Purpose: To determine whether topical treatment of mouse eyes with latanoprost alters intraocular pressure (IOP).
Methods: In a masked study design, NIH Swiss mice received a 2-microL topical instillation of 0.00015%, 0.0006%, 0.0025%, or 0.01% latanoprost or vehicle (phosphate-buffered saline [PBS]). After 1, 2, or 3 hours, the animals were anesthetized, and a fluid-filled glass microneedle connected to a pressure transducer was inserted through the cornea into the anterior chamber to measure IOP. The reduction of IOP after latanoprost measurement was calculated by the comparison between treated and nontreated eyes in the same mouse. The effect of latanoprost after a single 0.01% dose was also measured at 6, 12, and 24 hours. As in the previous study, the identity of all eye drop solutions was masked.
Results: In mouse eyes receiving topical PBS, the mean IOP was 14.8 +/- 2.2 mm Hg (n = 173 males). There was no significant difference in IOP between male and female eyes and between right and left eyes. At 1 hour after topical treatment with 0.00015% or 0.0025% latanoprost, IOP increased by as much as 11% +/- 7%. At 2 and at 3 hours after application, IOP decreased in a dose-dependent manner. These decreases were significant in eyes receiving 0.0025% or 0.01% latanoprost (P < 0.05, Student-Newman-Keuls test) and the largest decrease (14% +/- 8%) was noted 2 hours after treatment with 0.01% latanoprost. At 6, 12, or 24 hours after treatment, there was no difference in latanoprost- and PBS-treated eyes.
Conclusions: Latanoprost reduces mouse IOP in a dose-dependent manner. The mouse may be a useful model for studying the effect of drugs on IOP.