May 2014

 

COVER FEATURE

 

Glaucoma

Making the case for cataract surgery in angle closure glaucoma patients


by Vanessa Caceres EyeWorld Contributing Writer

 
   

An eye with a cataract and elevated IOP Source: Pekka Virtanen

Procedure is simpler than glaucoma surgery, helps to lower IOP

Cataract surgery for angle closure glaucoma (ACG) patients is coming into its heyday. A mere 8 years ago, authors of a Cochrane review paper made the following conclusion: "There is no evidence from good quality randomized trials or non-randomized studies of the effectiveness of lens extraction for chronic primary angle-closure glaucoma."1

Fast forward to 2014, and a paper in Current Opinion in Ophthalmology in March stated that data suggest that cataract extraction in those with angle closure may be more effective for controlling IOP than laser or incisional glaucoma procedures.2

Of course, the increasing use of cataract surgery to treat ACG doesn't come from just one published paper. Clinicians base that decision on a variety of research and clinical experience.

"This is a changing area of clinical care," said David S. Friedman, MD, PhD, Alfred Sommer professor, Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimoreand co-author of the 2006 review paper mentioned above. "There will be more and more evidence about how to treat angle closure glaucoma, and several clinical trials are nearing completion." Dr. Friedman pointed to the large EAGLE trial underway in England and Asia to evaluate the cost effectiveness and clinical outcomes of early lens extraction in ACG. Results are expected in the next year or two.

When to use cataract surgery

Glaucoma surgeons consider a few factors when deciding to perform cataract extraction in patients with ACG. One consideration is how much the procedure will lower IOP.

"If patients have a hyperopic eye with a crowded angle, then removing the lens will typically lower the pressure at least a few millimeters," said Nicholas P. Bell, MD, director of the glaucoma service, Robert Cizik Eye Clinic, and A.G. McNeese Jr. clinical associate professor, Ruiz Department of Ophthalmology & Visual Science, UTHealth, Houston. "The reason to remove the lens is to treat primary angle closure by deepening the angle. The decrease in IOP is a result of successful alteration of the anterior chamber anatomy. Patients with narrower angles may get even greater pressure lowering than we typically expect from cataract surgery."

Another consideration is whether cataract surgery can help patients avoid more complex glaucoma surgery. For instance, Reay H. Brown, MD, founding partner, Atlanta Ophthalmology Associates, said he performed cataract surgery in 83 eyes with ACG, and the average pressure reduction was 5.3 mmHg in patients with a preop IOP of 20 or higher. The pressure was reduced in 100% of eyes with preop IOP of 18 or above. "It's not something you can bet the ranch on, but when you can do the cataract surgery by itself, I think you should. You have the chance to help the patient and do it without the risk of glaucoma surgery," he said. A grayer area is when to perform clear lens extraction in these patients. "Clear lens extraction has its own negatives, and there's a small risk of retinal detachment and macular edema. When you make people pseudophakic, you can use multifocal lenses, but that leaves many people with presbyopia and they don't like it. If a patient has a dangerously high pressure, I think it's reasonable to take out the lens," Dr. Friedman said.

"You have to talk to the patients about it," Dr. Bell said. "As an alternative to laser iridotomy for the initial treatment of primary angle closure, I offer it to higher hyperopes who have functional visual complaints related to cataract even if their visual acuity may not be worse than 20/40."

"These aren't patients who are saying they can't see the golf ball or a road sign," said Dr. Brown. "The trigger for doing something is that they have angle closure and their pressures are too high despite maximal medical therapy. You can do a trabeculectomy, a tube shunt, or cataract [surgery]. If you can solve the problem with a cataract surgery, you've done the patient an incredible service."

It's important to make sure the patient has an apparent medical need for clear lens extraction, said Dr. Brown. For example, a patient with no elevated pressure using only one glaucoma drop would not be an ideal clear lens extraction candidate; a patient on 3 to 4 medications with continuing pressure elevation is a stronger candidate.

How about goniosynechialysis?

When should a goniosynechialysis be done along with cataract surgery? Dr. Friedman believes if the synechiae are there a long time, it is not clear whether or not just removing them will be of benefit. "If they are relatively acute, there may be a good argument for breaking those with surgery. A month or two out, you might have synechiae that have already damaged the trabecular meshwork," he added.

It is difficult to show the exact benefit of goniosynechialysis as there likely will never be a trial to compare patients who have had that procedure against those who have not, Dr. Brown said. Instead, glaucoma surgeons must rely on inconsistent evidence from the literature and their clinical experience. "I'll do goniosynechialysis if there's no more than 180 degrees, and if I get any bleeding, I stop," he said. In his hands, Dr. Bell finds that the procedure can help if it is done within the first 6 to 12 months after peripheral anterior synechiae develop. "Once the angle has scar tissue present for too long, even if you can physically peel back the scar tissue, the trabecular meshwork may not be functioning properly," he said.

Moving on to trabeculectomy

Despite efforts to do cataract surgery and provide ACG patients relief, there are always going to be times when trabeculectomy is necessary. "If the anterior angle is synechially closed for more than 270 degrees, removing the lens may be insufficient to control the IOP and prevent glaucomatous progression," Dr. Bell said. A trabeculectomy may do a better job of controlling the IOP in those patients, he said, adding that if done in a phakic eye, it should be done with an iridectomy. "You want to perform that as well to remove the pupillary block component of angle closure. Otherwise, you'll make a hole in the sclera and the patient is still going to be at risk of an acute attack," he said.

Dr. Brown said that ACG patients with particularly high pressures may need a trabeculectomy but even then, he usually tries cataract surgery first. It goes back to tempering patient expectations, he explained. "You have to tell the patient there's a chance the cataract surgery might not work and that you'll have to do a trabeculectomy next week. You can't tell patients that the cataract surgery will always work. You have to say this is something that may help, but if it doesn't, we have a next step and we'll have to do it quickly," he said.

References

1. Friedman DS, Vedula SS. Lens extraction for chronic angle-closure glaucoma. Cochrane Database Syst Rev. 2006;19:CD005555.

2. Emanuel, ME, Parrish RK II; Gedde SJ. Evidence-based management of primary angle closure glaucoma. Curr Opin Ophthalmol. 2014;25:8992.

Editors' note: The physicians have no financial interests related to their comments.

Contact information

Bell: nbell@cizikeye.org
Brown: reaymary@comcast.net
Friedman: friedman@jhu.edu

Making the case for cataract surgery in angle closure glaucoma patients Making the case for cataract surgery in angle closure glaucoma patients
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