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A Schlemm’s canal scaffold reduces intraocular pressure in open angle glaucoma when placed in combination with cataract surgery: one year results from a prospective, multicenter, controlled, randomized clinical trial

Session Details

Session Title: Glaucoma

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

Paper Time: 17:46

Venue: Elicium 2 (First Floor)

First Author: : J.Garcia-Feijoo SPAIN

Co Author(s): :    N. Pfeiffer   J. Larrosa   A. Fea   J. Martinez de la Casa   P. de Waard   O.

Abstract Details

Purpose:

The objective of this study is to determine if a nitinol scaffold placed ab interno within Schlemm’s Canal reduces intraocular pressure (IOP) compared to cataract surgery (CS) alone in patients with cataract and open angle glaucoma (OAG).

Setting:

Reducing IOP in OAG by dilating Schlemm’s canal with a micro-scaffold offers several benefits including reduced dependence on IOP lowering medications, avoiding the difficulties inherent with medication compliance, and lowered risk of disease progression. CS provides a convenient setting to introduce such a device. However, the IOP lowering effect of the device alone is difficult to assess in single arm case series, since CS has been shown to reduce IOP by itself. Further, post-operative introduction of hypotensive medication further confounds IOP assessments. Therefore, a novel prospective, randomized study design was employed in this study. This study controls for the IOP lowering effect of cataract surgery through the randomization process, and for post-operative medication use by employing pre-operative and terminal wash out of hypotensive medications. The study was conducted at 7 European study centers in Spain, Germany, Italy, and the Netherlands.

Methods:

Subjects had to have a visually disabling age related cataract and open angle glaucoma. To reduce risks associated with wash out, only moderate glaucoma severity was included. Prior to surgery, patients discontinued ocular hypotensive medications for 14-28 days depending on the class of medication (wash out). At the completion of wash out, mean diurnal IOP (MDIOP) was determined by calculating the average of measurements taken at 8 am, 12pm and 4 pm using Goldman applanation tonometry (GAT). A MDIOP value of 22-36 mmHg was required for inclusion in the study. On the day of surgery, subjects were randomized to either cataract surgery (control arm) or cataract surgery + scaffold (test arm) according to a computer generated randomization sequence. Subjects randomized into the test arm received the study device, a nitinol scaffold (HydrusTM Microstent, Ivantis Inc., Irvine CA) implanted ab interno within Schlemm’s canal after phacoemulsification and IOL implantation. Subjects were not informed of their treatment assignment group. Follow up assessments were conducted at 1, 7 and 30 days, and 3, 6 and 12 months. IOP lowering medications were washed out prior to the 12 month visit, after which diurnal IOP was measured with GAT.

Results:

One hundred patients were randomized into study on the day of surgery. Study groups were well matched with regard to baseline characteristics including those pertaining to demographics, primary glaucoma diagnosis, visual acuity, VF loss severity, and pachymetry. Prior to wash out, mean IOP was18.9 mmHg with 2.0 mean medications/patient in the test group and 18.6 mmHg with 2.1 mean medications/patient in the control. After wash out, baseline mean diurnal IOP was 26.3 and 26.6 in the test and control groups respectively. Microstent implantation was successful, based upon predetermined criteria, in 48/50 subjects (96%). There were no serious adverse intraoperative events due to either cataract surgery or microstent implantation. At 6 months postoperatively, 88.9% of patients in the test group were medication free compared to 54.2% in the control group.

Conclusions:

Implantation of the Hydrus Microstent combined with cataract surgery is associated with a reduction of IOP lowering medications and a similar safety profile compared to cataract surgery alone.

Financial Interest:

... receives consulting fees, retainer, or contract payments from a company producing, developing or supplying the product or procedure presented, ... travel has been funded, fully or partially, by a competing company, ... travel has been funded, fully or partially, by a company producing, developing or supplying the product or procedure presented, ... research is funded, fully or partially, by a competing company, ... research is funded, fully or partially, by a company producing, developing or supplying the product or procedure presented, ... receives consulting fees, retainer, or contract payments from a competing company