The in-tandem surgical dilemma

When surgeons see evidence of glaucoma and cataracts in a patient, challenges multiply.

By Karen Blum, Contributing Editor

Nearly 20% of cataract patients have some degree of comorbid glaucoma.¹ So, should ophthalmic surgeons perform cataract surgery alone or in conjunction with glaucoma procedures in patients with both conditions?

“It’s a constant dilemma,” says David Friedman, MD, MPH, PhD, director of the Dana Center for Preventive Ophthalmology at Johns Hopkins’ Wilmer Eye Institute in Baltimore. “Typically, glaucoma affects those who are older and many of them have cataracts, so you’re often dealing with [questions of] what’s in the best interest, long term, for the patient.”

There’s an “intimate relationship” between cataracts and glaucoma, adds Davinder S. Grover, MD, MPH, an attending surgeon and clinician at the Glaucoma Associates of Texas in Dallas. “My favorite way of thinking is the best glaucoma surgeon is also a good cataract surgeon, because there is such a close relationship between the two.”

The glaucoma-cataract connection

Performing cataract surgery in patients who also have glaucoma poses unique challenges, Dr. Grover says.² One is anatomy. For example, patients who have pseudoexfoliation glaucoma usually have a small pupil and sometimes weak zonules. In geneeral, eyes affected by glaucoma tend to be sicker and have smaller pupils, he says. In addition, patients with angle-closure or narrow-angle glaucoma also tend to have smaller eyes, leaving less room for a surgeon to operate. There’s also a much higher risk for aqueous misdirection during or after surgery, Dr. Grover says.

Then there’s the chicken-or-egg dilemma. Cataract surgeries in glaucoma patients can lead to a postoperative spike in intraocular pressure, and these patients could be more susceptible to damage from this transient increase, resulting in a worsening of their glaucoma. On the other hand, glaucoma surgeries like trabeculectomy or tube shunt can cause a cataract to worsen.³ “But combining cataract surgery with these full-thickness procedures almost certainly lowers the long-term success rate for eye pressure control,” Dr. Friedman says.

Pro-combo

Surgeons have various options available to treat both conditions. While some of the newer procedures, like endoscopic cyclophotocoagulation (ECP) or trabecular micro-bypass stent (iStent), may be less effective than trabeculectomy, they also have a lower risk of surgical complications.⁴ Factors in choosing an option include how well a patient’s glaucoma is controlled and how many medications the patient takes, say those interviewed. Also, the primary reason for the patient’s visit should be considered — is it because of the cataract or because of the glaucoma?

Cataract surgery alone can modestly decrease intraocular pressure in patients with standard primary open-angle glaucoma, while those with pseudoexfoliation glaucoma or primary angle-closure glaucoma may see more significant IOP reductions of 20% to 30%.1 Cataract surgery can be combined with minimally invasive to more invasive procedures. “You really have to tailor your choice [of surgery] to the individual patient,” says Sarah Wellik, MD, an associate professor of clinical ophthalmology with the University of Miami Bascom Palmer Eye Institute.

For most patients with mild to moderate open-angle glaucoma who do fine on one drop, “I think you can be comfortable offering them either just cataract surgery or cataract surgery with one of the newer procedures available,” such as noninvasive or minimally invasive glaucoma surgeries (MIGS), Dr. Wellik says. She mainly uses the iStent in these patients, while some colleagues use ECP. “I think the outcomes of those procedures are not so different, and it really depends on surgeon preference and [the surgeon’s] comfort level with the various procedures.” Patients with more severe or uncontrolled glaucoma could be better served by a combined cataract surgery with trabeculectomy or tube shunt, she says. A study she coauthored demonstrated that patients undergoing trabeculectomy or tube surgery plus cataract surgery tended to have more astigmatism, but nearly 75% still met the target refraction of -1.00D to +0.50D.⁵

Christine Larsen, MD, a surgeon with Minnesota Eye Consultants, says she tends to favor combined procedures for many patients because IOP can be unpredictable after cataract surgery alone, at least in open-angle glaucoma patients. Cataract surgery combined with filtering surgery is for more severe or uncontrolled disease, she says, and cataract surgery alone or cataract surgery plus MIGS is reserved for patients who have stable, well-controlled mild to moderate glaucoma.

“I always approach the surgery as if there is no guarantee that cataract surgery alone will lower the pressure and that I may even see pressure rise after surgery, so I try to anticipate that,” Dr. Larsen says. If patients have allergies to other classes of medications, she also favors combined procedures “because there’s not a lot in reserve should I encounter a pressure spike after surgery. Their treatment options are limited at that point.”

Dr. Grover agrees and favors isolated glaucoma surgery for glaucoma patients who only have a mild, bothersome cataract. Similarly, if a patient has glaucoma with narrow angles that are thought to be primarily caused by the cataract, he’ll perform cataract surgery alone. If the patient needs both glaucoma and cataract operations, or if there’s a question of how best to serve the patient, he tends to favor combined surgeries as well, such as phacoemulsification plus a MIGS procedure, gonioscopy-assisted transluminal trabeculectomy, a trabectome, ECP or other combination.⁶

“It’s all a matter of effective delivery of care and also better outcomes,” he says. “My goal is to take a patient to the operating room once and get everything done. I tell my patients, ‘This is a unique opportunity to kill two birds with one stone, to improve your vision and to decrease your dependence on medications.’”

Studies have shown that combined surgeries may lead to better outcomes, he says. One recent meta analysis found some evidence that combined procedures (cataract surgery plus either trabeculectomy, iStents or trabecular aspiration) led to better IOP control a year after surgery compared to cataract surgery alone.⁷

Dr. Grover describes his personal algorithm this way: If a patient has mild glaucoma, is on one glaucoma drop and is well controlled, he’ll consider either an isolated cataract surgery or a combined procedure like phacoemulsification plus an iStent, depending on the patient. If patients are on a few drops and have moderate to advanced glaucoma, he uses phacoemulsification plus GATT. If patients have very advanced glaucoma and uncontrolled IOP, he’ll consider phacoemulsification plus trabeculectomy, or phacoemulsification plus tube shunt. If patients are taking a few medications, are well controlled but have extremely advanced glaucoma, they too can benefit from more invasive glaucoma procedures with cataract removal.

The introduction of MIGS has helped present more choices, Dr. Grover says: “A lot of MIGS procedures don’t add a lot to the risk of the surgery but add a lot to the potential benefit. That’s what I tell my patients all the time.”

Keeping them separate

Dr. Friedman confesses to having a more conservative surgical approach. “The decision-making always revolves around the level of control of the glaucoma, and what’s foremost in your mind.” About 20% of glaucoma surgery patients will need cataract surgery within five years. But, unless the cataract bothers the patient, he says he wouldn’t necessarily take it out just because he’s already in the OR doing a glaucoma procedure. Also, if the patient is moderately well controlled, “Glaucoma surgeries don’t last forever ... You could argue that, if I am doing an operation that may not be necessary … and it doesn’t last forever, maybe I can hold off for now.”

Dr. Friedman offers a cautionary note. “If you told me it was like drinking water to have this additional pressure lowering, I would tell everybody to drink the water.” But, he continues, “ECP doesn’t sound like drinking water to me — you’re destroying part of the ciliary body.” As for the MIGS, some of the procedures “involve putting a foreign body in the eye and [they don’t] seem to offer a huge amount of pressure lowering in published clinical trials.”

There are other cases in which combined surgery should be avoided, say those interviewed, such as in patients with uveitis, patients taking blood thinners, the very elderly or those who are very ill.

“If somebody has clearly limited life expectancy or some terminal illness, one has to keep the glaucoma in perspective,” Dr. Friedman says. “It’s a slowly progressive illness for most patients, and so I think it’s OK to just go ahead and do the cataract surgery in many of these patients.”

If patients are high-risk incisional surgical candidates, Dr. Larsen says she discusses a less invasive glaucoma procedure like transscleral laser cyclophotocoagulation. Traditionally, she says, diode laser has been reserved for more advanced cases and patients with poor visual potential. Micropulse therapy may have a potential role for patients with better visual reserve.

If a patient presents with significant inflammation or with abnormally high pressure, Dr. Grover says he will do a glaucoma procedure first, such as a tube shunt or Ahmed valve, “to get them out of trouble,” then treat the inflammation, and schedule a cataract surgery six months out. It’s common for neovascular glaucoma patients, for example, to come in with a cloudy cornea and high pressure, he says.

With no perfect, one-size-fits-all solution, the surgeons say they will continue to look to the literature for guidance (See New research ). OM

Dr. Friedman has been a consultant for Alcon and Allergan. Dr. Grover is a speaker for Allergan and Reichert Technologies. Drs. Wellik and Larsen reported no relevant financial disclosures.

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