Comparison of Different Biomaterials for Glaucoma Drainage Devices<subtitle>Part 2</subtitle>

Abstract

Background: Inflammation associated with biomaterials may contribute to the failure of glaucoma drainage devices.Objective: To compare the inflammatory reaction associated with the insertion of Krupin silicone, Molteno polypropylene, and Acrosof end plates in the subconjunctival space of rabbits.Methods: Similar-sized glaucoma end plates made of 3 different biomaterials were sutured to the sclera in the superotemporal quadrant of the rabbit eye. Thirty eyes of 15 albino New Zealand rabbits were randomly assigned to the 3 groups. Conjunctival vascular hyperemia was graded in a masked fashion among the 3 groups. At the end of 3 weeks, the enucleated eyes were examined histologically and by scanning electron microscopy.Results: Molteno polypropylene was associated with more inflammation both in clinical observations and based on histological grading. Silicone and Acrosof were associated with less intense inflammation. One polypropylene end plate was extruded on day 21.Conclusions: Polypropylene appears to be more inflammatory than silicone. Flexible biomaterials appear to be less inflammatory than rigid ones.Clinical Relevance: Bleb failure following glaucoma drainage device implantation could be related to the biomaterial-associated inflammation. Choosing a biomaterial with the least inflammatory potential might enhance the success rate of the glaucoma drainage device.

In VitroFluid Dynamics of the Ahmed Glaucoma Valve Modified with Expanded Polytetrafluoroethylene

“…[10][11][12][13] This encapsulation reaction is similar to the tissue response observed around most polymer implants. 14,15 Fibrotic, minimally vascular capsule formation gradually increases outflow resistance from the drain and eventually results in increased intraocular pressure (IOP).…”

Comparison of polypropylene and silicone Ahmed® glaucoma valves in the treatment of neovascular glaucoma: A 2-year follow-up

“…13 Ayyala et al in an animal experimental study showed that polypropylene is more inflammatory than silicone. 14 In addition to valve material, other factors may influence the success rate after implant glaucoma surgery. Greater surface of the end-plate of the valve may be associated with lower IOP, still with the upper limit of the surface area beyond which the valve implantation will stimulate a greater inflammatory response.…”

Polypropylene vs silicone Ahmed valve with adjunctive mitomycin C in paediatric age group: a prospective controlled study

“…Experimental studies in rabbits have shown that polypropylene and other rigid biomaterials were associated with significantly more inflammation than silicone. 6,8 Law et al 9 compared the results of 50 silicone and 49 polypropylene AGVs in refractory glaucoma over a period of 12 months and showed that silicone AGVs resulted in lower IOPs with the difference between both groups being statistically significant at 3 months. However, more non-tube-related complications were encountered in the silicone group.…”

“…In experimental models of glaucoma drainage devices, silicone was associated with less inflammation and fibrosis compared with polypropylene. 7,8 It is postulated that the less the encapsulation around the explant, the less the resistance will be to aqueous flow, thus yielding better intraocular pressure (IOP) control and a longer term success of the device. 6 Most clinical studies comparing silicone to polypropylene AGVs have been retrospective studies on adult eyes and showed better or similar results with the silicone AGV.…”