Istent

iStent is a micro-invasive glaucoma surgery (MIGS) device designed to improve drainage of aqueous humor from the anterior chamber into Schlemm's canal, thereby reducing intraocular pressure. It is typically implanted through a minimally invasive approach during cataract surgery, when the eye is already exposed to a surgical platform.

The original iStent is a tiny, ab interno stent made of biocompatible material and is inserted through a clear corneal incision using gonioscopic visualization. A related variant, iStent Inject, consists of pre-loaded stents that deliver two implants in a single procedure to enhance outflow. Both devices aim to bypass the trabecular meshwork, creating a direct path for fluid to exit into Schlemm's canal.

Indications for iStent generally involve adults with mild to moderate open-angle glaucoma who are undergoing cataract surgery and seek additional reduction in intraocular pressure or a decreased need for glaucoma medications. It may be chosen as part of a cataract procedure to achieve modest IOP lowering with a favorable safety profile compared with more invasive glaucoma surgeries.

Procedure and outcomes: the implantation is performed ab interno through a corneal incision, with placement into Schlemm's canal under gonioscopic visualization. In clinical practice, iStent can modestly reduce IOP and reduce the number of glaucoma medications, particularly when used in combination with cataract extraction. Effect sizes vary among individuals.

Safety and limitations: common adverse events are usually mild and transient, such as conjunctival redness, temporary inflammation, or brief IOP fluctuations; device malposition is rare and serious complications are uncommon. iStent is one option within the MIGS category and is not typically used as a standalone treatment for advanced glaucoma.