Preserved corneal tissue may be superior for shunt tube coverage

This retrospective study found that glaucoma drainage implant shunt tubes had a lower rate of erosion when covered by glycerol-preserved cornea than when covered by pericardium.

They believe this to be the first study to directly compare corneal tissue to pericardium for glaucoma drainage implant coverage.

They reviewed the records of 262 patients at one university glaucoma service who underwent shunt procedures using either corneal tissue or pericardium to cover the tube. Median follow-up was 440 days for the cornea group and 331 days for the pericardium group.

Nine out of 101 patients (8.9 percent) in the pericardium-covered group experienced an erosion compared with three out of 161 (1.9 percent) in the cornea-covered group (P = 0.0125). The median time to shunt tube exposure was 252 days in the pericardium group and 440 days in the cornea group (P = 0.0017).

The study does have limitations, such as multiple surgeons using dissimilar patch graft materials and the use of single-thickness pericardium (whereas the use of double-thickness pericardium may reduce implant exposure).

The fact that pericardium has a long shelf-life used to be an advantage over corneal or scleral donor tissue as the latter had to be procured on the day of surgery from tissue banks. However, this no longer holds true as multiple other commercially available corneal and scleral patch products have a similarly long shelf life (such as the glycerol-preserved cornea used in this study).

It is my opinion that corneal patch grafts should be preferentially chosen over pericardium given the decreased rate of exposure, longer time to initial exposure, ability to perform laser suture lysis under the patch graft, and improved cosmesis.

Further studies comparing corneal patch grafts to other more commonly used patch grafts, such as scleral, would be interesting to further elucidate whether one patch material is clearly superior.