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One and two year follow-up of a novel minimally invasive drainage implant: the InnFocus MicroShunt™

Session Details

Session Title: Glaucoma

Session Date/Time: Monday 07/10/2013 | 17:00-18:34

Paper Time: 18:14

Venue: Elicium 2 (First Floor)

First Author: : J.Batlle DOMINICAN REPUBLIC

Co Author(s): :    P. Palmberg              

Abstract Details

Purpose:

The InnFocus MicroShunt (Miami, FL), formerly called the MIDI Arrow, consists of a very flexible tube made from poly(styrene-block-isobutylene-block-styrene) ("SIBS") with planar fins, located approximately halfway its length that serve to prevent the device from migrating into the anterior chamber and as a "stopper" to prevent peri-annular leakage. The lumen of the device is approximately 70 µm in diameter and serves as a flow restrictor to prevent hypotony and to dampen pressure spikes. The InnFocus MicroShunt shunts aqueous humor from the anterior chamber to a sub-conjunctiva/sub-Tenons flap. The purpose of this study is to evaluate the IOP lowering effects of the InnFocus MicroShunt™ used either alone or in combination with phacoemulsification for a period of two years.

Setting:

The clinical study was performed at the Centro Laser, Santo Domingo, Dominican Republic. One surgeon (JB) performed 19 of the 21 implantations.

Methods:

Single site, prospective non-randomized study of 21 eyes in 21 patients; 13 MicroShunts alone and 8 combined with phacoemulsification. The procedure is as follows: a fornix based sub-conjunctival/sub-Tenons capsule flap is formed over a quadrant and about 8 mm deep. Three Lasik shields soaked in 0.4 mg/mL MMC are placed in the pouch for 3 minutes and then rinsed out with > 20 mL of buffered sterile saline. A half thickness scleral pocket approximately 1mm wide x 1mm in length is made 3 mm from the limbus with a flat 1 mm wide x 1 mm long angled knife blade. A 25 gauge needle is advanced through the scleral pocket and into the anterior chamber bisecting the angle formed between the iris and cornea. The InnFocus MicroShunt is fed through the needle tract with a forceps and the fins on the shunt wedged into the 1.0 mm wide scleral pocket. Flow of aqueous humor through the MicroShunt is confirmed. The distal end of the device is tucked under the sub-conjunctival/sub-Tenon’s lap which is closed with multiple interrupted 10-0 nylon sutures on a spatula needle.

Results:

All but one of the patients were of Afro-Caribbean descent. The average medicated baseline IOP was 23.9 ± 5.4 mmHg (n=21). The number of medications/patient prior to surgery was 2.3 ± 0.9. The average IOP dropped 56% to 10.6 ± 2.8 mmHg (n=21) and 52% to 11.4 ± 3.0 mmHg (n=17) at 1 and 2 years, respectively. The success rate, measured by dropping IOP by ?20% without surgical intervention, was 100% (21/21) and 94% (16/17) at 1 and 2-years, respectively. The percent of patients with IOP ? 14 mmHg at one and two years is 90% and 88%, respectively. The percent of patients totally off of glaucoma medication was 90% and 86% with the number of medications/patient being 0.2 and 0.5, respectively. There were two cases of transient hypotony and two choroidal effusions which cleared spontaneously. There were no long-term sight-threatening adverse events. All eyes except one showed a bleb thereby indicating patency of the tube. The one eye that did not show a bleb had an IOP of 10 mmHg indicating functionality. There was only one case that required needling of the bleb. There were no other interventions performed within the first two years.

Conclusions:

The InnFocus MicroShunt effectively lowered IOP by 56% and 52% with 90% and 88% of patients achieving IOP of ? 14 mmHg at one and two years, respectively. These low pressures suggest from the AGIS Study that there will be no progression of vision loss in these eyes. Results are similar when implanted alone or in combination with phacoemulsification without serious long-term adverse events. The premise behind the design of the InnFocus MicroShunt is that in order to reliably achieve IOP less ? 14 mmHg in the majority of patients, aqueous needs to bypass not only the trabecular meshwork and Schlemm’s Canal but also the more distal episcleral veins. Shunting from the anterior chamber to a sub-conjunctiva/sub-Tenons pouch, were aqueous has the ability to diffuse through the microcysts of the conjunctiva and into the tear film, effectively drops IOP to these low levels. The simplicity of use and ease of follow-up will provide a simple and effective replacement for trabeculectomy and may become the treatment of choice for patients who have failed at least one glaucoma medication.

Financial Interest:

NONE