The iStent inject Trabecular Micro-Bypass System is used at the time of cataract surgery to lower pressures in patients with glaucoma. It is made by Glaukos, the company that also makes the original iStent Micro-Bypass Stent. The main difference between the iStent inject and the original iStent is that with the iStent inject, two stents are utilized, whereas the original iStent only uses one stent. The iStent inject is also significantly smaller, with the largest dimension only measuring 360 μm (or 0.360 mm) long.
Glaucoma is a medical condition where the pressure inside the eye is too high, leading to progressive optic nerve damage. Open angle glaucoma, the most common form of glaucoma, is essentially a backing-up of fluid due to a drain that has become increasingly clogged. The main drain in the eye is called the trabecular meshwork.
Two stents are placed in the trabecular meshwork in different locations, creating two open passageways though this clogged drain. The head and thorax of the stent are buried in the trabecular meshwork, and only the flange is exposed (see image). The central inlet allows fluid to easily bypass the trabecular meshwork, and exit the side flow outlets. This, in turn, results in a lower intraocular pressure.
The FDA has approved the iStent inject to be used in patients with mild to moderate staged glaucoma, and only in conjunction with cataract surgery. The iStent inject is not FDA approved to be placed in patients who have already had cataract surgery, or do not need cataract surgery.
The advantages of the iStent inject are that it is so small that the patient cannot feel it or see it when looking in the mirror. It does not require a separate surgical incision and is well-tolerated. This Minimally Invasive Glaucoma Surgery (MIGS) is not an aggressive procedure, but with minimal risks, can make the difference if intraocular pressures are borderline controlled.
If you have glaucoma and need cataract surgery, it is definitely worth considering. Ask one of the doctors at the San Jose Eye Institute about the iStent inject, or any other MIGS devices.