Surface topographies of glaucoma drainage devices and their influence on human tenon fibroblast adhesion

This study was performed to investigate the surface topography of different glaucoma drainage devices and to determine the effects of surface roughness on cell adhesion of cultured human tenon fibroblasts.

The surface topography of four widely used devices (Ahmed FP7 and Ahmed S-2; New World Medical, Inc., Rancho Cucamonga, CA; Baerveldt BG101-350; Advanced Medical Optics, Irvine, CA; and Molteno S1; Molteno Ophthalmic Ltd., Dunedin, New Zealand) was investigated by scanning electron microscopy, and roughness was quantified by white-light confocal microscopy. Cells were grown for 72 hours on the surfaces of implants affixed to standard culture dishes. The cells were labeled with a fluorescent dye and detected by confocal laser scanning microscopy, while simultaneously imaging the surface reflectance. Collagen adsorption was quantified immunologically by using fluorescent beads coupled to a secondary antibody.

The root-mean-square roughness was 1.5 +/- 0.1 microm (mean +/- SE) for the silicone Ahmed model FP7 and 1.3 +/- 0.1 microm for the Ahmed with polypropylene base plate Ahmed model S-2. The Baerveldt was substantially smoother, with a mean roughness of 0.1 +/- 0.01 microm. The Molteno was the smoothest of all devices (0.07 +/- 0.01 microm). Cell adhesion was most prevalent on base plates with higher surface roughness, markedly less pronounced on the smoother base plates, and independent of collagen adsorption.

The most frequently implanted glaucoma drainage devices are of markedly different surface topography. Surface roughness appears to correlate with tenon fibroblast adhesion in vitro and also with the rate of occurrence of postimplantation hypertensive phase and failure due to fibrous encapsulation. Surface roughness may thus play a role in triggering excessive fibrovascular reactions. Smoother base plate surfaces may enhance the success rates of these devices.