Evaluation of the Krupin-Denver valve implant in normotensive and glaucomatous beagles.

The Krupin-Denver valve was implanted unilaterally in 2 normotensive and in 6 glaucomatous Beagles. The fellow eye of each dog had an external trabeculectomy. Before and after surgery, all dogs were evaluated serially by gonioscopy, biomicroscopy, tonometry, and tonography. The valve implant remained patent in 2 normotensive and in 2 glaucomatous Beagles throughout the 12 months of observation. Valve function was lost in 4 glaucomatous Beagles 4 to 6 weeks (3 dogs) and 6 months (1 dog) after implantation. Light microscopic and scanning electron microscopic evaluations of early loss of implant function revealed occlusion of the lumen and/or valve mechanism by inflammatory debris and cells. The late loss of valve function was related to chronic inflammatory response and fibrosis about the valve mechanism and tubing within the sclera.