The Effects of Topical Travoprost or Unoprostone on Retinal Vessel in Dutch Rabbits.

Abstract

Abstract: : Purpose: To evaluate whether topically instilled travoprost (0.004%) or unoprostone (0.12%) reaches to the ipsilateral posterior retina at pharmacological levels and acts on retinal arteries in normal Dutch rabbits. Methods: A 30µl of travoprost (0.004%) or unoprostone (0.12%) was unilaterally instilled once or once (travoprost) daily or twice (Unoprostone) daily for 7 days in Dutch rabbits and effects on the intravitreously injected 0.5ng endothelin(ET)–1–induced of retinal arteries were constriction was evaluated. Retinal arteries diameters were photographed 15 min after a single or the last instillation when ET–1 was injected thereafter and 15,30 and 60 min in both eyes. Similar experiments were carried out in other groups of rabbits instilled with travoprost once daily for 7 days to study the effect of indomethacin (5 mg/kg) pretreatment. Retinal arteries’ diameters were normalized to those of the optic disks. All measurements were performed by masked investigators. Results: Only in rabbits instilled with travoprost once daily for 7 days, 0.5ng ET–1 induced–constriction was significantly less by about 50% in the treated– than in the vehicle–treated side at all time points (P=0.03~0.04, n=8), which was abolished indomethacin pretreatment (P>0.5, n=8). The IOP, pulse rate and blood pressure showed no significant change in all experiments. Conclusions: Topically instilled 0.004% travoprost reaches the ipsilateral posterior retina in normal rabbits at pharmacological levels and partly inhibits the ET–1 induced constriction of retinal arteries. This effect was independent of the IOP change and probably associated with production of endogenous prostaglandins.

Keywords: blood supply • intraocular pressure • neuroprotection