Phaco and combined phaco-glaucoma surgery lowers IOP, reduces medications

Concomitant phacoemulsification and glaucoma surgery is a viable treatment option for glaucoma patients who have coexisting cataract, with lowered pressure and reduced medications resulting from combined cataract surgery and glaucoma procedures.

“It’s important to realize that there are multiple options that can be combined with cataract surgery to manage glaucoma,” Bradford J. Shingleton, MD, said. “It can be a trabeculectomy, with or without mitomycin, it can be an Ex-PRESS (Alcon) shunt, with or without mitomycin, it can be canaloplasty (iScience Interventional), endoscopic cyclophotocoagulation, tube shunts, Trabectome (NeoMedix), and then there are some internal stents being developed, as well as some suprachoroidal shunts. Our armamentarium is expanding greatly as to what can be done supplemental to cataract surgery at the time of operation.”

Phaco alone or glaucoma surgery followed by a separate phaco procedure are also treatment options, he said. He emphasized that surgical selection for glaucoma patients with coexisting cataract should be based on each patient’s case, including stage of glaucoma and visual significance of cataract.

Combining phaco and glaucoma surgery has been shown to decrease IOP and medication need significantly, most specifically with minimally invasive glaucoma procedures. Also, combining phaco with minimally invasive glaucoma surgery does not typically make to performing the procedures more difficult, clinicians say.

Benefits from concomitant cataract and glaucoma surgery include faster visual rehabilitation, less chance of dangerous IOP spikes, reduced surgical trauma and only one visit to the operating room compared with performing two separate surgeries, according to Arthur J. Sit, SM, MD.

Jeffrey A. Kammer, MD, said that physicians should perform new glaucoma procedures repeatedly, so they are confident in the range of surgical options they offer. Image: Munn R

“It is a single surgery,” Dr. Sit said. “A lot of these patients will eventually need surgery for both glaucoma and cataracts. Glaucoma surgery tends to make cataracts worse, and cataract surgery can cause IOP spikes in glaucoma patients. When somebody needs glaucoma surgery and has a cataract as well, it’s definitely to their advantage in most cases to combine this into a single surgery, to avoid all the risks, time and expense involved in a second surgery.”

However, combining cataract surgery with trabeculectomy does not always result in better overall surgical success and increases risk of complications from the bleb, Jeffrey A. Kammer, MD, said. Filtration blebs in combined procedures are often less diffuse than in trabeculectomy procedures, which is “likely due to the increased surgical trauma and more inflammation that occurs in these combined surgeries,” he said.

Following combined cataract and filtration surgery, bleb manipulation can require fluorouracil supplementation and other interventions. Complications can include hypotony and hyphema.

Dr. Kammer cited a 2002 retrospective, comparative study by Kleinmann and colleagues that compared results of phaco-trabeculectomy and trabeculectomy alone. The study examined 102 eyes of 90 patients in the phaco-trabeculectomy group and 33 eyes of 30 patients in the group that had trabeculectomy with mitomycin C alone. Kleinmann and colleagues found a 31.5% IOP reduction in the combined group, whereas the trabeculectomy-alone group had a 48.5% reduction in pressure with longer follow-up. Medication reduction was similar for both groups.

“There’s some indication that when you’re doing a straight trabeculectomy, the IOP control is better than in combined surgery,” Dr. Kammer said. “You can achieve better pressure control with a straight trabeculectomy based on some articles.”

Combined surgery options

Surgical options for combined procedures include minimally invasive surgeries and filtration surgery, but no one procedure is perfect for all glaucoma patients. Patients can benefit from each procedure’s advantages, Dr. Shingleton said.

“One cannot be dogmatic about indications,” he said. “There’s no absolute right or wrong. We’re in a state of our art and science where we truly can individualize for a given patient the best treatment.”

When selecting a glaucoma surgical option along with cataract surgery, stage of glaucoma is vital. Patients with advanced glaucoma and mild cataract might be best served undergoing trabeculectomy-only or an Ex-PRESS shunt with anti-metabolite enhancement, Dr. Shingleton said. For patients who have conjunctiva scarring, a tube shunt could be an option, he said. Canaloplasty may be considered for patients who are on multiple medications, do not need an extremely low pressure and for whom the complications of a bleb may be particularly problematic.

In mild to moderate glaucoma patients who need reduced medication for many reasons, including intolerance or compliance problems, endoscopic cyclophotocoagulation or Trabectome could be options, Dr. Shingleton said.

Donald S. Minckler

One of the advantages of combining Trabectome with phaco has been that the single incision used for both procedures reduces the risk of astigmatism associated with two-incision combined trabeculectomy. Donald S. Minckler, MD, who has studied the Trabectome procedure extensively, said it is an appealing combined surgical approach because it does not complicate the phaco procedure and is best performed before cataract surgery in combined cases. Research has shown that combining the procedures allows for greater IOP reduction.

“Our general experience is that you get maybe 2 mm Hg or 3 mm Hg with phaco alone, and then maybe 3 mm Hg or 4 mm Hg more by adding Trabectome,” he said. “It’s a procedure you can do quite easily through the same incision. We recommend that you do the Trabectome first so that the angle view is as good as it could possibly be and then enlarge the Trabectome incision and go ahead with your standard phacoemulsification procedure.”

One of the advantages of canaloplasty combined with phaco is its lack of bleb, Dr. Shingleton said. He has studied the procedure combined with phaco and pointed to 3-year data of combined phaco-canaloplasty that has shown that it effectively lowers and controls IOP while also significantly reducing glaucoma medications.

Combined surgery candidates

Dr. Kammer said there are many considerations for performing a combined procedure, including patients’ stage of glaucoma, target IOP, compliance and medication usage. He said selecting the best glaucoma surgical option for combined surgery candidates is often driven by the individual patient’s needs.

“When a patient walks into your office and you’re considering whether to sign them up for straight cataract or combined surgery, there are several factors that you’re looking for,” he said. “I’d say No. 1, whether they have uncontrolled intraocular pressure … you’re looking for patients with uncontrolled glaucoma despite being on maximally tolerated medical therapy, and even laser therapy.”

Other patients who would be good candidates for combined surgery are those with controlled IOP but intolerance to medication or serious compliance issues. Those patients would benefit from the additional reduction in medication provided by combined procedures.

Patients with advanced glaucomatous optic neuropathy and those at risk for postoperative IOP spike would also be good candidates for combined procedures, according to Dr. Kammer, as would patients who cannot have separate surgery because of economic and tolerance issues.

Combined surgery selection

Dr. Kammer said physicians need to perform combined surgery in the manner in which they feel most comfortable, whether as a single- or two-site surgery. They should also learn the newest glaucoma surgical procedures to offer the widest range of surgical options to their patients. Surgeons should perform those procedures repeatedly to enhance their technique.

“You have to familiarize yourself with all the different surgical options at this point, because you need to have experience to be able to offer them to your patients,” Dr. Kammer said. “I think that’s vital, as opposed to just doing it once in a while and then dismissing it as ineffective, when it’s really the fact that you haven’t given it a chance, or perfected your technique. That’s one of the great hurdles that I see in some of the newer glaucoma surgeries. People don’t give the procedure a chance.”

Dr. Minckler said surgical choice can sometimes be based on a surgeon’s specific treatment philosophy and many factors in an individual patient’s case. Minimally invasive surgery procedures can work in cases with higher pressures, depending on desired IOP outcome.

Filtration surgery, while still the gold standard in glaucoma surgery, is not always the best option for treating advanced cases, he said.

“Trabeculectomy is fraught with many difficulties. If you do it with phacoemulsification, at least we always use mitomycin, which is harder to titrate in terms of what effect you get. Sometimes you get these incredibly thin filtering blebs, and there’s a significant risk of infection and leak,” Dr. Minckler said. “Some patients get profound hypotony, which is a horrible problem.”

Phaco alone

In some glaucoma cases, phaco alone could be indicated as treatment, according to Dr. Shingleton. The postoperative pressure reduction from phaco alone is typically minimal, from 1 mm Hg to 2 mm Hg. That reduction can last up to 5 years, according to published data.

Research has shown that pretreatment pressure is indicative of final pressure reduction, he said. For instance, in patients with healthy nerves and minimal glaucoma medication requirements but with IOP upwards of 25 mm Hg to 30 mm Hg, phaco alone could result in an 8 mm Hg to 12 mm Hg reduction.

“If the pressure’s elevated, but the nerve is very healthy, then the phacoemulsification is a good procedure just by itself and especially if they have somewhat narrow angles,” he said.

For patients with mild to moderate glaucoma, narrow angles and pseudoexfoliation, cataract surgery alone can be highly effective in reducing IOP and medication use, Dr. Shingleton said. The need for medications tends to increase to pretreatment level in 3 to 5 years.

“Cataract surgery alone provides the most rapid visual recovery compared to all the procedures. You can still do a glaucoma operation later. This certainly has a role in the decision-making process for patients with cataract and glaucoma,” he said.

Malik Y. Kahook, MD, said physicians should be aware of current research into why phacoemulsification has a pressure-reductive effect. Current explanations for reduction of IOP after phacoemulsification include the potential of lens removal resulting in the opening of narrow angles as well as the potential for phaco ultrasound to affect the structure of trabecular meshwork and surrounding extracellular matrix.

A 2009 study by Poley and colleagues examined long-term results of phaco with IOL implantation on glaucomatous and nonglaucomatous eyes. They found that IOP reduction in the early postop period was sustained for 10 years, suggesting that a major cause of ocular hypertension and glaucoma may be the aging crystalline lens.

A 2003 study by Wang and colleagues examined the connection between phacoemulsification alone and IOP reduction. That study found that the ultrasonic energy experienced during phaco may result in the secretion of proteins that could modulate the tissue of the drainage system. Phaco ultrasound appeared to cause an IOP-lowering stress response in the trabecular meshwork cells.

“The mechanism for lowering pressure after phacoemulsification is probably multifactorial,” Dr. Kahook said. “We know that removal of the lens in some cases leads to a change in the anatomy of the angle, which can increase drainage of fluid, by virtue of opening up the drainage system. That, on its own, is not likely to be the only cause of decrease in pressure. We often see patients who have wide-open angles on gonioscopy who then subsequently have significant IOP lowering post-phacoemulsification. In my experience, this effect has lasted up to 3 years. This phenomenon may be due to the direct effect of ultrasonic energy on the outflow system of the eye.”

Arthur J. Sit

Dr. Sit said more research is needed to determine the mechanisms of action for IOP reduction with cataract surgery as well as minimally invasive glaucoma surgical techniques.

“I think it’s unclear exactly why cataract surgery improves IOP. It’s pretty clear that it does somehow. Whatever the mechanism is, it’s certainly possible that some of the mechanisms might be synergistic with newer glaucoma surgeries, such as Trabectome, that focus on the angle,” he said.

One consideration with cataract surgery alone is the potential for high IOP spikes following surgery. Between 10% and 37% of patients undergoing cataract surgery had spikes high enough that they needed postoperative medical intervention, Dr. Kammer said. Such spikes can be detrimental to the visual fields of patients with advanced glaucoma.

However, combining both cataract and glaucoma procedures can decrease that risk by lowering IOP during surgery. Dr. Kammer said that performing straight cataract surgery on glaucoma patients under tenuous control can be a double-edged sword. While it may lower the IOP, it could also cause a severe IOP spike that is recalcitrant to medical therapy. He recommended that surgeons be prepared to perform urgent glaucoma surgery if a dangerous IOP spike occurs postoperatively.

Separate procedures

In addition to combined procedures or phacoemulsification alone, another option for glaucoma patients with coexisting cataract is performing glaucoma surgery first, followed at a later date by phaco. Dr. Shingleton said the option seems best indicated in some advanced glaucoma cases or active neovascular glaucoma and active inflammatory glaucoma cases.

Performing the surgeries separately would allow for a more active approach to refractive outcomes following trabeculectomy cases. Such cases would benefit from additional time to correct astigmatism induced by surgery.

“Once you are confident that the IOP is stabilized, you could implant a toric IOL or perform limbal relaxing incisions to give patients the refractive outcomes that they desire,” Dr. Kammer said.

One drawback of performing glaucoma and cataract surgery at different times would be that it requires two separate visits to the OR, which could increase the risk of complications. Another drawback, especially in advanced cases undergoing trabeculectomy, would be the delay in visual recovery when compared with combined procedures.

“There are trade-offs to each option you may choose. The trade-off is, you have to wait for the trabeculectomy to fully recover and then do it. So while you may ultimately get a little better vision because you can address the astigmatism issue, they’re going to be waiting for a few months. And if you’re dealing with a type-A individual, they may not be too happy about that,” Dr. Kammer said. – by Erin L. Boyle

Would you consider early phacoemulsification to manage IOP in a patient with modestly uncontrolled glaucoma?

References:

• Francis BA, Minckler D, Dustin L, et al; Trabectome Study Group. Combined cataract extraction and trabeculotomy by the internal approach for coexisting cataract and open-angle glaucoma: initial results. J Cataract Refract Surg. 2008;34(7):1096-1103.
• Kleinmann G, Katz H, Pollack A, Schechtman E, Rachmiel R, Zalish M. Comparison of trabeculectomy with mitomycin C with or without phacoemulsification and lens implantation. Ophthalmic Surg Lasers. 2002;33(2):102-108.
• Poley BJ, Lindstrom RL, Samuelson TW, Schulze R Jr. Intraocular pressure reduction after phacoemulsification with intraocular lens implantation in glaucomatous and nonglaucomatous eyes: evaluation of a causal relationship between the natural lens and open-angle glaucoma. J Cataract Refract Surg. 2009;35(11):1946-1955.
• Shingleton B, Tetz M, Korber N. Circumferential viscodilation and tensioning of Schlemm canal (canaloplasty) with temporal clear corneal phacoemulsification cataract surgery for open-angle glaucoma and visually significant cataract: one-year results. J Cataract Refract Surg. 2008;34(3):433-440.
• Wang N, Chintala SK, Fini ME, Schuman JS. Ultrasound activates the TM ELAM-1/IL-1/NF-kappaB response: A potential mechanism for intraocular pressure reduction after phacoemulsification. Invest Ophthalmol Vis Sci. 2003;44(5):1977-1981.

• Malik Y. Kahook, MD, can be reached at Rocky Mountain Lions Eye Institute, University of Colorado Denver School of Medicine, 1675 Aurora Court, P.O. Box 6510, Mail Stop F731, Aurora, CO 80045; 720-848-2500; fax: 720-848-5014; e-mail: malik.kahook@ucdenver.edu. Dr. Kahook consults for and has received research support from Alcon.
• Jeffrey A. Kammer, MD, can be reached at Vanderbilt Eye Institute, 2311 Pierce Avenue, Nashville, TN 37232-8808; 615-936-7190; fax: 615-936-1540; e-mail: jeffrey.kammer@vanderbilt.edu.
• Donald S. Minckler, MD, can be reached at e-mail: minckler@uci.edu.
• Bradford J. Shingleton, MD, can be reached at Ophthalmic Consultants of Boston Inc., 50 Staniford St., Suite 600, Boston, MA 02114; 617-367-4800; fax: 617-589-0552; e-mail: bjshingleton@eyeboston.com.
• Arthur J. Sit, SM, MD, can be reached at Department of Ophthalmology, College of Medicine, Mayo Clinic, 200 First Street SW, Rochester, MN 55905; 507-266-4918; fax: 507-284-4612; e-mail: sit.arthur@mayo.edu. Dr. Sit has received research support from NeoMedix.