Posters

Comparison of aqueous outflow following implantation with Hydrus Microstent or iStent Inject

Poster Details

First Author: C.Orlich COSTA RICA

Co Author(s):    C. Orlich                    

Abstract Details

Purpose:

Two different Schlemm’s Canal stents have been approved by FDA. Both devices demonstrated reduction of IOP compared to cataract surgery alone in separate randomized clinical trials. The purpose of this study is to provide a direct head-to-head comparison of increase in aqueous outflow immediately following implantation of the Hydrus Microstent and the iStent Inject, and to assess correlation with postoperative reduction in IOP

Setting:

Prospective, randomized, controlled study. Patients with visually significant cataract and mild to moderate primary open angle glaucoma were recruited. Eyes with history of other significant ocular disease or prior intraocular surgery were excluded. Eyes were randomized 1:1 to receive either Hydrus or Inject.

Methods:

All surgeries were performed by a single surgeon certified in both procedures. After successful implantation of the stent, 0.5 ml of trypan blue dye was injected into the anterior chamber at a constant rate and video recording was made of the limbus in the treated hemisphere. The moment of peak trypan blue staining of episcleral vessels from each video was recorded as a still image. The images were graded by a panel of 3 independent reviewers masked to the treatment group. All glaucoma medications were discontinued following surgery. IOP, medication count and visual acuity were measured at baseline and postoperatively.

Results:

The study is ongoing, with enrollment of 20 eyes in each group. Trypan blue dye does not penetrate an intact trabecular meshwork and no dye was observed in episcleral vessels prior to stent implantation. The level of trypan blue staining was graded on a scale of 0-4 and reflects the extent of dye penetration into the episcleral vessels and the number of limbal clock hours with stained vessels. Preliminary observation indicates mean trypan blue staining score of approximately 3.7 following implantation of Hydrus and 1.6 following Inject. The amount of IOP reduction from baseline was positively correlated with the level of trypan blue staining.

Conclusions:

Trypan blue staining of episcleral vessels is a valid marker for demonstrating aqueous outflow from the anterior chamber, through Schlemm’s Canal and into the episcleral vessels. This study demonstrated greater level of aqueous outflow and postoperative IOP reduction with the Hydrus Microstent, compared to the iStent Inject.

Financial Disclosure:

research is funded, fully or partially, by a company producing, developing or supplying the product or procedure presented, travel has been funded, fully or partially, by a company producing, developing or supplying the product or procedure presented