The Dry Eye Zone

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Abstract: More on cyclosporine, in acute cases

Interesting findings. Very severe patients with unhelpful experiences of Restasis might relate to the bunnies....

Invest Ophthalmol Vis Sci. 2009 Feb 14. [Epub ahead of print]Links
Neurological evaluation of acute lacrimomimetic effect of Cyclosporine in an experimental rabbit dry eye model.
Toshida H, Nguyen D, Beuerman RW, Murakami A.
Ophthalmology, Juntendo University School of Medicine, Tokyo, Japan.

PURPOSE: To evaluate acute lacrimation cased by Cyslosporine A (CsA) eye drops neurologically in rabbit.

METHODS: Normal and parasympathectomized adult male New Zealand white rabbits received a single instillation of 0.1% CsA or vehicle eye drops. Schirmer's tear test (STT), the flow rate of lacrimal gland (LG) fluid from the excretory lacrimal duct of the main LG, and the blink rate (over a 3-min period) were measured before and after instillation of CsA or vehicle. Light microscopy was performed to examine the main LG. in vitro Protein release from LG fragments was assessed after incubation with CsA for 30 minutes.

RESULTS: In normal rabbits, both the STT value and the flow rate of LG fluid were significantly increased after treatment with CsA compared with vehicle (p<0.05). In contrast, no changes were found in denervated eyes. The blink rate of CsA-treated eyes was significantly higher than that of vehicle-treated in normal rabbits (p<0.005), while that of denervated eyes decreased significantly after CsA instillation compared with before administration (p<0.005). Light microscopy showed that the cytoplasm of acinar cells was packed with secretory granules in denervated LG tissue at 7 days after parasympathectomy. The same finding was observed at 3 hours after CsA instillation. CsA had no stimulatory effect on protein release by acinar cells in LG fragments at all concentrations tested.

CONCLUSION: These results suggest that CsA has no direct effect on tear fluid secretion from the LG in a very acute model. Instead, CsA increases a reflex tear flow.
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