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Early conjunctival changes following treatment with metipranolol and preservatives are not reversible with
H Mietz1, U Schlötzer-Schrehardt, J H Lemke
1Department of Ophthalmology, University of Cologne, Germany. h.mietz@uni-koeln.de
Background:
Topical medication for the treatment of glaucoma alters the cellular and extracellular composition of the superficial and deep conjunctival layers. We sought to determine whether, after short-term use of metipranolol with preservatives, subsequent application of steroids or metipranolol without preservatives affects these conjunctival changes.
Methods:
Rabbits received topical metipranolol over a period of 6 months. For the following 2 months, one group received metipranolol without preservatives, and another group steroids. For controls, animals were treated with preservatives only or metipranolol with preservatives for 6 months. Superior bulbar conjunctiva was examined by light microscopy, immunohistochemistry, and transmission electron microscopy.
Results:
On light microscopic and immunohistochemical examination of conjunctival specimens from all groups, there was an increase of subepithelial collagen deposition in all treated groups. Treatment with steroids or preservative-free metipranolol did not alter the initial effects. By electron microscopy, additional extracellular matrix changes were seen as well as degenerative changes of tissue fibroblasts.
Conclusion:
The animal model used was able reliably to produce conjunctival changes following antiglaucomatous therapy. The changes seen were early changes, because there was no increase of inflammatory cells. Steroids did not significantly affect the changes. The beneficial effect of steroids used prior to glaucoma surgery remains controversial.