Effects of pranidipine, a new calcium antagonist, on circulation in the choroid, retina and optic nerve head

Tamaki, Yasuhiro; Araie, Makoto; Tomita, Ken; Urashima, Hiroki

doi:10.1076/ceyr.19.3.241.5318

Cited by 12 publications

(6 citation statements)

References 18 publications

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“…In the middle panel, the frequency spectrum of the spontaneous oscillations after ET-1 shows several bands corresponding to superimposed frequencies ranging from 0.01 to 0.09 Hz. In the lower panel, Fourier analysis after amlodipine shows a minor band at 0.01 Hz, so there was a marked decrease in the frequency of the oscillations agreement with several previous experimental (isolated vessel) and clinical studies showing that dihydropyridines can cause vasodilation and increase blood flow within the ocular circulation [5,23,24], although there is some controversy regarding clinical effects [25][26][27].…”

Section: Discussionsupporting

confidence: 74%

Amlodipine effects on vasomotion in rabbit external ophthalmic artery

Delgado¹,

Marques-Neves²,

Rocha³

et al. 2009

Graefes Arch Clin Exp Ophthalmol

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Our study has two main conclusions: (1) amlodipine, an L-type calcium channel blocker, caused intense vasodilation and decreased both frequency and amplitude of the spontaneous oscillations observed in the rabbit external ophthalmic artery and its collaterals, and (2) when we applied amlodipine in arteries previously contracted by the administration of ET-1, vascular resistance greatly decreased and spontaneous oscillations were abolished. Since ET-1 levels are increased in several ischemic ocular diseases, amlodipine might be beneficial in these patients, allowing a protective action against vasospasm.

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Section: Discussionsupporting

confidence: 74%

Amlodipine effects on vasomotion in rabbit external ophthalmic artery

Delgado¹,

Marques-Neves²,

Rocha³

et al. 2009

Graefes Arch Clin Exp Ophthalmol

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“…1998). In addition, retinal circulation can be measured in animals if a blue‐component argon laser is substituted for the diode laser (Tamaki et al. 1994, 1996b, 1999a, 2003).…”

Section: Specific Parametersmentioning

confidence: 99%

Use of laser speckle flowgraphy in ocular blood flow research

Sugiyama

Araie

Riva

et al. 2009

Acta Ophthalmologica

Self Cite

344

314

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ABSTRACT.Laser speckle flowgraphy (LSFG) allows for the quantitative estimation of blood flow in the optic nerve head, choroid, retina and iris in vivo. It was developed to facilitate the non-contact analysis of ocular blood flow in living eyes, utilizing the laser speckle phenomenon. The technique uses a fundus camera, a diode laser, an image sensor, an infrared charge-coupled device (CCD) camera and a high-resolution digital CCD camera. Normalized blur (NB), an approximate reciprocal of speckle contrast, represents an index of blood velocity, and shows a good correlation with tissue blood flow rates determined with the microsphere method in the retina, choroid or iris, as well as blood flow rates determined with the hydrogen gas clearance method in the optic nerve head. The square blur ratio (SBR), another index for quantitative estimation of blood velocity, is proportional to the square of the NB. The SBR is theoretically a more exact measurement which is proportional to velocity, whereas the NB is an approximation. Normalized blur was calculated in earlier versions of LSFG because of technical limitations; the SBR is used in current versions of the LSFG instrument. As these values are in arbitrary units, they should not be used to make comparisons between different eyes or different sites in an eye. Clinical protocols, calibration, evaluation procedures and possible limitations of the LSFG technique are described and the results of ocular blood flow studies using LSFG are briefly summarized. The LSFG method is suitable for monitoring the time-course of change in the tissue circulation at the same site in the same eye at various intervals, ranging from seconds to months. Unresolved issues concern the effect of pupil size on measurement results, the effects of various stimulations, and how to measure choroidal and retinal blood flow velocity separately without using the blue-component of argon laser.

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“…Ca channel blockers have been found to increase blood flow in the ONH and choroid in animal studies 10,11 . Studies in humans with normal tension glaucoma (NTG) have shown a beneficial effect in preventing visual field loss by treatment with Ca channel blockers 12 .…”

Section: Introductionmentioning

confidence: 99%

“…Ca channel blockers have been found to increase blood flow in the ONH and choroid in animal studies. 10,11 Studies in humans with normal tension glaucoma (NTG) have shown a beneficial effect in preventing visual field loss by treatment with Ca channel blockers. 12 Whether the useful effects of the Ca channel blocker are mediated through actions on ganglion cells or indirectly through improvement of the ocular blood flow is unclear.…”

Section: Introductionmentioning

confidence: 99%