Experimental and clinical outcomes of filtering bleb plasty using allografts

PURPOSE. To refine the technique of filtering bleb (FB) plasty using allografts in an experimental model on laboratory animals, evaluate the histomorphological outcomes, and assess the efficacy and safety of plastic reconstruction of cystic FBs in the clinical setting.
METHODS. Steroid-induced glaucoma was modeled in 30 rabbits (30 eyes), followed by an anti-glaucoma procedure with allogeneic sponge drainage. Ninety days post-operatively, a conjunctival defect was created in the FB area and covered with an allogeneic biomaterial derived from fascial sheaths for conjunctival reconstruction.
In cases of cystic FBs, revision was performed with dissection of sclero-conjunctival adhesions. The allograft was placed over the scleral flap in the filtration area, shaped, and secured to the surrounding sclera. The Tenon’s capsule and conjunctiva were then positioned over the biomaterial and anchored to the limbus.
RESULTS. A moderately diffuse FB was observed in the early postoperative period following conjunctivoplasty. The allogeneic biomaterial was visualized under the conjunctiva in the filtration area, adjacent to the eye globe. Over time, a connective tissue regenerate, structurally similar to the underlying bed, formed at the site of the allograft. Histomorphological studies confirmed that the stages of allograft replacement with newly formed tissue were a natural result of the transplantation process.
In FB revisions, sclero-conjunctival adhesions were dissected, and the allograft for conjunctival reconstruction was placed over the scleral flap, shaped, and secured with 8/0 interrupted sutures. Ultrasound biomicroscopy was performed to examine the topography of ocular surface structures in the long-term follow-up period after conjunctival reconstruction.
CONCLUSION. The developed technique for conjunctivoplasty in cystic FBs using allografts is a safe and reliable method for reinforcing ocular surface tissues involved in FB formation. This approach provides therapeutic, functional, and cosmetic benefits.

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