making a relieving slit (Sherwood slit) in the occluded tube with a 20G corneal/scleral knife (1.3mm V-Lance®).
These surgical techniques, which are carried out under an operating microscope, have been shown to improve success rates and reduce the risk of complications of Molteno glaucoma implant surgery (13, 16). The occluding suture temporarily blocks the flow of aqueous from the eye while the drainage bleb starts to heal, an approach called 'delayed drainage'. At the same time the relieving slit allows aqeous to escape if the IOP gets high while waiting for the polyglactin suture to dissolve. Despite the challenges of working though a microscope, the trainees learned quickly and seemed delighted by their new mastery of the three skills.
V-Lance® is a trade mark of Novartis.