Survival analysis for success of Molteno tube implants

Aim-To apply survival analysis in assessing the long term outcome of Molten o tube implantation and to identify risk factors for failure. Methods-A retrospective, 10 year, consecutive case series study of 119 eyes that underwent implantation of a Molteno tube. The main outcome measures c onsidered were intraocular pressure (IOP), visual acuity, and complications . Results-A 30% or greater reduction in IOP was achieved in 68.9% of cases. H owever, the overall, "complete success" rate (IOP <22 mm Hg with no medicat ions) after a mean (SD) follow up period of 43 (33) months (range 6-120) wa s only 33.6% despite a fall in mean (SD) HOP from 38.2 (8.2) mm Hg to 20.1 (11.0) mm Hg. The "qualified success" rate (IOP <22 mm Hg with or without m edications) was 60.5%. Failure was most common in the first postoperative y ear but could occur after several years, the survival curve: having an expo nential shape. The only statistically significant risk factor for failure i dentified was pseudophakia, although eyes with neovascular glaucoma tended to fare poorly. Postoperative: IOP tended to be lower after double plate th an after single plate implantation. There was no significant difference in outcome based on age, sex, race, previous penetrating keratoplasty, or prev ious conjunctival surgery. Conclusions-In eyes at high risk of trabeculectomy failure, implantation of an aqueous shunt device should be considered. Pseudophakia should be consi dered an additional risk factor for failure. Early failure appeared relativ ely more common but long term follow up of all cases is recommended to ensu re adequate management of late failures.