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Purpose: The current study aimed to investigate the time course of changes in choroidal circulation hemodynamics and their relationship to systemic circulation dynamics during the normal menstrual cycle in young, healthy women using laser speckle flowgraphy (LSFG). Methods: This prospective study included 26 eyes from 13 young, healthy women (21.3 ± 4.0 years) with a normal menstrual cycle and 24 eyes from 12 young, healthy men (21.8 ± 4.4 years) as a control group. The macular mean blur rate (MBR), a quantitative index of relative blood flow velocity in the choroid, was measured using LSFG. MBR, intraocular pressure (IOP), systolic blood pressure (SBP), diastolic blood pressure (DBP), mean blood pressure (MBP), and ocular perfusion pressure (OPP) were evaluated in the late follicular phase and mid-luteal phase in women and at baseline and 10 days after baseline in men, respectively. Results: In the female group, IOP, SBP, DBP, MBP, and OPP values were significantly higher in the mid-luteal phase than those observed in the late follicular phase (P = 0.035, P < 0.001, P = 0.041, P = 0.001, P = 0.014, respectively). The average macular MBR values in the late follicular phase and mid-luteal phase were 12.7 ± 5.3 and 13.7 ± 6.6 (+7.7 ± 19.4%), representing a significant increase in the mid-luteal phase (P = 0.041). The rate of change in MBR exhibited a significant positive correlation with changes in DBP and MBP (R = 0.456, P = 0.019 and R = 0.474, P = 0.014). However, there were no significant changes in any of the factors in the male group during the study period. Conclusions: Our results suggest that in young, healthy women with a normal menstrual cycle, choroidal blood flow velocity decreases during the late follicular phase and increases during the mid-luteal phase, depending on systemic circulatory dynamics. [ABSTRACT FROM AUTHOR]

Blood pressure (BP) and intraocular pressure (IOP) show seasonal variations. In this prospective study, we measured the IOP, BP, SCT and choroidal blood flow velocity of the right eye of 50 young, healthy volunteers (17 men and 33 women; mean age, 20.7 ± 4.5 years). In healthy participants, systolic BP (SBP), diastolic BP (DBP), MBP, OPP and MBR were significantly higher in winter than in summer. [Extracted from the article]

Purpose: Ripasudil, a Rho-associated coiled-coil-containing protein kinase (ROCK) inhibitor, is a novel drug for glaucoma in Japan. ROCK inhibition not only reduces intraocular pressure (IOP) but also increases ocular blood flow. We investigated the effects of ripasudil on optic disc blood flow (ODBF) in rabbit eyes and in isolated rabbit ciliary arteries. Methods: We measured IOP by tonometry and ODBF by laser speckle flowgraphy (LSFG) in male Dutch rabbits. A single drop (20 μL) of 0.8% ripasudil was delivered to the ocular surface after topical application of phenylephrine hydrochloride to reduce the ODBF. The effects of ripasudil on isolated rabbit ciliary artery smooth muscle contractions were measured in vitro with a myograph. Results: Ripasudil inhibited the reduction of ODBF induced by phenylephrine at 30 and 120 min after instillation ( P < .05). The blood flow change was not significantly correlated with the IOP change. Ripasudil induced a concentration-dependent relaxation in isolated rabbit ciliary arteries precontracted with a high-potassium solution. This relaxation was not mediated through the endothelium-dependent activities of nitric oxide synthase, prostacyclin, or the large-conductance calcium-activated K channel as shown by the inability of specific inhibitors of these pathways to block the ripasudil-induced relaxation. Conclusions: Taken together, our results showed that ripasudil not only decreased IOP but also increased ODBF in rabbits. However, the changes in IOP were not correlated with the changes in ODBF. Ripasudil also induced a concentration-dependent relaxation of isolated rabbit ciliary arteries through a NO-independent mechanism. Further investigation of the effect of ripasudil on ODBF is needed. [ABSTRACT FROM AUTHOR]

Purpose: In normotensive eyes, reduced ocular blood flow can lead to glaucoma pathogenesis. Drugs that reduce intraocular pressure (IOP) often cause vasodilation of the ciliary arteries and improve blood flow to the eye. A novel class of drugs called Rho-associated coiled coil-forming protein kinase (ROCK) inhibitors can lower IOP. Therefore, we tested the ability of two ROCK inhibitors, Y-27632 and Y39983, to relax rabbit ciliary arteries. Methods: We measured in vitro ciliary artery smooth muscle contractions by isometric tension recordings and changes of intracellular free calcium concentration ([Ca]) by fluorescence photometry. Results: Both Y-27632 and Y-39983 induced a concentration-dependent relaxation in rabbit ciliary arteries precontracted with a high-potassium (high-K) solution. The amplitude of relaxation induced by Y-27632 and Y-39983 was not affected by either 100 μM N-nitro- l-arginine methyl ester ( l-NAME) or 10 μM indomethacin. In Ca-free solution, Y-27632 and Y-39983 significantly inhibited the transient contraction of ciliary arteries induced by 10 μM histamine. However, neither Y-27632 nor Y-39983 affected the elevation of [Ca] induced by high-K solution and histamine. Conclusions: We concluded that Y-27632 and Y-39983 relaxed isolated rabbit ciliary artery segments in vitro. The mechanism of relaxation was not dependent on endothelial-derived factors such as nitric oxide (NO) or prostacyclin, nor was it dependent on changes in intracellular Ca concentration. [ABSTRACT FROM AUTHOR]

Abstract: We investigated the effects of prostaglandin F2α (PGF2α) analogues on the endothelin-1 (ET-1)-induced impairment of optic nerve head (ONH) blood flow and on ET-1-induced contraction in isolated ciliary artery segments. In male rabbits, one of four PGF2α analogues [0.0015% tafluprost, 0.0015% 15-hydroxyl tafluprost (15-OH tafluprost), 0.005% latanoprost, or 0.004% travoprost] was topically administered at various pretreatment times before intravitreal ET-1 injection. ONH blood flow was estimated by the laser speckle method, which expresses blood velocity as a quantitative index, the squared blur rate (SBR). SBR was measured just before (baseline value) and at 30, 60, and 120 min after ET-1 injection. SBR was significantly decreased from 4.47 ± 0.20 to 3.50 ± 0.10 (78.6 ± 2.4% of baseline) at 120 min after intravitreal ET-1 injection (5 pmol/eye). The ET-1-induced decrease was almost completely prevented by tafluprost and significantly inhibited by the other three analogues. The inhibitory effect lasted longest with tafluprost, as indicated by the effective pretreatment times (tafluprost: 90, 120, or 240 min; 15-OH tafluprost: 90, but not 120 or 240 min; latanoprost and travoprost: 120, but not 240 min). In vitro, the effects of PGF2α analogues on ET-1-induced contractions in male rabbit ciliary arteries were evaluated using an isometric tension recording system. Tafluprost, latanoprost, travoprost, and 15-OH tafluprost concentration-dependently relaxed the 10 nM ET-1-induced ciliary artery contraction. Improvement of the ocular circulation may be superior with tafluprost than with the other PGF2α analogues. The underlying mechanism may involve relaxation of ocular resistance vessels. [ABSTRACT FROM AUTHOR]