Effects of Repeated Administrations of Tafluprost, Latanoprost, and Travoprost on Optic Nerve Head Blood Flow in Conscious Normal Rabbits

Purpose : The aim of this study was to evaluate and compare the effects of repeated administrations of three prostaglandin F-2 alpha analogs (tafluprost, latanoprost, and travoprost) on optic nerve head (ONH) blood flow in normal rabbits. Methods : Male Dutch rabbits were housed under a 12-h light-dark cycle for use in this study. A quantitative index of blood flow, the squared blur rate (SBR), was determined using laser speckle flowgraphy. Saline, 0.0015% tafluprost, 0.005% latanoprost, or 0.004% travoprost (each 50 mu L) was topically administered into the left eye once daily for 28 days. ONH blood flow was measured before the start at the course of treatment (baseline), and on day 14 and/or day 28 [measurements being made at 0, 30, and/or 60 min after drugs application on day 14 and/or day 28]. Heart rate was also measured at these time points. Results : Tafluprost, latanoprost, and travoprost each increased the ONH blood flow at all measurement points on day 14 and/or day 28. The 0 min SBR value on day 14 was greater than the baseline SBR value by 8.7% +/- 4.4% for tafluprost and by 5.8% +/- 1.7% for latanoprost. The 0 min SBR value on day 28 was greater than the baseline SBR value by 11.9% +/- 3.9% for tafluprost, by 7.2% +/- 4.3% for latanoprost, and by 6.7% +/- 3.5% for travoprost. The increasing state of the ONH blood flow continued within 60 min after a topical administration of tafluprost, latanoprost, or travoprost. Tafluprost, latanoprost, and travoprost did not change heart rate (vs. the baseline value) at any measurement points. Conclusions : Repeated topical administration of any of the three prostaglandin F-2 alpha analogs increased ONH blood flow in rabbits, without changing heart rate. The increase in ONH blood flow induced by tafluprost was greater than that induced by latanoprost (P = 0.086) or travoprost (P = 0.037) at 60 min on day 28.