Effect of 0,5% timolol maleate on the ciliary epithelium of the dog
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1996-02-15
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Moraes Silva, M. R.B. [UNESP]
Macedo, A. R. [UNESP]
Gregório, E. A. [UNESP]
Schellini, S. A. [UNESP]
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Purpose: The ocular hipotensive action of β-blockers is done by aqueous humor production decrease. Therefore, the intimate mechanism of this action remains unknown. We performed this work in order to study ciliary epithelium ultrastructural possible alterations caused by timolol maleate (TM). Methods: The ciliary epithelium was studied in 32 dogs divided in 4 groups: G1 - 8 dogs with normal IOP and treated under 100μl 0,5% TM on the right eye (RE); G2 - 8 dogs with intraocular hypertension (caused by 200ml/kg H2O dosage injection into peritoneum) and under the same treatment as G1 ; G3 - 8 dogs with normal IOP and treated under 100μl 0,5% TM, 12/12 hours during 1 week on RE; G4 - 8 dogs with ocular hypertension (same method as G21 and same treatment as G3. Results: In G1 similar alterations were observed in BE enlargement of intercellular spaces from both epithelium and in lesser degree between the two epithelia; mitochondrial edema in both epithelia, RCR dilation on non-pigmented epithelium. The enlargement between epithelia was larger on the treated eve in G2 the same G1 alterations were observed, therefore, there was mitochondrial edema in a larger number of non-pigmented cells. In G3 the alterations were similar to G1 therefore, there was a larger RCR dilation observed in a larger number of cells mitochondrial rupture, irregular and intense vacuolation of cytoplasm on the treated eye. In G4 alterations were also similar, but RE showed vacuoles compressing the nucleus of the cells. Conclusion: The observed alterations were similar in all the groups and in BE varying only in degree and being larger in G3 and G4. Therefore, as TM could have been absorbed systematically, alterations could be assigned to it.
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Investigative Ophthalmology and Visual Science, v. 37, n. 3, 1996.