Experimental study of cartilage setons.

Approximately 10 to 20 per cent. of primary external fistulizing procedures fail to effect long-term reduction in intraocular pressure (Nadel, I966).Because of this failure rate, the introduction of foreign materials including silk sutures, gold wires, and hairs to main- tain patent sclerostomies has been attempted (Rollet and Morean, 1906; Zorab, I912; Mayon, I912).A conductive seton was introduced by Stefansson (I925), who used a tube to connect the anterior chamber and subconjunctival space.Recently, newer plastics and silicone setons have been used in experimental filtration procedures (Bietti, I955; La Rocca, I962; Ellis, I960; Richards and Van Bijsterveld, I965).Their advantage has been the very slight foreign body reaction, but as with other foreign materials, there is still a tendency for the seton to slip into the anterior chamber or to be extruded from the wound (Ellis, I960).The current investigation was designed to produce an experimental seton model in rabbits, using tubes fashioned from autogenous rib cartilage.Since this substance should be well tolerated and integrated into surrounding tissues, the problems of rejection and slippage should be negligible.In addition, the production of successful filtering blebs by this method might provide an experimental tool to explore the histopathology and mech- anism of bleb production and failure. Material and methodsAlbino and pigmented rabbits were anaesthetized with intravenous pentobarbitone.Fur was clipped from the chest, the underlying skin was sterilized, and I.5 cm.lengths of either eighth or ninth rib