When a glaucoma filtering operation fails, the causes may be categorized as intraocular, scleral, or extraocular. Some authors have implicated that extracocular causes of failure are due to closure of the external opening by connective tissue.
This histologic investigation was undertaken to examine the surgical wounds of 8 experimental subjects including 4 albino and 4 pigmented rabbits. Under general anesthesia by pentothal sodium, a single punch sclerectomy was performed on each right eye. A trabeculectomy was performed on the left eye. Seven and ten days following surgery, globes were removed and immediately fixed in Karnovsky´s fixation solution. Following fixation, globes were bisected through the surgical wounds, and one-half was studied using standard light microscopy. The other one-half specimens were blocked and processed for transmission electron microscopy.
The results of the evaluations were as follows:
1. Full thickness sclerectomy wounds healed by ingrowth of fibroblasts from subconjunctival and episcleral tissue, but trabeculectomy wounds showed no communication with extrascleral tissue.
2. Quantitatively, proliferaotin of fibroblasts were more exuberant in the sclerectomied ,eyes compared to trabeculectomies.
3. There was no evidence of significant difference between albino and pigmented rabbits.
4. The granulation tissue composed mainly of fibroblasts resembles smooth muscle cell (myofibroblasts) and extracellular collagen constitutents.
Ultrastructurally, these cells showed massive bundles of intracytoplasmic microfilaments with scattered dense bodies, wrinkled and folded nuclei indicative cellular contraction, and abundant cisternae of rough endoplasmic reticulum informative activity of cellular proliferation.
From those results, author conclude that smooth muscle antagonists may inhibit the proliferation of myofibroblasts after glaucoma filtering operations.
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