Partial thickness corneal tissue as a patch graft material for prevention of glaucoma drainage device exposure

Abstract

BackgroundTo protect from erosion of the tube in glaucoma drainage device (GDD), the tube is covered by a biologic tissue which is roofed by the conjunctiva. Sclera, pericardium, dura mater and cornea are available as a patch graft. Drawbacks of some of these materials may include high cost and poor appearance. The purpose of this study is to report the long-term outcomes of partial thickness corneal grafts to cover the tube and prevent its exposure, in GDD surgeries.MethodsThis was a retrospective review of all patients who underwent Ahmed glaucoma valve implantation and had a minimum follow-up of 12 months. The tube was covered by a 300-micron partial thickness corneal graft taken either from a previous Descemet stripping endothelial keratoplasty procedure or cut from a whole corneal graft button unsuitable for keratoplasty.ResultsForty-four patients (45 eyes, mean follow-up of 27.6 ± 11.4 months) were enrolled. The partial thickness corneal grafts maintained clarity throughout follow-up with satisfactory cosmetic results. Mild conjunctival retraction occurred in 4 eyes (8.9 %) between 1 and 12 months after the surgery. Corneal graft melting occurred in 3 (6.7 %) eyes. Tube exposure and additional surgery to re-patch or suture the conjunctiva over the tube was needed in 1 (2.2 %) eye. None of the patients had graft infection or immunologic rejection.ConclusionsPartial thickness corneal grafts have favorable long-term outcome as a patch for GDD tubes with low rates of tube exposure and other complications.

Case series: Use of stromal lenticule as patch graft

“…As is known, the corneal patch graft provides good biocompatibility and strength, and compared with the scleral patch graft, it is thin and transparent, and thus cosmetically superior. 1 , 10 The stromal lenticule, significantly, is even thinner than the corneal patch graft (100 vs. 300 μm), and showed good strength in the present study. Moreover, the lenticule offers good accessibility: the corneal patch graft and the other patch grafts are difficult to obtain, which procedure is charged to the patient, whereas the lenticule is easily extracted by SMILE surgery and can be performed inexpensively.…”

Factors associated with conjunctival erosions after ahmed glaucoma valve implantation

“…In our study, there were three conjunctival erosions in the cornea graft group; this was an erosion rate of 10.34%, which was higher than that reported by Wigton et al (1.9%), Spierer et al (2.2%), and Ekici et al (1.8%). [ 24 26 27 28 ] We used split-thickness donor cornea allografts from the eye bank. Review of patient records indicate that two of the three conjunctival erosions occurred over an area that was not covered by the cornea allograft because the diameter of the graft was smaller than the length of the tube.…”

Baerveldt Scleral Patch Graft Abscess Secondary to Coagulase-Negative Staphylococcus

“…Regarding pericardial grafts in another study, the exposure rate was 16% with single-thickness processed pericardium in 31 eyes compared to 0% in 59 eyes covered with double-thickness processed pericardium ( p = 0.0002) [ 12 ]. A separate study looking at corneal patch grafts in 45 eyes noted a tube exposure frequency of 2.2% [ 13 ], while another looking at VisionGraft gamma-irradiated cornea had an exposure rate of 1.8% in 169 eyes [ 14 ]. The sample sizes of the latter studies were far smaller than that of the first study, which suggests a slight advantage for SPG in regards to tube exposure, but it is reasonable to believe that double-thickness processed pericardium and gamma-irradiated cornea may also reduce risk of exposure and possible subsequent infection.…”