Glaucoma surgery a viable early treatment option in certain cases

While topical medications are still the first-line treatment for most glaucoma patients, medical therapy has many side effects and compliance issues, placing newer surgical options ever more readily at the forefront of treatment options.

“As clinicians, our responsibility to our patients includes maximal likely benefit with minimal possible harm,” Ivan Goldberg, AM, MBBS, FRANZCO, FRACS, OSN Asia-Pacific Edition Editorial Board Member, said. “As much as possible, the patient needs to be an informed participant in choosing between treatment options. Because current glaucoma surgery is unpredictable, with possible short-term and long-term complications, we tend to consider surgical options only when less potentially risky medical and/or laser strategies have been considered.”

There are a variety of glaucoma surgical options, from nonpenetrating to less invasive penetrating procedures. Trabeculectomy remains the most commonly performed glaucoma operation, but it is generally performed only in advanced glaucoma cases in which medical treatment and lasers have failed. Minimally invasive procedures can be offered earlier in the course of the disease because of their greater safety.

Opinions vary among glaucoma specialists on the role and efficacy of minimally invasive procedures as an early surgical approach in glaucoma. Many glaucoma specialists agree that trabeculectomy and tube shunts are still preferred for advanced glaucoma and that they will continue to play a major role until the efficacy of other minimally invasive surgical procedures is firmly demonstrated.

Elie Dahan, MD, MMed (ophth), said the paradigm of medical treatment preceding surgery should be “thoroughly reviewed.” Image: Dahan E

Glaucoma surgery is typically indicated when maximum-tolerated medical therapy and appropriate laser treatment are inadequate for controlling IOP.

However, glaucoma surgery could be a viable option as first-line treatment in certain cases, according to Elie Dahan, MD, MMed (Ophth), OSN Europe Edition Editorial Board Member.

“The paradigm of first medical treatment and then surgery has to be thoroughly reviewed,” Dr. Dahan said. “This is particularly true for patients who have long life expectancy and present for the first time with high IOPs and obvious advanced glaucomatous damage. Long-term topical medical anti-glaucoma treatment has adverse effects on the outcomes of glaucoma surgery, so when it is obvious that a particular patient will eventually need glaucoma surgery, it is logical to operate rather early on a virgin conjunctiva than late on an irritated and altered conjunctiva. Operating on a virgin conjunctiva increases the chances of achieving complete success — good IOP control without additional medical therapy.”

Minimally invasive surgical procedures include ab interno trabeculectomy with Trabectome (NeoMedix), canaloplasty (iScience Interventional), endoscopic cyclophotocoagulation (ECP), and phacoemulsification with or without other minimally invasive procedures. The iStent (Glaukos), a trabecular micro-bypass system inserted ab interno and implanted into Schlemm’s canal, has introduced another option for patients.

Thomas W. Samuelson

In a presentation at OSN New York 2010, Thomas W. Samuelson, MD, OSN U.S. Edition Glaucoma Section Editor, said that minimally invasive procedures enhance the natural outflow system of the trabecular meshwork, rather than creating a new drainage system, and are not associated with the severe complications that may result from penetrating surgery.

“Unfortunately, transscleral procedures carry more risk than some of the newer, more minimally invasive procedures and therefore, while still very relevant, they should be reserved for patients with more serious levels of glaucoma,” Dr. Samuelson said in a subsequent telephone interview.

First-line potential

Some surgeons think that the new procedures should be used only in patients with early disease. Others suggest that prospective, randomized clinical trials be conducted to compare minimally invasive procedures with transscleral procedures and further determine their efficacy. Still others think that the minimally invasive procedures are appropriate for the treatment of moderate disease and that their safety may even warrant usage in cases of advanced glaucoma as a first-line treatment.

Dr. Dahan said surgery as first-line treatment could be the best option for younger patients with open-angle glaucoma, pigmentary glaucoma or pseudoexfoliation glaucoma; adult patients with narrow-angle glaucoma, when phacoemulsification is concurrently performed to widen the angle; and in patients with congenital or juvenile glaucoma, because of their long life expectancy.

Dr. Dahan mainly performs two types of glaucoma surgery: deep sclerectomy with the T-Flux nonabsorbable hydrophilic implant (Carl Zeiss Meditec) and the Ex-PRESS mini glaucoma shunt (Alcon) implanted under a scleral flap. In intractable cases in which all other methods have failed, he performs an augmented trabeculectomy that includes a modified deep sclerectomy and iridencleisis under a scleral flap.

“Surgery as first-line treatment has better chances to achieve complete success, IOP control by surgery only, because it is performed on a virgin conjunctiva,” Dr. Dahan said. “Furthermore, the need for mitomycin C and other wound-healing agents might be reduced in patients who are offered surgery as first-line treatment.”

Dr. Goldberg performs trabeculectomy with or without a shunt and uses glaucoma drainage devices and cyclodiode laser. He said the use of these surgeries as first-line treatment remains rare. Still, these options offer potential for sustained IOP reduction early in treatment or as first-line treatment in relatively unusual situations, but intensive care is needed in the immediate postoperative stage, he said.

“These [cases] might include young patients with high IOP and advanced damage on diagnosis, particularly if that damage is threatening fixation, or patients who cannot access medical or laser treatment in a sustained manner for social, economic or geographic reasons,” Dr. Goldberg said. "In this latter group, this indication must be balanced against the probable lack of sustained follow-up care for a patient with what we hope will be a functioning bleb. In itself, this poses a challenge.”

Dr. Dahan outlined the story of a patient operated more than 20 years ago that illustrates the fate of advanced untreated glaucoma cases often encountered in the poor health care environment of Africa. The male South African patient, a 65-year-old retired teacher, presented for the first time with advanced open-angle glaucoma in both eyes, with IOP of 28 mm Hg in his right eye and 35 mm Hg in his left eye. He also had bilateral incipient cataracts. He was offered surgery for both eyes but decided to undergo surgery (combined cataract removal and trabeculectomy) only in his left, worse eye.

“Two years later, he returned to the St. John Eye Hospital in Johannesburg asking for reading glasses. In the meantime, his ‘good,’ unoperated right eye lost light perception due to end-stage glaucoma, whereas his left, ‘bad’ eye that was operated on presentation retained vision of 20/40, with a tubular visual field and 11 mm Hg IOP on no medications,” Dr. Dahan said. “Since that story, I have witnessed many more cases where the ‘bad’ eye became the only seeing eye because it was operated on presentation, whereas the ‘good,’ seeing eye was lost due to the progression of the glaucoma.”

Dr. Dahan also said that modern glaucoma surgery may be offered as first-line treatment for patients who have more than 10 years of life expectancy because of the unavoidable compliance issues with medical treatment and the better chances for achieving complete success in virgin eyes.

He outlined the various side effects associated with long-term topical medical therapy that alter the conjunctiva cells’ profile by reducing the goblet cell population, causing dry eye and eventually leading to poor compliance.

“The adverse effects of long-term topical medical therapy on the outcomes of glaucoma surgery are well-known and have been reported on extensively in the literature,” he said.

Nonpenetrating surgery

Even though the role and effectiveness of minimally invasive surgeries remain debatable, most surgeons agree that these procedures are safer than transscleral surgeries. They also have potential as first-line options.

“The minimally invasive glaucoma surgeries offer lower risk but at the cost of less intraocular pressure-lowering efficacy,” Joel S. Schuman, MD, FACS, OSN U.S. Edition Glaucoma Board Member, said.

Joel S. Schuman

According to Dr. Schuman, ab interno trabeculectomy is one of the least invasive, but also least effective, procedures. Because of the mediocre success rate of this procedure when used by itself, Dr. Schuman nearly always performs ab interno trabeculectomy only in combination with phacoemulsification. The combined procedure often lowers IOP to the mid-to-high teens and may relieve patients of the need to use medication.

Hyphema is a common complication after ab interno trabeculectomy but can be avoided with high-quality wound construction, Dr. Schuman said. He cautioned that surgeons should avoid extending the Trabectome device too far posteriorly to avoid cyclodialysis.

Canaloplasty, a more invasive procedure, is performed much like nonpenetrating surgery, such as viscocanalostomy or deep sclerectomy, and is prescribed to patients who require target IOP in the mid-to-high teens, Dr. Schuman said. He usually combines phacoemulsification with a procedure that is less invasive than canaloplasty. He does not perform phacoemulsification alone as a glaucoma treatment if he needs to lower IOP by more than 1 mm Hg or 2 mm Hg.

Canaloplasty shares the risks of other nonpenetrating surgeries.

Dr. Schuman said he avoids performing ECP alone because it does not dramatically lower IOP and can cause significant postoperative inflammation. He said he also hesitates to combine this procedure with phacoemulsification because recovery time is longer than for phaco alone. In addition to destroying the ciliary body and causing inflammation, ECP increases the risk of macular edema, Dr. Schuman said.

Penetrating surgery

Douglas J. Rhee, MD, OSN U.S. Edition Glaucoma Board Member, said that the primary indication for trabeculectomy is a target pressure of less than 14 mm Hg.

Dr. Rhee does not perform trabeculectomy if the conjunctiva has previously been operated on, such as with trabeculectomy, vitrectomy or canaloplasty. Moreover, the advent of minimally invasive procedures has prompted him to limit his surgical indications because of the risks associated with trabeculectomy.

Intraoperative and perioperative risks include infection, retinal detachment, expulsive hemorrhage and suprachoroidal hemorrhage, all of which may have devastating effects on visual acuity, Dr. Rhee said. He also discussed bleb leak, blebitis and infection as potential long-term risks.

“It would not be rare to have a patient do beautifully for 5 years … and then all of a sudden, a severe bleb-related infection could threaten eyesight. That could happen anytime in the lifetime of that bleb, 5 years later, 10 years later,” Dr. Samuelson said. “There are very few surgeries that subject patients to unending, serious risk.”

However, despite potential complications, some surgeons think transscleral procedures such as trabeculectomy are more reliable than the newer surgeries because extensive testing and clinical experience have made them more predictable.

According to Dr. Rhee, in the realm of clinical practice, there are generally two schools of thought regarding trabeculectomy. Some prefer to tie the sutures tighter and gradually reduce pressure by either using a laser to cut one of the internal sutures or using releasable sutures; this preference stems from a strong desire to avoid hypotony.

Other surgeons, Dr. Rhee said, seek to achieve low IOP immediately and use either atropine or a small amount of viscoelastic in the anterior chamber or allow for postoperative leaks.

In the case of tighter sutures, surgeons can avoid flat anterior chambers but must invest significant time into postoperative care, George L. Spaeth, MD, OSN U.S. Edition Glaucoma Board Member, said. This requirement limits the approach to patients who are able and willing to attend follow-up exams.

Another option for patients who undergo transscleral surgery is trabeculectomy with the Ex-PRESS. In his presentation, Dr. Samuelson said that the device does not enhance the efficacy of a standard trabeculectomy but does enable more surgical control and improves safety.

“You make a tiny little incision, and the anterior chamber doesn’t shallow, and the iris doesn’t prolapse, and you do not get bleeding from the ciliary body. … There is more wound control. There is less induced astigmatism,” Dr. Samuelson said, adding that there is less choroidal effusion and postoperative hypotony.

“You still need very good trabeculectomy techniques, but it’s safer, it’s more elegant, it’s reproducible, and it’s less invasive,” he said.

In the follow-up interview, Dr. Samuelson again distinguished between standard trabeculectomy and trabeculectomy with the Ex-PRESS shunt by stating that the first surgery requires surgeons to excise tissue and the second surgery does not, meaning that the device eliminates the possibility of excising too far posterior and causing bleeding from vascular tissue.

Tube shunts

The indications for inserting tube shunts vary, depending on the surgeon. Most agree that a failed conjunctival filtration surgery or high risk for bleb infection are consistent indications.

Conjunctival scarring from ocular operations, such as retinal detachment surgery or ruptured globe surgery, generally suggests the need for tube surgery, Dr. Rhee said.

“Tubes are much less labor intensive from the point of view of patient care, especially postoperatively,” Dr. Spaeth said, comparing the procedure to trabeculectomy. “There are certain parts of the world where that is an important consideration.”

Some surgeons encounter complex patient histories that may lend themselves to implantation of tube shunts.

“A tremendous number of patients in my practice have had grafts and stem cell transplants and just very complicated situations, and tubes have been a lifesaver in those patients,” Dr. Samuelson said at OSN New York.

The primary risk associated with this procedure is diplopia, Dr. Samuelson said, but Dr. Spaeth said that the number of patients who suffer from this complication is less than 5%.

“I would say having the reservoir well centered between the muscles is important to try to reduce or eliminate the risk for diplopia,” Dr. Samuelson said.

Future

Most glaucoma specialists agree that penetrating procedures will play a role in the future in the treatment of diseases such as uveitic glaucoma, neovascular glaucoma and advanced glaucoma that has either been diagnosed late or has failed to respond to less invasive procedures.

Dr. Spaeth does not think newer procedures will be efficacious as treatment for more advanced disease.

“There is fairly good pathologic evidence demonstrating that, with people who have had glaucoma for a long time, the resistance to outflow is no longer in the trabecular meshwork but in the collector channels. Clearly, if what you are trying to do is shunt aqueous from the anterior chamber to the collector channels, and the collector channels are not working, that operation is not going to work,” Dr. Spaeth said.

Nevertheless, Dr. Spaeth shares the popular opinion that these procedures are appropriate for patients with early disease or those who are highly susceptible to infection from a bleb. In the future, advancements could enhance available options, Dr. Goldberg said.

“When surgical approaches are refined and become more predictable, I believe they will be able to be recommended to more patients earlier in the course of their glaucoma management,” Dr. Goldberg said. — by Michelle Pagnani and Erin L. Boyle

Do you prefer implants or trabeculectomy when treating patients with advanced glaucoma?

References:

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• Budenz DL, Barton K, Feuer WJ, et al. Treatment outcomes in the Ahmed Baerveldt Comparison Study after 1 year of follow-up. Ophthalmology. 2011;118(3):443-452.
• Dahan E, Carmichael TR. Implantation of a miniature glaucoma device under a scleral flap. J Glaucoma. 2005;14(2):98-102.
• Dahan E, Drusedau MU. Nonpenetrating filtration surgery for glaucoma: Control by surgery only. J Cataract Refract Surg. 2000;26(5):695-701.
• De Jong L, Lafuma A, Aguadé AS, Berdeaux G. Five-year extension of a clinical trial comparing the EX-PRESS glaucoma filtration device and trabeculectomy in primary open-angle glaucoma. Clin Ophthalmol. 2011;5:527-533.
• Gedde SJ, Heuer DK, Parrish RK 2nd. Tube Versus Trabeculectomy Study Group. Review of results from Tube Versus Trabeculectomy Study. Curr Opin Ophthalmol. 2010;21(2):123-128.

• Elie Dahan, MD, MMed (Ophth), can be reached at Ein Tal Eye Center, 17 Brandeis St., Tel Aviv 62001, Israel; +97235433222; fax: +97235441222; email: elie.dahan@gmail.com.
• Ivan Goldberg, AM, MBBS, FRANZCO, FRACS, can be reached at 187 Macquarie St. Park House, Floor 4, Suite 2, Sydney, NSW 2000, Australia; +61-2-9247-9972; fax: +61-2-9232-3086; email: eyegoldberg@gmail.com.
• Douglas J. Rhee, MD, can be reached at Massachusetts Eye and Ear Infirmary, 243 Charles St., Boston, MA 02144, U.S.A.; +1-617-573-3670; email: dougrhee@aol.com.
• Thomas W. Samuelson, MD, can be reached at Minnesota Eye Consultants, 701 E. 24th St., Suite 100, Minneapolis, MN 55404, U.S.A.; +1-612-813-3628; fax: +1-612-813-3656; email: twsamuelson@mneye.com.
• Joel S. Schuman, MD, FACS, can be reached at UPMC Eye Center, University of Pittsburgh School of Medicine Dept. of Ophthalmology, Eye and Ear Institute, 203 Lothrop St., Suite 816, Pittsburgh, PA 15213, U.S.A.; +1-412-647-2205; email: schumanjs@upmc.edu.
• George L. Spaeth, MD, can be reached at Wills Eye Institute, 840 Walnut St., Philadelphia, PA 19107, U.S.A.; +1-215-928-3197; email: gspaeth@willseye.org.
• Disclosures: Dr. Dahan is a consultant for Alcon. Dr. Goldberg is a member of advisory boards for Alcon, Allergan, Merck and Pfizer. Dr. Rhee is a consultant and has research support from Alcon. Dr. Samuelson is a consultant for AMO, Alcon Surgical, Glaukos, AqueSys, Ivantis and Endo Optiks. Dr. Schuman receives royalties for intellectual property licensed by MIT to Carl Zeiss Meditec. Dr. Spaeth has no direct financial interest in any of the products discussed in this article, nor is he a paid consultant for any companies mentioned.