LAUSR

Hypotony is a major issue related to valveless glaucoma drainage devices (GDDs) like the Baerveldt glaucoma implant (BGI) or Aurolab Aqueous Drainage Implant (AADI). Pre‐emptive measures for early flow restriction are well described and widely practiced in these types of GDDs, mostly in the form of occlusive temporary polyglactin ligatures and/or use of the intra‐luminal ripcord stenting technique. However, once the occlusive ligature autolyzes at around 5–6 weeks, during which a thin plate capsule formation occurs providing resistance to aqueous outflow, there remains a small risk of hypotony thereafter, of 0% to 4.4%.[1,2] Though rare, the consequences of this persistent hypotony can be devastating with shallow anterior chamber (AC), choroidal effusion, hypotony maculopathy and decrease in vision, which may become permanent if prompt management is not instituted. This late hypotony can at times be very difficult to manage, and strategies include either filling up the chamber with one or several injection/s of ophthalmic visco‐surgical devices or even C3F8 gas, or by manipulating the tube with secondary external ligatures or intra‐luminal stenting. External ligatures include those with a repeat of the non‐permanent polyglactin occlusive ligature or partial occlusion with permanent 9/0 nylon or prolene. The latter produces inadequate indent, and several ligatures may have to be employed, as described elsewhere for valved tubes.[3] On the other hand, 3/0, 4/0, or 5/0 of the same sutures have also been described for secondary intra‐luminal stenting. Of late, 3/0 polyamide (Supramid S. Jackson Inc., Alexandria, VA, USA) is gaining popularity worldwide due to its favorable properties of being firm enough for ab interno stenting. It later swells up to occupy the entire lumen, yet as it is semi‐porous, it allows aqueous to pass through,[4] unlike nylon and prolene sutures which are rigid. Some authors have also described the use of the gelatin stent XEN‐45 microns (not yet available in India) inserted ab externo into the anterior chamber.[5]