Abstract
Purpose: :
To evaluate conjunctival changes after chronic, twice a day dosing of Dorzolamide hydrochloride/Timolol maleate and Brimonidine tartrate/Timolol maleate alone or with addition of Cyclosporine 0.05%.
Methods: :
Twelve New Zealand white rabbits were randomized into groups of four and received twice daily topical application of Dorzolamide hydrochloride/Timolol maleate (DT) or Brimonidine tartrate/Timolol maleate (BT) alone in one eye and with addition of Cyclosporine 0.05% in the other eye for 80 days. The control group received Cyclosporine 0.05% in one eye and preservative-free artificial tears (PFAT) in the other. Conjunctival specimens were evaluated by light microscopy after hematoxylin and eosin staining. Goblet cells and lymphocytes were counted in the epithelium and superficial stroma by 3 masked observers and compared among groups.
Results: :
The number of lymphocytes in the conjunctival epithelium and stroma was significantly lower in eyes treated with BT or PFAT than eyes treated with DT alone (p< 0.001).The number of conjunctival lymphocytes was similar among conjunctival specimens exposed to DT with Cyclosporine 0.05%, BT, Cyclosporine 0.05%, or PFAT (p>0.05). The number of the goblet cells was significantly higher in the DT with Cyclosporine 0.05% group compared to DT alone. The number of goblet cells was similar between the eyes treated with BT, BT with Cyclosporine 0.05%, Cyclosporine 0.05% alone and PFAT.
Conclusions: :
Twice daily dosing of DT produced significantly more inflammation than BT or PFAT. Cyclosporine 0.05% seemed to suppress this inflammatory response. The number of the goblet cells increased when DT was used with Cyclosporine 0.05%. Human studies are needed to better understand the clinical effects of Cyclosporine 0.05% on the ocular surface exposed to glaucoma medications.
Keywords: ocular irritancy/toxicity testing • pathology: experimental • conjunctiva