1. Kimberly V. Miller, MD Jeremy B. Wingard, MD Michael J. Pokabla, MD Korinn M. Strunk Jennifer L. Gray, PhD Rocio Bentivegna, MD Robert J. Noecker, MD, MBA The authors of this poster received research funding from National Institutes of Health CORE Grant P30 EY008098, Eye and Ear Foundation of Pittsburgh, and Research to Prevent Blindness, New York, NY. The authors have no conflicts of interest. UPMC Eye Center, Department of Ophthalmology University of Pittsburgh School of Medicine Ophthalmology & Visual Science Research Center The Eye & Ear Institute millerkv@upmc.edu

2.  To examine the fit of the Ex-PRESS mini-shunt glaucoma filtration device in incisions made by 25-gauge and 27-gauge needles using human cadaver eyes and scanning electron microscopy.

3.  A human cadaver eye was obtained from autopsy and marked at the superior position.  The anterior chamber was pressurized using viscoelastic.  Two incisions were created with each of two different types of needles – 25-gauge and 27-gauge, at 4 different clock hours, through the trabecular meshwork.  Four Ex-PRESS glaucoma filtration devices were inserted into the incisions using the standard inserter.  The eye was then sectioned and preserved in glutaraldehyde and PBS buffer. Scanning electron microscopy was then performed on each section to image the overall fit of the mini shunt in the incision.

4. Two mini shunts were not inserted entirely into the anterior chamber – one with a 25-gauge needle incision and one with a 27-gauge needle incision. Of the remaining mini shunts, there was no discernible difference in fit between the two incision sizes. Both mini shunts appeared to fit closely into the incision with very minimal gap noted around the edges of the devices, whether the incision was created with a 25-gauge needle or 27-gauge needle (pictured on next slide).

5. 27-gauge incision

6.  There was no difference in the fit of the Ex- PRESS mini shunt glaucoma filtration devices with a 25-gauge or 27-gauge needle incision as examined by scanning electron microscopy.  This effect may be due to the flange of the device being larger than the diameter of either incision.