Histopathologic Findings in Early Encapsulated Blebs of Young Patients Treated With the Ahmed Glaucoma Valve

Thieme, Hagen; Choritz, Lars; Hofmann-Rummelt, Carmen; Schloetzer-Schrehardt, Ursula; Kottler, Ulrike B.

doi:10.1097/ijg.0b013e3181e080ef

Cited by 53 publications

(43 citation statements)

References 12 publications

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“…In the control group, the inner layer of the fibrous capsule was compact collagen fibers characterized by transdifferentiation of fibroblasts into myofibroblasts, and the outer layer of the fibrous capsule was vascularized. These results were consistent with those of Thieme et al [3], who reported histopathological findings of encapsulated blebs around AGVs.…”

Section: Discussionsupporting

confidence: 83%

“…Another experimental study reported that the thinner and more vascular capsule formed by a modified AGV with expanded polytetrafluoroethylene may result in decreased resistance to aqueous egress compared with avascular fibrous encapsulation [29]. Therefore, in the study group, the dilated blood vessels located throughout a thin and loose fibrous capsule might be more effective for fluid transport through the capsular wall than in the control group [3,29,30]. …”

Section: Discussionmentioning

confidence: 99%

“…A previous histopathological study reported that little vasculature may further impair the transportation of fluid out of the cyst or through the cyst wall in the encapsulated bleb formed after AGV implantation [3]. Another experimental study reported that the thinner and more vascular capsule formed by a modified AGV with expanded polytetrafluoroethylene may result in decreased resistance to aqueous egress compared with avascular fibrous encapsulation [29].…”

Section: Discussionmentioning

confidence: 99%

“…However, glaucoma implants including AGVs stimulate a foreign body fibrotic response that encapsulates the glaucoma implant body and increases aqueous outflow resistance through the capsule. This can lead to elevated intraocular pressure (IOP) requiring further surgical intervention [2,3]. …”

Section: Introductionmentioning

confidence: 99%

“…Histopathologically, the inner layer of the encapsulated bleb facing the AGV surface consists of compressed collagen fibers characterized by a pronounced transformation of fibroblasts into myofibroblasts [3]. The transdifferentiation of fibroblasts into myofibroblasts is a crucial step in wound healing and scar formation [4] and is characterized by the de novo synthesis of α-smooth muscle actin (α-SMA) and the incorporation of α-SMA into actin stress fibers as part of the contractile apparatus [5].…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Tissue Response to Implanted Ahmed Glaucoma Valve with Adjunctive Amniotic Membrane in Rabbit Eyes

Lee¹,

Park²,

Kim³

et al. 2014

Ophthalmic Res

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Aims: To investigate the histopathology of the fibrous capsule around Ahmed glaucoma valves (AGVs) implanted with adjunctive amniotic membranes in rabbits. Methods: AGV implantation with or without adjunctive amniotic membrane was performed in a single eye of 20 albino rabbits. The upper surface of the AGV body was covered with amniotic membrane in the study group. After 2 months, histology was used to compare the thickness and characteristics of the fibrous capsule, transdifferentiation of myofibroblasts, and density of blood vessels and leukocytes between the study and control groups. Results: The fibrous capsule along the roof of the bleb was composed of compact collagen fibers with minimal vascularization in the control group. In contrast, in the study group, the fibrous capsule was looser and had a more disorganized collagen architecture. The thickness of the fibrous capsule and the myofibroblast layer was significantly thinner in the study group than in the control group (p < 0.001). The number of CD31-positive blood vessels did not differ between the two groups (p = 0.235). CD45-positive inflammatory cells were more frequently observed in the study group than the control group (p = 0.001). The groups did not differ in the thickness of the fibrous capsule or myofibroblast layer, or the density of blood vessels and leukocytes along the floor of the bleb. Conclusions: Adjunctive amniotic membranes could reduce the risk of encapsulation and aqueous outflow resistance by altering the tissue response to implanted AGVs and subsequent formation of a loose thin capsule.

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Section: Discussionsupporting

confidence: 83%