to get started by placing a single stent, and only when the technique of placing a single stent is mastered consider placing multiple stents. Placing more than 1 stent may be commonplace in the future but remains off label for the time being, and proper disclosure and financial considerations must be addressed. Additional ab interno MIGS 0886-3350/$ - see front matter http://dx.doi.org/10.1016/j.jcrs.2014.06.024
1253
1254
MICROINVASIVE GLAUCOMA SURGERY: GUEST EDITORIAL
technologies are in development including the iStent Inject (second-generation iStent) and the Ivantis Hydrus, an 8.0 mm canal stenting and tensioning device, both in U.S. clinical trials. The obvious advantage of a longer stent is that more collector channels can be accessed, further enhancing outflow. Additionally, tensioning of the meshwork may improve trabecular outflow in regions beyond the inlet that traverses the trabecular meshwork. Finally, supraciliary implants such as the Transcend Cypass or Glaukos iStent Supra offer a subscleral outflow strategy that can be used in conditions such as angle closure or when canalicular procedures fail to adequately lower IOP. Ab interno placement of anterior chamber to subconjunctival devices (AqueSys Xen) are also in trials and show early promise for a more efficient and efficacious glaucoma filtration procedure. While supraciliary and subconjunctival options benefit from lower inherent resistance in their respective outflow reservoirs, they must prove safe given the lack of the episcleral venous backstop that eliminates the risk for hypotony with canal-based procedures. Finally, ab interno trabeculectomy, ie, trabectome, and endoscopic cyclophotocoagulation continue to have an important role in the management of early to moderate glaucoma and many surgeons use these technologies as a safe alternative to transscleral filtration procedures. As IKE Ahmed so beautifully outlined earlier this year,A I strongly believe that the MIGS revolution is disruptive and has forever changed the surgical management of glaucoma. Patients and surgeons alike stand to benefit greatly from the intense research and
development invested in the surgical management of glaucoma over the last decade. It is only the beginning, and the best is yet to come. Thomas W. Samuelson, MD REFERENCES 1. Gedde SJ, Herndon LW, Brandt JD, Budenz DL, Feuer WJ, Schiffman JC; the Tube Versus Trabeculectomy Study Group. Surgical complications in the Tube Versus Trabeculectomy Study during the first year of follow-up. Am J Ophthalmol 2007; 143:23–31 2. Gedde SJ, Schiffman JC, Feuer WJ, Herndon LW, Brandt JD, Budenz DL; on behalf of the Tube Versus Trabeculectomy Study Group. Three-year follow-up of the Tube Versus Trabeculectomy Study. Am J Ophthalmol 2009; 148:670–684 3. Gedde SJ, Herndon LW, Brandt JD, Budenz DL, Feuer WJ, Schiffman JC; on behalf of the Tube Versus Trabeculectomy Study Group. Postoperative complications in the Tube Versus Trabeculectomy (TVT) study during five years of follow-up. Am J Ophthalmol 2012; 153:804–814. Available at: http:// www.ncbi.nlm.nih.gov/pmc/articles/PMC3653167/pdf/nihms380 174.pdf. Accessed June 19, 2014 4. Samuelson TW, Katz LJ, Wells JM, Duh Y-J, Giamporcaro JE; for the US iStent Study Group. Randomized evaluation of the trabecular micro-bypass stent with phacoemulsification in patients with glaucoma and cataract. Ophthalmology 2011; 118:459–467 5. Belovay GW, Naqi A, Chan BJ, Rateb M, Ahmed K II. Using multiple trabecular micro-bypass stents in cataract patients to treat openangle glaucoma. J Cataract Refract Surg 2012; 38:1911–1917
OTHER CITED MATERIAL A. Ahmed IIK, “Microinvasive Glaucoma Surgery: An Idea Whose Time Has Come,” the 2014 Binkhorst lecture presented at the ASCRS Symposium on Cataract, IOL and Refractive Surgery, Boston, Massachusetts, April 2014.
J CATARACT REFRACT SURG - VOL 40, AUGUST 2014
