Korean J Ophthalmol.  2012 Aug;26(4):265-270. 10.3341/kjo.2012.26.4.265.

Comparative Study of Encapsulated Blebs Following Ahmed Glaucoma Valve Implantation and Trabeculectomy with Mitomycin-C

• Bae K
• Suh W
• Kee C

• KMID: 1387393
• DOI: http://doi.org/10.3341/kjo.2012.26.4.265

Abstract

PURPOSE
To compare the histopathologic and morphologic findings of encapsulated blebs following Ahmed glaucoma valve implantation and primary standard trabeculectomy with mitomycin-C.
METHODS
We reviewed the records of patients with otherwise uncontrollable glaucoma who had undergone Ahmed glaucoma valve implantation or trabeculectomy with mitomycin-C. Five eyes that underwent Ahmed valve implantation and three eyes that underwent trabeculectomy needed surgical revision of the initial surgery due to encapsulated bleb development with total loss of function. The surgically removed encapsulated blebs were analyzed macroscopically and microscopically.
RESULTS
Removal of the encapsulated bleb was performed at a mean follow-up time of 26.6 +/- 19.4 weeks in the Ahmed valve implantation group and 12.0 +/- 11.4 weeks in the trabeculectomy group. The fibrotic wall of the encapsulated blebs had an overall thickness of 2.48 +/- 0.42 mm in the Ahmed valve implantation group and 1.62 +/- 0.37 mm in the trabeculectomy group. Macroscopically, the coconut flesh-like smooth surface was split into two layers, and the wall of the capsule was thicker in the Ahmed valve implantation group than in the trabeculectomy group. Histopathologically, the fibrotic capsule was composed of an inner fibrodegenerative layer and an outer fibrovascular layer, and there were no histopathological differences between the two groups.
CONCLUSIONS
The fibrotic capsule wall was thicker in the Ahmed valve group, but there were no differences in histological findings between the two groups.

Keyword

Antimetabolites; Fibrosis; Glaucoma drainage implants; Trabeculectomy

MeSH Terms

Adult
Blister/*surgery
Female
Glaucoma/physiopathology/*surgery
*Glaucoma Drainage Implants
Humans
Infant
Male
Middle Aged
Mitomycin/*therapeutic use
Nucleic Acid Synthesis Inhibitors/*therapeutic use
Reoperation
*Trabeculectomy
Treatment Outcome

Figure

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  Fig. 1 Gross photographs of excised EB following trabeculectomy (A, outer surface; B, inner surface), and Ahmed valve implantation (C, outer surface; D, inner surface).

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  Fig. 2 Magnified photomicrograph of the encapsulated bleb following Ahmed valve implantation stained with H&E (×400). The vascular structure of the outer layer resembled normal collagenous connective tissue, and the inner surface consisted of dense collagen fibers with elastoid degeneration (arrow).

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  Fig. 3 Magnified photomicrograph of the encapsulated bleb following Ahmed valve implantation stained with Masson's trichrome (×400). Note collagen fiber staining in the outer fibrovascular portion of the bleb and fibrobastic proliferation.

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  Fig. 4 Photomicrograph of the encapsulated bleb following trabeculectomy stained with Alcian blue (×100). Increased ground substance staining is present, especially around the cells (arrow).

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  Fig. 5 Photomicrographs of the encapsulated bleb following trabeculectomy (A), and Ahmed valve implantation (B) showing fibrodegenerative changes in the inner layer (black arrowhead) and outer fibrovascular layer (white arrowhead) (H&E, ×100). The ratio of outer fibrovascular layer thickness to inner fibrodegenerative layer thickness was approximately 3 : 1 in both groups.

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