Histopathology, matrix metalloproteinase-2 and alpha smooth muscle actin expression in Tenon's capsule of eyes with congenital glaucoma

Purpose To evaluate the ultrastructural features of collagen fibrils, matrix metalloproteinase (MMP) and alpha-smooth muscle actin (alpha-SMA) expression in the Tenon's capsule of buphthalmic eyes. Methods A prospective comparative case series study was conducted on 35 buphthalmic eyes vs 25 control eyes. Children with congenital glaucoma (CG) who underwent a combined trabeculectomy-trabeculotomy procedure with mitomycin C (CTTM); the Tenon's capsule was obtained during the surgical procedure. The control group included children with strabismus, the Tenon's capsule was obtained in the course of strabismus surgery. Both H&E and Masson's trichrome staining were done. The Metalloprotenease-2 (MMP-2), alpha smooth muscle actin (alpha-SMA) immunohistochemical staining was performed. Results Mean collagen percentage area by Masson trichrome stain in Tenons capsule was significantly higher in buphthalmic eyes (54.76% +/- 0.32 vs 33.71% +/- 1.4; P < 0.001). The percentage area of alpha SMA expression in Tenons capsule was significantly higher in buphthalmic eyes (4.93% +/- 0.7 vs 2.00% +/- 0.5; P < 0.001). However, MMP2 expression in Tenons capsule of the buphthalmic group was significantly lower than that of the control group (12.88% +/- 2.95 vs 27.91% +/- 0.2 respectively) P = 0.02. Conclusions Tenon capsule of buphthalmic eyes have their own histopathological features and properties making them more liable for fibrosis with high rate of failure following antiglaucoma surgeries. Such detailed information has not been published before which may aid in the identification of new antifibrotic therapies in management of glaucoma.