LAUSR

OBJECTIVE This study was designed to evaluate the changes in intraocular pressure (IOP), pupil diameter (PD), and anterior segment parameters using ultrasound biomicroscopy (UBM) after instillation of preservative-free (PF) tafluprost in normal dogs. PROCEDURES Six beagle dogs were used. PF tafluprost was instilled in one randomly selected eye, and PF artificial tear was instilled in the other eye (control). IOP and PD were measured every 15 min for the first hour, every 2 h for the next 17 h, and at 24 h and 36 h postinstillation (PI). Anterior segment parameters including geometric iridocorneal angle (ICA), width of the entry of the ciliary cleft (CCW), length of the ciliary cleft, area of the ciliary cleft, and depth of the anterior chamber were measured with UBM before and after PF tafluprost instillation. RESULTS Compared with the control group, IOP was significantly lower from 4 h PI to 24 h PI and PD was significantly smaller from 30 min PI to 18 h PI (P < 0.05). Among UBM parameters, ICA and CCW significantly decreased and increased after PF tafluprost instillation, respectively (P < 0.05). Other parameters showed no significant changes. CONCLUSIONS Instillation of PF tafluprost lowered IOP and induced miosis in normal canine eyes. Alterations in ICA and CCW occurred simultaneously, which probably affected the outflow of aqueous humor. PF tafluprost could be considered an alternative prostaglandin analog in the treatment of canine glaucoma.