Glaukos iStent Glaucoma Program at Vance Thompson Vision

Glaukos iStent Top Line

Minimally Invasive Glaucoma Surgery (MIGS) procedures are creating new options for patients with mild to moderate glaucoma. These procedures have a higher safety profile with fewer complications and a more rapid recovery time than other invasive techniques. They have been shown to be effective in decreasing IOP as well as a patient’s need for medications, which is important given a typically low compliance rate for medication adherence. The Glaukos iStent was FDA approved in 2012 in conjunction with cataract surgery and is the smallest medical device known to be implanted in the human body. It was created to serve as a bypass through the trabecular meshwork to allow physiological outflow and lower IOP. The iStent can be used in conjunction with cataract surgery or stand alone, although deemed off-label, for patients with mild to moderate glaucoma.

What is the Procedure?

The iStent Trabecular Micro-Bypass Stent (Glaukos, Laguna Hills, CA) received FDA approval in 2012. The device is a heparin-coated, non-ferromagnetic titanium stent with a snorkel shape to facilitate implantation. The device is placed using a single-use, sterile inserter through a 1.5mm corneal incision. The applicator is inserted into the anterior chamber and across the nasal angle. The pointed tip allows penetration of the trabecular meshwork and insertion into Schlemm’s canal and three retention arches ensure that the device will be held in place. The iStent itself is the smallest FDA approved device, measuring at 0.3mm in height and 1mm in length. iStent implantation at the same time as cataract surgery has a greater safety profile compared to traditional filtration surgeries in combination with cataract surgery. Patients that undergo traditional filtration surgeries are at risk for complications, such as bleb leaks, bleb infections, or hypotony, which, are not a concern for patients implanted with the iStent.

When and Why Do It?

Indications and Candidacy

In patients with mild-moderate glaucoma with an IOP that has been unable to be controlled by medications or who have poor medication compliance, a Glaukos iStent appears to be a viable option. Clinical trials have shown there to be a significant decrease in IOP over periods of up to 24 months along with a significant decrease in medication usage. The procedure has maintained a high safety profile with minimal adverse effects. The Glaukos iStent can provide a method of treatment for glaucoma patients that decreases reliance on medications without the safety risks of more invasive procedures. Patients that are candidates are: - Patients with mild-moderate glaucoma, primary open-angle glaucoma, pseudoexfoliation glaucoma, or pigmentary dispersion glaucoma - Glaucoma is uncontrolled with maximum pharmacologic treatment or there are barriers preventing adequate medication dosing - Age greater than 18 - Patients with clinically significant cataract, as surgery may be performed simultaneously. All patients should have a pre-op comprehensive eye exam including gonioscopy and a detailed medical history. Contraindications: Relative contraindications for this procedure may include angle-closure glaucoma, secondary glaucoma, advanced glaucoma, previous glaucoma surgery, or severely uncontrolled IOP.

How is the Procedure Done?

Cataract extraction and IOL implantation occur first. The head is properly positioned to perform an adequate view of the angle anatomy with a gonio lens. A corneal incision is made and the anterior chamber is filled with viscoelastic. The iStent inserter is advanced across the anterior chamber and, with the magnified view of a gonioprism, the iStent is then implanted through the trabecular meshwork and secured into Schlemm’s canal. There is typically an egress of heme from Schlemm’s canal, indicating proper placement. At the end of the surgery, the corneal wounds are hydrated for a watertight seal as would be performed in cataract surgery alone; typically, no sutures are necessary.

CLICK HERE the watch a video of the iStent procedure.

Post-Op Care

Cataract extraction plus iStent

Drop-A-Day Approach: Dex-Mox-Ketor injection at conclusion of the cataract plus iStent procedure. The patient takes Ilevro, Prolensa or Bromsite one time a day for one month.

Standard Approach: Vigamox four times a day for one week, prednisolone acetate 1% four times a day for one week then two times a day for three weeks, Ilevro, Prolensa or Bromsite one time a day for four weeks.

iStent in a Pseudophakic Eye

Vigamox four times a day for one week, Ilevro, Prolensa or Bromsiteone time a day for four weeks.

Post-op follow-up care is one day, one week, one month, and three months. The addition or subtraction of patient’s glaucoma medications is done on a case by case basis. The severity of the glaucoma present and the level of IOP is considered when adding or subtracting glaucoma medications.

Complications

Placing a foreign object into the eye does introduce the potential risk of intraoperative complications, e.g., if the device is malpositioned and the tip becomes occluded by iris or if the device becomes dislodged. Postoperatively, there can be IOP spikes and hyphema. Also, because it is a fairly new procedure, it is considered experimental and not currently covered by many commercial insurances, although it does have excellent Medicare coverage. Preoperatively, candidates require a full glaucoma and cataract work up with ancillary testing (pachymetry, visual field, RNFL analysis, K readings, axial length, etc.). Blood thinners should be stopped preoperatively if possible. Post-op care is the same as traditional cataract surgery. Patients should be informed that their vision may be blurred for the first few days due to the mild bleeding during the surgery.