A SIBS Micro Porous Corneal Filtering Device in the Rabbit Model

Abstract

 

Purpose:

 

To describe an experimental glaucoma implant using a Micro Porous Corneal Filtering Device ("MPCFD") made from porous SIBS to create a blebless aqueous pathway through the peripheral cornea.

 

Methods:

 

The MPCFD made of a thin porous disk (3.2mm diameter, 620µm thick) with a central porous dome (1.2mm diameter) protruding 200µm above and below the plane of the disk. The density of the porous device is 50% with the pores defining a tortuous path through the device with the intension of allowing fluid passage but limiting bacterial penetration. Two MPCFDs were fabricated as described above (Series A), 4 MPCFDs were fabricated with 4 symmetrically-spaced 400µm holes located in the disk brim to help promote tissue integration (Series B). Six NZW Rabbits were implanted: At 12 O’clock and at 1mm posterior from the limbus scleral flap was dissected with a spatula and 4 mm intrastromally into the thickness of the cornea. A 1.2mm hole was trephinated entirely through the cornea and the center of this tract. The MPCFD was placed through the tract with the bilateral domes protruding into the holes. The entry flap was closed with 7.0 Vicryl. Follow-ups at 1, 7, 14, 28, 60 days (to be carried out to 90), evaluated biocompatibility. Pachymetry and IOP were performed.

 

Results:

 

All operated eyes displayed severe corneal edema until POD 7, which slowly disappeared by POD 60. Vessel ingrowth began at POD 7-14 and then tapered off by POD 60. Associated with vessel ingrowth was a color change of the device from white to yellow and then back to white as the ingrowth subsided. At 60 days, one device totally extruded and in another device, the central dome was torn-off, presumably by rubbing of the eye by the rabbit. None of the remaining devices showed signs of infection.

 

Conclusions:

 

The SIBS Micro Pore Corneal Filtering Device, effectively lowered the IOP and maintained it low for 60 days without showing signs of infection. Ongoing work is in progress to prevent extrusions. The MPCFD provides an effective alternative blebless filtering device.  

 

Keywords: aqueous • cornea: stroma and keratocytes • cornea: stroma and keratocytes