Initial Observations on the Ocular Microcirculation in Man

Controlled vascular corrosion casting of the rabbit eye

“…These arteriolar branches are identifiable in this material by anatomical criteria rather than by the customary nuclear imprints alone (Hodde et al, 1977) and evince a singular propensity to respond to any physiological insult or administration of an appropriate drug with vasoconstriction at a crisply defined locale (Fahrenbach and Van Buskirk, 1987). Similar-appearing constrictions have also been observed in arterioles entering the choriocapillaris from short posterior ciliary arteries in man (Woodlief and Eifrig, 1982). The diameter at the constriction, evidently a contractile cuff just beyond the branching point of the arteriole from the MAC, was then compared to that of the same vessel about 50 pm downstream, that is, well beyond the region of the cuff, and the difference expressed as a percentage ([constricted diameterlnonconstricted diameter x 1001 -loo), with negative values indicating a constriction and positive values a gradual taper from the parent vessel.…”

Controlled vascular corrosion casting of the rabbit eye

“…These arteriolar branches are identifiable in this material by anatomical criteria rather than by the customary nuclear imprints alone (Hodde et al, 1977) and evince a singular propensity to respond to any physiological insult or administration of an appropriate drug with vasoconstriction at a crisply defined locale (Fahrenbach and Van Buskirk, 1987). Similar-appearing constrictions have also been observed in arterioles entering the choriocapillaris from short posterior ciliary arteries in man (Woodlief and Eifrig, 1982). The diameter at the constriction, evidently a contractile cuff just beyond the branching point of the arteriole from the MAC, was then compared to that of the same vessel about 50 pm downstream, that is, well beyond the region of the cuff, and the difference expressed as a percentage ([constricted diameterlnonconstricted diameter x 1001 -loo), with negative values indicating a constriction and positive values a gradual taper from the parent vessel.…”

Trypsin Digest of the Iris

“…Arti facts commonly arise with the casting tech nique as a result of postmortem blood clot ting, failure of polymerization of the plastic material, leakage of the material, and fragil ity of the vascular casts [3], Unlike trypsin digestion techniques, casting techniques yield meaningful results only if performed within several hours after death. Investiga tion of the iris vasculature by the casting technique was described in cats [9], rabbits [8], primates [4,6], and humans [7,12]. Our method allows the study of the vessel wall characteristics and can be applied to any specimen preserved in formalin.…”

Dynamics of external ocular blood flow studied by scanning angiographic microscopy

“…A primate study has suggested that an extensive collateral system may occur in the intramuscular circle between the anterior ciliary and long posterior ciliary circula tions,S although this has been disputed in two human studies. 6,7 It is generally accepted that the anterior ciliary arteries provide a major part of the vascular supply to the anterior uvea via their scleral perforating branches.1-3 This view is supported by the develop ment of anterior segment ischaemia following tenotomy of the vertical rectus muscles, particularly when combined with additional tenotomies,4,9-11 and by the results of studies involving corrosion vascular castings,5-8 the injection of labelled micro spheres,12,l3 and extraocular muscle tenotomies in primates.14-- 16 However, several investigations of the circulatory dynamics using segment fluorescein angiography have concluded that blood flow in the anterior ciliary arteries is principally centrifugal or retro grade in direction, [17][18][19][20][21][22][23][24][25] and that the anterior ocular surface is predominantly supplied from within the globe. These angiographic observations appear to be at odds with most of the non-angiographic clinical and experimental data.…”

Controlled vascular corrosion casting of the rabbit eye

“…These arteriolar branches are identifiable in this material by anatomical criteria rather than by the customary nuclear imprints alone (Hodde et al, 1977) and evince a singular propensity to respond to any physiological insult or administration of an appropriate drug with vasoconstriction at a crisply defined locale (Fahrenbach and Van Buskirk, 1987). Similar-appearing constrictions have also been observed in arterioles entering the choriocapillaris from short posterior ciliary arteries in man (Woodlief and Eifrig, 1982). The diameter at the constriction, evidently a contractile cuff just beyond the branching point of the arteriole from the MAC, was then compared to that of the same vessel about 50 pm downstream, that is, well beyond the region of the cuff, and the difference expressed as a percentage ([constricted diameterlnonconstricted diameter x 1001 -loo), with negative values indicating a constriction and positive values a gradual taper from the parent vessel.…”

Trypsin Digest of the Iris

“…Arti facts commonly arise with the casting tech nique as a result of postmortem blood clot ting, failure of polymerization of the plastic material, leakage of the material, and fragil ity of the vascular casts [3], Unlike trypsin digestion techniques, casting techniques yield meaningful results only if performed within several hours after death. Investiga tion of the iris vasculature by the casting technique was described in cats [9], rabbits [8], primates [4,6], and humans [7,12]. Our method allows the study of the vessel wall characteristics and can be applied to any specimen preserved in formalin.…”

Dynamics of external ocular blood flow studied by scanning angiographic microscopy

“…A primate study has suggested that an extensive collateral system may occur in the intramuscular circle between the anterior ciliary and long posterior ciliary circula tions,S although this has been disputed in two human studies. 6,7 It is generally accepted that the anterior ciliary arteries provide a major part of the vascular supply to the anterior uvea via their scleral perforating branches.1-3 This view is supported by the develop ment of anterior segment ischaemia following tenotomy of the vertical rectus muscles, particularly when combined with additional tenotomies,4,9-11 and by the results of studies involving corrosion vascular castings,5-8 the injection of labelled micro spheres,12,l3 and extraocular muscle tenotomies in primates.14-- 16 However, several investigations of the circulatory dynamics using segment fluorescein angiography have concluded that blood flow in the anterior ciliary arteries is principally centrifugal or retro grade in direction, [17][18][19][20][21][22][23][24][25] and that the anterior ocular surface is predominantly supplied from within the globe. These angiographic observations appear to be at odds with most of the non-angiographic clinical and experimental data.…”

Controlled vascular corrosion casting of the rabbit eye

“…These arteriolar branches are identifiable in this material by anatomical criteria rather than by the customary nuclear imprints alone (Hodde et al, 1977) and evince a singular propensity to respond to any physiological insult or administration of an appropriate drug with vasoconstriction at a crisply defined locale (Fahrenbach and Van Buskirk, 1987). Similar-appearing constrictions have also been observed in arterioles entering the choriocapillaris from short posterior ciliary arteries in man (Woodlief and Eifrig, 1982). The diameter at the constriction, evidently a contractile cuff just beyond the branching point of the arteriole from the MAC, was then compared to that of the same vessel about 50 pm downstream, that is, well beyond the region of the cuff, and the difference expressed as a percentage ([constricted diameterlnonconstricted diameter x 1001 -loo), with negative values indicating a constriction and positive values a gradual taper from the parent vessel.…”

Trypsin Digest of the Iris

“…Arti facts commonly arise with the casting tech nique as a result of postmortem blood clot ting, failure of polymerization of the plastic material, leakage of the material, and fragil ity of the vascular casts [3], Unlike trypsin digestion techniques, casting techniques yield meaningful results only if performed within several hours after death. Investiga tion of the iris vasculature by the casting technique was described in cats [9], rabbits [8], primates [4,6], and humans [7,12]. Our method allows the study of the vessel wall characteristics and can be applied to any specimen preserved in formalin.…”

Dynamics of external ocular blood flow studied by scanning angiographic microscopy

“…A primate study has suggested that an extensive collateral system may occur in the intramuscular circle between the anterior ciliary and long posterior ciliary circula tions,S although this has been disputed in two human studies. 6,7 It is generally accepted that the anterior ciliary arteries provide a major part of the vascular supply to the anterior uvea via their scleral perforating branches.1-3 This view is supported by the develop ment of anterior segment ischaemia following tenotomy of the vertical rectus muscles, particularly when combined with additional tenotomies,4,9-11 and by the results of studies involving corrosion vascular castings,5-8 the injection of labelled micro spheres,12,l3 and extraocular muscle tenotomies in primates.14-- 16 However, several investigations of the circulatory dynamics using segment fluorescein angiography have concluded that blood flow in the anterior ciliary arteries is principally centrifugal or retro grade in direction, [17][18][19][20][21][22][23][24][25] and that the anterior ocular surface is predominantly supplied from within the globe. These angiographic observations appear to be at odds with most of the non-angiographic clinical and experimental data.…”