In vivo study comparing an X-shaped polymethylmethacrylate and a cylindrical collagen implant for deep sclerectomy.

BACKGROUND: Study in vivo characteristics of a polymethylmethacrylate (PMMA) implant compared to the standard cylindrical collagen implant for deep sclerectomy (DS). DESIGN: Six-month comparative study. SAMPLES: Twenty eyes of ten rabbits. METHODS: Eyes were randomized to have DS with PMMA implant in one eye and collagen implant in the opposite eye. The growth of the new subconjunctival drainage vessels was assessed by combined fluorescein and indocyanin green anterior segment angiography; intrascleral and subconjunctival blebs were imaged by ultrasound biomicroscopy (UBM). At six months, outflow facility (C) was measured by anterior chamber perfusion and portions of one side of the DS were compared to portions on the 180° opposite side and native sclera on histology. RESULTS: The mean IOP preoperatively and at one, four, twelve, and twenty-four weeks was comparable in both groups (P > 0.1). UBM showed a statistically insignificant quicker regression of the subconjunctival bleb as well as a durable intrascleral lake in the PMMA group (P > 0.05). New drainage vessels were initially observed one month after surgery; they were more numerous in the PMMA group on angiographic and histological findings at 6 months (P < 0.05). The mean C increased significantly after surgery compared to preoperative values (P < 0.05) and no difference was observed between the implants (0.24 ± 0.06 µl/min/mmHg [PMMA] and 0.23 ± 0.07 µl/min/mmHg [collagen implant]) (P = 0.39). CONCLUSIONS: Deep sclerectomy performed with PMMA or collagen implants showed similar IOP lowering effects, outflow facility increase, and degree of inflammatory reaction.

Outcomes after Descemet stripping endothelial keratoplasty in glaucoma patients with previous trabeculectomy and tube shunt implantation.

PURPOSE: To describe the incidence of intraoperative and postoperative complications and visual outcomes in eyes with previous penetrating glaucoma surgery undergoing Descemet stripping endothelial keratoplasty (DSEK). METHODS: A retrospective review of the first 227 cases of DSEK performed by 2 surgeons at a single institution. Data were collected regarding the performance of concurrent ocular procedures, intraoperative complications, postoperative visual outcomes, and postoperative complications, including primary graft failure, donor dislocation, endothelial rejection, and intraocular pressure (IOP) elevation. RESULTS: Fifty-six of the 227 DSEK procedures were performed in 52 eyes with previous trabeculectomy and/or tube shunt implantation. The percentage of procedures performed in eyes with and without a history of penetrating glaucoma surgery that resulted in primary graft failure (5.4% vs. 4.1%; P = 0.71) and donor dislocation (12.5% vs. 15.2%; P = 0.83) were not statistically significantly different. Additionally, the endothelial rejection rate was not significantly different between cases performed in eyes with (1/19.2 eye-years) and without (1/20.1 eye-years) a history of glaucoma surgery (P = 0.99). The incidence of elevated IOP (≥ 25 mm Hg) after DSEK was the highest in eyes with medically controlled glaucoma (47.4%), followed by eyes without a history of glaucoma (18.3%), and was the lowest in eyes with previous glaucoma surgery (11.5%). Postoperative corrected distance visual acuity was improved over the preoperative corrected distance visual acuity in 81%, 95%, and 88% of eyes with previous glaucoma surgery, medically controlled glaucoma, and no glaucoma, respectively. CONCLUSIONS: DSEK is an effective procedure to improve vision in the majority of eyes with advanced glaucoma after trabeculectomy and/or tube shunt implantation. The incidence of postoperative complications, such as donor dislocation, primary graft failure, and endothelial rejection, is not significantly higher in eyes with a history of glaucoma surgery before DSEK. Because almost 50% of eyes with medically controlled glaucoma before DSEK experienced IOP elevation after surgery, careful monitoring of the IOP after DSEK is especially important in this patient population.