Graft Ulcer Research Articles

Skin graft survival after external beam irradiation.

Difficulties with skin graft ulceration after radiation therapy for cancer have led many to question the suitability of this method of soft-tissue coverage and its cost-effectiveness. The objective of this study was, therefore, to assess skin-graft integrity subjected to postoperative external beam irradiation in a rat model. The model consisted of a rectangular full-thickness skin graft raised and reapplied to its original bed on the dorsum of each rat. Five groups of adult male Sprague-Dawley rats (n = 8 per group) were established. Group A was the control group and was not given postoperative irradiation. Groups B, C, D, and E received postoperative unfractionated cobalt60 irradiation 4 weeks after grafting for a total dose of 15, 20, 25, or 30 Gy, respectively. Weekly skin-graft evaluation was performed for the 4 weeks after irradiation (8 weeks after surgery) by measuring areas of graft loss using computerized planimetry. After the animals were killed, histologic samples were obtained from normal unirradiated skin and from both intact and ulcerated skin-graft sites. Graft loss after irradiation of < or = 20 Gy was similar to that of the unirradiated controls. Occurring as early as 1 week after treatment, a two-fold increase in graft ulceration was observed with doses of > or = 25 Gy (p = 0.0007). Only partial healing of ulcerations was noted by the fourth week after treatment. Histologic changes associated with the irradiation of skin grafts using doses of 25 Gy or higher included hyaline degeneration, fibrinoid necrosis, telangiectasia, and edema. Granulation tissue predominated as a mechanism of healing in areas of graft ulceration. The intensity of inflammatory cell infiltrate did not correlate with radiation dose. The authors concluded that postoperative, unfractionated irradiation can induce skin-graft loss at doses of 25 Gy or higher. Fractionated irradiation or longer intervals between grafting and irradiation may increase skin-graft tolerance; however, further studies are warranted.

Clinical and Histopathologic Changes in the Host Cornea After Epikeratoplasty for Keratoconus

Five consecutive patients underwent epikeratoplasty for keratoconus. Postoperatively, four patients had poor visual acuity (average, 20/200) secondary to folds in Descemet's membrane and interface scarring. Two underwent penetrating keratoplasty eight months later. Histopathologic examination of the host corneas and the overlying lenticules disclosed epithelial irregularity and subepithelial fibrosis. The host corneas showed folds in Descemet's membrane and focal posterior stromal fibrosis. Electron microscopy disclosed breaks in Bowman's membrane with irregular collagen, posterior aggregates of amorphous material, and focal endothelial degeneration. The fifth patient had graft ulceration and vascularization that required removal of the lenticule. She underwent a penetrating keratoplasty five months later and histopathologic examination demonstrated persistent folds in Descemet's membrane. Immunostaining of specimens from three cases disclosed a reduced expression of sulfated epitopes of keratan sulfate and an increase in sulfated dermatan sulfate in the lenticule and host corneal tissues. These alterations in stromal proteoglycans are characteristic of stromal scars and keratoconus and provide evidence of pathologic processes in the graft tissue. Because of potential complications, epikeratoplasty should be considered only for those patients who are unsuitable candidates for contact lenses or penetrating keratoplasty.

Extended-Wear Contact Lenses in Patients with Corneal Grafts and Aphakia

Extended-wear contact lenses (EWCL) were fitted successfully on 61 aphakic eyes with penetrating corneal grafts. In two- to 32-months follow-up there were 26 eyes that had varying amounts of superficial neovascularization of the grafts and one Staphylococcus epidermidis corneal graft ulcer. There were five homograft rejections, all occurring in severely diseased eyes. Variable vision and visual acuity less than that with hard contact lenses or aphakic spectacles were the most frequent problems. Both were due to the high corneal astigmatism present in many patients. The results indicate that EWCLs may be used safely by patients with penetrating corneal grafts and aphakia, particularly if there is no host corneal edema, scarring, or vascularization, if there are no synechias to the graft wound, and if the astigmatism is less than 3.0 diopters.