Tissue Reactivity to, and Stability of, Glaucoma Drainage Device Materials Placed Under Rabbit Conjunctiva

Purpose: To evaluate tissue reactivity to, and the stability of, glaucoma drainage device materials placed under rabbit conjunctiva in vivo. Methods: Disks (diameter, 3 mm; thickness, similar to 0.3 mm) fabricated from poly(styreneblock-isobutylene-block-styrene) (SIBS), silicone, stainless-steel, or glutaraldehyde crosslinked collagen (GACLC) were inserted under rabbit conjunctiva. Conjunctival and scleral sections obtained at 4, 8, and 12weeks after surgerywere immunostained for alpha-smooth muscle actin (SMA). The ratio of the maximum thickness of the a-SMA-positive conjunctiva to the scleral thickness (alpha-SMA/S ratio) was calculated. The in vivo stability of the drainage devices at 12 weeks after insertion was evaluated. Results: The mean alpha-SMA/S ratios of the SIBS and silicone groups were lower than that of the stainless-steel group at 4weeks after surgery (P< 0.05), and that of the SIBS group was lower than that of the GACLC group (P < 0.05). The ratios at 8 weeks after surgery were lower in the SIBS and silicone groups than in the GACLC group (P< 0.01). The ratios at 12 weeks after surgery were lower in the SIBS and silicone groups than in the GACLC group (P < 0.05). The surface areas of GACLC disks explanted from conjunctivae were significantly lower than that of intact disks (P < 0.01). Conclusions: SIBS and silicon were highly biostable and exhibited less tissue reactivity than GACLC in vivo.