Minimally invasive glaucoma surgery (MIGS) has improved the treatment of glaucoma. The iStent from Glaukos is a MIGS technique that is an excellent treatment for glaucoma patients who are undergoing cataract surgery.
The iStent is implanted at the conclusion of cataract surgery through the same corneal incision. All cataract surgeons should learn this procedure. I recommend contacting the company to start the certification process, and here are some tips for the iStent.
Glaukos iStent
- Trabecular Micro-Bypass Stent: FDA approved 2012
- Material: Medical grade titanium with heparin coating
- Snorkel design: 1 mm length, 0.3 mm height, 120 micron lumen diameter, 2 orientations (right stent GTS100R; left stent GTS100L)
- Inserter: Disposable, preloaded, used to position or retrieve iStent
- Placement: Nasal into Schlemm’s canal
Patient Selection
- Adults with mild to moderate open angle glaucoma treated with ocular hypotensive medication who are undergoing cataract surgery
Equipment
Surgical Technique
- Nasal placement through temporal incision
- Inject intracameral miotic to deepen angle
- Inject viscoelastic to maintain the anterior chamber without overfilling
- Positioning to visualize trabecular meshwork (TM): tilt microscope at least 35 degrees towards surgeon and tilt patient’s head at least 35 degrees away from surgeon
- Visualize TM: increase microscope magnification to 10-12x, place gonioprism on cornea with viscoelastic, identify angle structures
- Hold iStent inserter with finger on release button and place inserter across anterior chamber, then apply gonioprism to cornea
- Move the iStent to the top third of the TM at a 15-degree angle, using the incision as a fulcrum rotate the inserter to engage the stent tip, gently penetrate the TM and slide the stent into Schlemm’s canal. There should be minimal to no resistance, and blood may reflux
- Tap the snorkel to position the heel into Schlemm’s canal
- Verify proper positioning with direct visualization and by assessing snorkel movement with gently nudging
- Remove viscoelastic, pressurize eye with BSS, and ensure watertight incision