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OBJECTIVE To determine the effect of topical ophthalmic administration of 0.005% latanoprost solution on aqueous humor flow rate (AHFR) and intraocular pressure (IOP) in ophthalmologically normal dogs. ANIMALS 12 adult Beagles. PROCEDURES In a masked crossover design involving two 10-day experimental periods separated by a 7-day washout period, dogs were randomly assigned to first receive latanoprost or artificial tears (control) solution and then the opposite treatment in the later experimental period. Each experimental period was divided into a baseline phase (days 1 to 3), baseline fluorophotometry assessment (day 4), treatment phase (1 drop of latanoprost or artificial tears solution administered twice daily in each eye on days 5 to 9 and once on day 10), and posttreatment fluorophotometry assessment (day 10). Measured fluorescein concentrations were used to calculate baseline and posttreatment AHFRs. The IOP was measured 5 times/d in each eye during baseline and treatment (days 5 to 9) phases. RESULTS Mean baseline and posttreatment AHFR values did not differ significantly in either experimental period (latanoprost or control). In the latanoprost period, mean IOP was significantly lower during treatment than at baseline; there was no difference in corresponding IOP values during the control period. In the latanoprost period, mean IOP was significantly higher on the first day of treatment than on subsequent treatment days. CONCLUSIONS AND CLINICAL RELEVANCE In ophthalmologically normal dogs, topical ophthalmic administration of 0.005% latanoprost solution significantly decreased IOP but did not affect AHFR. Thus, the ocular hypotensive effect of latanoprost did not appear to have been caused by a reduction in aqueous humor production. [ABSTRACT FROM AUTHOR]

Objective--To evaluate aqueous humor flow rate in the eyes of clinically normal cats by use of a noninvasive technique successfully used in other species. Animals--20 domestic shorthair cats. Procedures--1 drop of 10% fluorescein sodium was instilled into both eyes of 5 cats every 5 minutes until 3 drops had been administered. Fluorophotometry was performed at 2, 4, 5, 6, 7, 8, 9, and 10 hours after fluorescein application to monitor fluorescein removal and determine aqueous humor flow rate. The 3-drop protocol was used for the remaining 15 cats, and fluorophotometry was performed at 5, 6, 7, and 8 hours after fluorescein application. Aqueous humor flow rates were calculated manually by use of established equations with minor adjustments to constant values to reflect feline anatomic features. Correlation coefficients and slope ratios were calculated to assess the legitimacy of the flow rate data. Paired t tests were calculated to assess for differences between the right and left eyes. Results--Mean ± SD calculated aqueous humor flow rate in the right, left, and both eyes of the 20 cats was 5.94 ± 2.30 µL/min, 5.05 ± 2.06 µL/min, and 5.51 ± 2.21 µL/min, respectively. Correlation coefficients and slope ratios revealed that the aqueous humor flow rates were accurate. No significant differences in values for the right and left eyes were detected. Conclusions and Clinical Relevance--Accurate aqueous humor flow values for cats can be determined by use of the fluorophotometric technique evaluated in this study. [ABSTRACT FROM AUTHOR]