Study shows phaco alone may lower IOP in chronic angle-closure glaucoma

Preliminary results show phaco may not achieve the same level of IOP control as phaco-trabeculectomy, but it has fewer complications.

ByErin L. Boyle

Combined phacoemulsification and trabeculectomy surgery is frequently performed in patients with glaucoma and coexisting cataract. Recent studies have suggested that in chronic angle-closure glaucoma, removal of the lens alone can result in significant IOP reduction.

An ongoing randomized, controlled trial in Hong Kong is comparing the efficacy of lens extraction alone by phacoemulsification against the conventional combined procedure in patients with chronic angle-closure glaucoma and co-existing cataract. Preliminary data reveal that lens extraction alone results in significant improvements in IOP control and is associated with fewer complications and additional surgical interventions.

Clement C.Y. Tham, FRCS, and colleagues are conducting a study on phaco and trabeculectomy in chronic angle-closure glaucoma patients with coexisting cataract.

“As we all know nowadays, the incidence of chronic angle-closure glaucoma increases with age, and so the majority of patients with chronic angle-closure glaucoma have coexisting cataract,” he said. “In fact, cataract is probably an important causative mechanism in chronic angle-closure glaucoma.”

Three steps in management

Surgery is the last step in a three-step process of managing chronic angle-closure glaucoma, Dr. Tham said.

The first step is attempting to open all of the closed segments of the angle, which is the mechanism of increased IOP in angle-closure glaucoma, he said. The most commonly performed procedure is laser peripheral iridotomy, Dr. Tham said, because it eliminates the pupillary block and allows most of the angle to open.

He said argon laser peripheral iridoplasty is an effective tool to open the closure if there is still appositional angle closure after laser peripheral iridotomy.

“In a lot of these patients, even after laser peripheral iridotomy, the angle may remain appositionally closed to varying extent,” he said. “Under those circumstances, we normally proceed to perform argon laser peripheral iridoplasty to open up any persistent areas of closure, especially if there’s still raised pressures.”

If IOP is still uncontrolled after the closure is opened, the next step typically is topical medications, according to Dr. Tham. If maximally tolerated medications cannot control the IOP, then surgery is the last option.

Study results

Dr. Tham and colleagues are currently conducting a randomized, controlled study on lens extraction and trabeculectomy in chronic angle-closure glaucoma patients with coexisting cataract. Patients were randomized to receive either phaco alone or a combined phaco-trabeculectomy procedure. Patients who had more than 180° of synechial angle closure were on medications to control IOP, he said. All patients had visually significant cataracts.

The researchers aimed to recruit 150 patients in total, and they currently have more than 100 patients. Ninety-two have had more than 3 months of follow-up; 41 patients are in the phaco group and 51 are in the phaco-trabeculectomy group. The mean follow-up was approximately 12 months.

Dr. Tham said there was a significant reduction in IOP and the number of glaucoma drugs required in both treatment groups from the preoperative level throughout the follow-up period. Initially, the combined phaco-trabeculectomy group had better IOP control than the phaco group, but the difference decreased with longer follow-up.

Overall, the phaco-trabeculectomy group needed about 0.7 fewer glaucoma drugs than the phaco-only group over the whole follow-up period.

“Up to this point, it appears that the combined surgery seems to have a slight edge over cataract extraction alone in terms of IOP control,” Dr. Tham said. “Up to around 18 months, there seems to be a difference of around 0.7 drops between the two groups. But what is the price to pay for this advantage?”

He said additional surgical interventions were required to maintain the filtration bleb in the phaco-trabeculectomy group. Six cases required laser suture lysis, three required needling, two required additional subconjunctival 5-fluorouracil injections because of conjunctival congestion, and one required revision of the trabeculectomy because of overdrainage.

“Against this background, I have to stress that actually one case in the phaco-only group, which is around 2.4% of the cases in the phaco group, subsequently required trabeculectomy due to uncontrolled IOP,” he said.

For intraoperative complications, there was no statistically significant difference between the two groups, Dr. Tham said.

There was, however, a statistically significant difference in postop complications between the two groups. In the combined group, there was conjunctival leakage that required suturing, hyperemia, excessive anterior chamber inflammation, shallow anterior chamber, symptomatic giant bleb and hypotony.

For more information:

Clement C.Y. Tham, FRCS, can be reached at University Eye Center, Hong Kong Eye Hospital, 147K Argyle St., Kowloon, Hong Kong; +852-2762-3196; fax: +852-2816-7093; e-mail: clemtham@hkstar.com.

Erin L. Boyle is an OSN Staff Writer who covers all aspects of ophthalmology.