Case Series: Keratolimbal Allograft as a Patch Graft for Glaucoma Drainage Devices

Donor Cornea Use in Scleral Surface Reconstruction

Objectives:

To investigate the indications for and results of treating scleral surface problems with donor corneal grafts that are not used in keratoplasty surgery or are left over from keratoplasty.

Materials and Methods:

The records of 16 patients in whom corneal tissue was used to repair a scleral tissue defect or cover an exposed glaucoma drainage implant were evaluated retrospectively. Partial-thickness grafts were prepared using a combined microkeratome system with artificial anterior chamber in 10 eyes and by manual dissection in 3 eyes. Full-thickness grafts were used in 3 eyes.

Results:

There were 8 female and 8 male patients aged 5-79 years (mean: 39.37±24.68). Indications for the use of corneal tissue on the scleral surface were limbal dermoid excision (n=2), pterygium surgery (n=1), intraocular lens removal and scleral fixation intraocular lens (SFIOL) implantation (n=1), exposed SFIOL suture coverage (n=1), trauma (n=2), scleral tissue loss due to repeated glaucoma surgeries (n=5), and exposed glaucoma drainage implant (n=4). The patients were followed for 6-42 months (mean: 14.37±9.14). None of the patients had graft infection, thinning, immunological graft rejection, or vision loss during follow-up. Tectonic lamellar grafts did not adversely affect final visual acuity in any case. At final examination, a good combination of graft and recipient tissue, a smooth ocular surface, and a cosmetic appearance were achieved in all eyes.

Conclusion:

Donor corneas that are not suitable for corneal transplantation or left over from the cornea transplant can be used in patients with scleral tissue loss due to various pathologies and in the treatment of glaucoma drainage implant erosion. In these cases, the use of corneal grafts provides a good ocular surface restoration and cosmetic appearance. The effectiveness and safety of this method should be investigated with large patient series and long follow-up times.

Surgical and Immunohistochemical Outcomes of Scleral Reconstruction with Autogenic, Allogenic and Xenogenic Grafts: An Experimental Rabbit Model

Purpose: Choukroun's platelet-rich fibrin (PRF), a second-generation platelet concentrate, has unique morphological and chemical features and may be considered as a scaffold for scleral reinforcement and regeneration. The purpose of this study was to compare the use of xenogenic human-derived amniotic membrane (HAM), allogenic sclera, and autogenic PRF in rabbit lamellar scleral defect model with respect to both anatomical and immunohistochemical improvement. Methods: A total of 45 adult New Zealand rabbits were randomized into five groups: normal control; without surgical procedure, negative control; scleral defect model (SDM), xenogenic HAM; SDM+HAM graft, allogenic sclera; SDM+allogenic sclera graft, autogenic PRF; SDM+autogenic PRF graft. Clinical findings, Hematoxylin&Eozin (HE), Masson Trichrome, Verhoeff Acid Fuchsin, Transforming Growth Factor β Receptor 1, Fibroblast Growth Factor, Bone Morphogenetic Protein 2, collagen type 1, aggrecan, and Matrix Metalloproteinase 2 were evaluated. Results: Ocular surface inflammation was significantly lower in normal control and autogenic PRF groups (p < .001). Graft was avascular and not integrated to scleral wound area in 25% rabbits of allogenic sclera group (p = .02), was out of the scleral wound in 33.3% rabbits of xenogenic HAM group (p > .05), all the grafts were at the normal location and viable in autogenic PRF group. The inflammation and vascularization in autogenic PRF group was significantly lower than negative control and xenogenic HAM groups in HE (p < .001). The collagen score of negative control and xenogenic HAM groups were significantly lower than normal control (p < .001) and autogenic PRF (p < .001) groups. There were insignificant differences between allogenic sclera and autogenic PRF groups (p > .05). For immunohistochemistry, the closest values to normal control group were detected in autogenic PRF group for all immunomarkers. Conclusion: Autogenic PRF showed superior features via its excellent anatomical and chemical composition for scleral regeneration when compared to single-layered xenogenic HAM and allogenic sclera grafts.