Glaucoma valve implantation viable method for IOP control in PKP eyes

Implantation of a proprietary glaucoma valve (Ahmed Glaucoma Valve, New World Medical) is an effective method for managing refractory glaucoma in eyes undergoing penetrating keratoplasty (PKP) or with an existing corneal graft, according to results of a retrospective review.

Key Points

Fort Lauderdale, FL-Implantation of a proprietary glaucoma valve (Ahmed Glaucoma Valve, New World Medical) is an effective method for managing refractory glaucoma in eyes undergoing penetrating keratoplasty (PKP) or with an existing corneal graft, reported researchers from the University of Nottingham here at the annual meeting of the Association for Research in Vision and Ophthalmology.

"An aqueous drainage device, such as the [glaucoma] valve, may especially be considered to manage glaucoma in eyes undergoing PKP if traditional filtering surgery with adjunctive antimetabolite is likely to be unsuccessful or has failed or to manage refractory glaucoma associated with PKP," said Arun Lakshmanan, MD, affiliated with the Department of Ophthalmology and Visual Sciences, University of Nottingham, United Kingdom. Harminder S. Dua, MD, professor of ophthalmology, was the senior author of the project.

"In our retrospective review of such patients with a mean follow-up of 32 months, we found the overall success rate of valve implantation was 65%. This outcome was comparable to other published results," Dr. Lakshmanan said.

At last follow-up, BCVA ranged from light perception to 6/9. IOP was significantly reduced from 31 mm Hg at baseline to 15.7 mm Hg, and that benefit was accompanied by a significant reduction in glaucoma medication use from a mean of three medications per patient to 1.78.

Surgical success was defined as IOP <22 mm Hg and >5 mm Hg at the past two visits with or without glaucoma medications, along with BCVA of light perception or better, absence of any devastating complications (e.g., choroidal hemorrhage), and without any additional glaucoma surgery or valve removal. The 11 eyes that achieved surgical success included four of seven eyes (57%) in the group that underwent valve implantation after or simultaneously with PKP and seven of 10 eyes (70%) that had valve implantation for glaucoma developing after PKP. The rate of surgical success was not significantly different between the two groups, and a significant reduction from baseline IOP and in glaucoma medication usage was achieved in both groups.

Complications occurred intraoperatively in four eyes, including conjunctival buttonholing in three eyes and vitreous hemorrhage in one eye. The most common postoperative complication was valve occlusion (five eyes, 29.4%). Also, tube exposure with leakage occurred in two eyes (11.8%).

"Good control of postoperative inflammation may help to reduce the risk of valve occlusion," Dr. Lakshmanan said.

Among the six eyes in which surgery was considered a failure, three underwent valve replacement, one required glaucoma valve revision, one had uncontrolled IOP, and one eye became phthisical.