Cataract extraction may have place in IOP lowering

Take-home

High IOP can be lowered substantially with combined cataract extraction and trabeculectomy.

By Lynda Charters; Reviewed by David S. Friedman, MD, MPH, PhD

Baltimore-Cataract extraction may have its place in managing certain patients with glaucoma, especially those in whom the IOP should be decreased by a few millimeters of mercury.

Patients with more elevated IOP may need a combined cataract extraction and glaucoma procedure. David S. Friedman, MD, MPH, PhD, discussed the evidence for managing glaucoma using cataract extraction.

“Cataract extraction recently has become very popular in the management of angle closure glaucoma [ACG],” said Dr. Friedman, director, Dana Center for Preventive Ophthalmology, and the Alfred Sommer Professor of Ophthalmology, Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore.

The crystalline lens has a role in ACG. Dr. Friedman explained that the more anteriorly displaced into the anterior chamber (lens vault) the lens is, the more likely a person has angle closure. The amount of lens vault, he noted, is a strong predictor of angle closure.

Clinical study evidence

A number of studies support cataract extraction for managing glaucoma.

“The key finding is that in the presence of lens vault removing the lens eliminates angle closure,” Dr. Friedman said. He cited a recent preliminary study that found that the greater the amount of lens vault, the greater the IOP reduction was after cataract extraction. Lens vault may ultimately predict which patients will respond to cataract extraction.

A Japanese study (Nonaka et al. Ophthalmology. 2005;112:974-979) showed that cataract extraction can affect the ciliary body position in plateau iris. The investigators showed that both angle closure decreased and the ciliary body moved farther back after cataract surgery.

In eyes with acute episodes of elevated IOP, an early study of this topic by Jacobi et al. (Ophthalmology. 2002;109:1597-1603) noted a substantial benefit of cataract surgery in these patients in whom the average IOP was 40 mm Hg.

“Eleven percent of eyes that underwent early phacoemulsification and cataract extraction required a later glaucoma surgery compared with 63% in eyes that only had laser iridotomy performed,” Dr. Friedman said. This promising result was later confirmed by Lam et al. (Ophthalmology. 2008;115:1134-1140) who carried out a randomized clinical trial in Hong Kong and showed that IOP is better controlled in those who have cataract surgery soon after an acute attack.

Cataract surgery for chronic primary ACG, according to Dr. Friedman, is not always the perfect solution, but some large IOP reductions can be seen.

“Identifying the patients who will benefit from cataract surgery alone will be addressed in ongoing studies,” he said.

Another study (Tham et al. Ophthalmology. 2008;115:2167-2173) that compared cataract extraction with combined cataract extraction and trabeculectomy found that patients in that study who had relatively low baseline  IOP who underwent phacoemulsification had less of a reduction compared with those who underwent the combined surgery and experienced greater IOP lowering.

Main points

“Cataract extraction clearly lowers IOP in primary ACG,” Dr. Friedman said.

The surgery also does so in patients with open-angle glaucoma (OAG); 1 year after surgery, patients with angle closure who had cataract surgery had an average decrease of about 1 to 1.5 mmHg and the need for medications also decreased.

A concern in patients with primary ACG is the occurrence of postoperative IOP spikes when cataract extraction alone is performed, because the patients have a compromised angle and aqueous outflow and are at risk for high IOP postoperatively.

There is uncertainty about removing clear lenses in patients with primary ACG.

“This is a discussion that needs to take place,” Dr. Friedman said. “There are risks to everything we do, and weighing them against the benefits of cataract extraction in these patients is part of the clinical decision-making process.”

Retinal detachment, endophthalmitis, and cystoid macular edema are possible adverse events related to cataract surgery, he noted.

The take-home message for ophthalmologists when managing patients with primary ACG and elevated IOP was that cataract extraction may be a consideration.

“If the IOP is not markedly high I believe that the patient has a chance that the surgery may lower the IOP sufficiently, cataract surgery is always my preference,” Dr. Friedman said. “However, if the IOP is too high and the concern is that they could not sustain an IOP spike, I recommend a combined cataract extraction and trabeculectomy. In patients with acute IOP elevations, the lens should be removed early.”

A new multicenter international clinical trial is on the horizon. The EAGLE Trial will assess the role of clear lens extraction in primary ACG compared with conventional management. The hope, according to Dr. Friedman, is that the trial will definitively answer the question about the role of early lens extraction in primary ACG.

David S. Friedman, MD, MPH, PhD

E: David.Friedman@jhu.edu

Dr. Friedman has no financial interest in the subject matter. This article is adapted from Dr. Friedman’s presentation during Glaucoma 2012 at the annual meeting of the American Academy of Ophthalmology.