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Daytime profile of the intraocular pressure and tear production in normal dog |
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| Authors: | Claudia Giannetto,Giuseppe Piccione, Elisabetta Giudice&dagger |
| Affiliation: | Department of Experimental Sciences and Applied Biotechnology, Laboratory of Veterinary Chronophysiology, Faculty of Veterinary Medicine, University of Messina, Polo Universitario dell'Annunziata, 98168 Messina, Italy;;Department of Veterinary Public Health, University of Messina, Polo Universitario dell'Annunziata, 98168 Messina, Italy |
| Abstract: | Objective To evaluate the circadian rhythms of intraocular pressure (IOP) and tear production in dog exposed to a natural photoperiod. Animals studied We used 12 clinically healthy Beagles dog housed under natural photoperiod at indoor temperature and humidity. Procedure Intraocular pressure and Schirmer tear test (STT) I were measured every 4 h over a 48-h period in both eyes in each animal. Statistical analysis of the data was performed by one-way repeated-measures anova , Student's t -test, and single cosinor method. Results On each day, there was a highly significant effect of time on both parameters. A statistically significant difference of STT I values was observed comparing left and right eyes ( P < 0.0001). Robust daily rhythms were observed for both parameters, IOP values showed diurnal acrophase (left eye: 09:33 ± 00:50 h; right eye: 09:25 ± 00:22 h), while STT I values showed nocturnal acrophase (left eye: 20:27 ± 00:46 h; right eye: 20:00 ± 00:05 h). Conclusion This study has demonstrated circadian rhythms in both IOP and STT I. |
| Keywords: | circadian rhythm dog eye intraocular pressure natural photoperiod Schirmer tear test |