Late drainage failure a risk in clear cornea trabeculectomy

DUNEDIN, New Zealand — Late failure of a clear cornea trabeculectomy can result in a dramatic intraocular pressure rise and subsequent vision loss, according to a retrospective record review performed here. The researchers indicated this type of late failure has been previously unreported.

Karl W. Whittaker, FRCOphth, and colleagues with the University of Otago Medical School identified patients who underwent clear cornea trabeculectomy at a local hospital and compared those patients who had late failure of drainage with those who had failure following traditional trabeculectomy. A clear cornea trabeculectomy attempts to allow fluid to pass between the anterior chamber and the subconjunctival space without intraoperatively disturbing the conjunctival tissue or Tenon’s tissue.

Late drainage failure occurred in three of 21 eyes following clear cornea trabeculectomy and 32 of 450 cases following conventional trabeculectomy.

Each case of failure in the clear cornea trabeculectomy group was associated with accelerated failure and a dramatic rise in intraocular pressure (IOP). Two of the three eyes also experienced consequent visual loss.

All cases of drainage failure in the conventional trabeculectomy group were associated with a gradual, less acute rise in IOP.

The study is published in the April issue of Clinical & Experimental Ophthalmology.