Phacotrabeculectomy success similar in PACG, POAG

The success rate of single-site phacotrabeculectomy without the use of mitomycin C was similar in eyes with primary angle-closure glaucoma and eyes with primary open-angle glaucoma, a study found.

Previously, data on the safety and efficacy of phacotrabeculectomy in treating primary angle-closure glaucoma (PACG) vs. primary open-angle glaucoma (POAG) were lacking.

Harsha Laxmana Rao, MD, DNB, the lead author, told Ocular Surgery News that the significant result of the study was the similarity of success rates of phacotrabeculectomy in PACG and in POAG because PACG eyes are thought to be difficult cases to operate and are associated with bad outcomes.

“The surgery is basically tough in these eyes,” he said. “Pupils don’t dilate well, and the zonules are weak because of a higher intraocular pressure in PACG eyes. These factors made a lot of surgeons think that the outcomes of phacotrabeculectomy in PACG eyes are bad compared to the outcomes of phacotrabeculectomy in POAG eyes. This is what we tried to look at.”

PACG is highly prevalent in Southeast Asia and poses a high risk of vision loss, the study authors said.

“Angle-closure glaucoma is basically a very significant disease in this part of the world,” Dr. Rao said, noting that it accounts for almost half of the primary glaucoma cases seen in clinics in that region.

Study results were published in the Journal of Glaucoma.

Patients and methods

Researchers evaluated the records of 71 eyes of 63 patients with PACG and 72 eyes of 57 patients with POAG. All eyes underwent single-site phacotrabeculectomy without MMC at their center between 2001 and 2005.

All patients underwent Goldmann applanation tonometry, gonioscopy, dilated stereoscopic evaluation of the optic nerve and visual field evaluation. Patients with PACG underwent laser iridotomy before the dilated examination.

For statistical purposes, complete success was defined as attainment of IOP less than 21 mm Hg without glaucoma medications or additional surgery. Qualified success was defined as achievement of IOP less than 21 mm Hg with or without medications.

Mean follow-up was 38.7 months for the PACG group and 41.7 months for the POAG group; minimum follow-up was 12 months.

Lens removal in PACG

In the PACG group, 72.1% of patients experienced complete success, compared with 56.1% of patients in the POAG group. Qualified success was achieved in 87.4% of PACG patients and 92.8% of POAG patients. Differences in complete and qualified success rates were not statistically significant.

PACG eyes achieved statistically significantly greater IOP reduction and required fewer postoperative medications than the POAG eyes (both P = .03).

Investigators attributed elevated IOP in PACG eyes to greater lens volume in relation to the overall size of those eyes. Angle widening after lens removal most likely allowed better IOP control in the PACG eyes.

“The removal of the lens was probably a very significant contributor to the increased reduction in intraocular pressure,” Dr. Rao said. “We thought that removal of the lens was itself causing a certain amount of intraocular pressure reduction, and this was the reason for the mean intraocular pressure reduction being more in PACG [eyes].”

Overall results showed statistically significant reductions in IOP and number of medications and significant improvement in best corrected visual acuity in both the groups (all P < .01).

Complications, future study

PACG eyes had more complications than POAG eyes, but the difference was not statistically significant, the authors said.

“This is one of the things that we wanted to emphasize — not just good outcomes, but even the complication rate is comparable to that of POAG eyes,” Dr. Rao said.

For example, two eyes in each group had posterior capsular rent and one eye in each group had bleb leaks. Two eyes in the PACG group and no eyes in the POAG group had shallow anterior chamber, choroidal detachment and hypotony, the authors said.

Future analysis will involve outcomes of phacotrabeculectomy with MMC.

“We also have a good number of eyes where mitomycin C was used, but we did not collect information on these eyes,” Dr. Rao said. “[We are] trying to see if mitomycin C use is any better in these eyes compared to not using it. … You can actually use it with caution in a certain group of eyes because MMC can improve results.” – by Matt Hasson

Reference:

• Rao HL, Maheshwari R, Senthil S, Prasad KK, Garudadri CS. Phacotrabeculectomy without mitomycin C in primary angle-closure and open-angle glaucoma. J Glaucoma. 2011;20(1):57-62.

• Harsha Laxmana Rao, MD, DNB, can be reached at L.V. Prasad Eye Institute, L.V. Prasad Marg, Banjara Hills, Hyderabad 500034, Andhra Pradesh, India; 91-40-3061-2620; fax: 91-40-2354-8271; e-mail: harshabl@rediffmail.com.
• Disclosure: Dr. Rao has no financial interest in any products used in the study.