Effects of Biological Stimuli on the Viscosity of the Vitreous

Abstract

Changes in the physical properties of the vitreous induced by various biological stimuli were investigated with Cannon-Fenske kinematic and cone-plate rotary viscometers. Heating greatly decreased the viscosity of the human vitreous, the critical temperature being between 50 degrees C and 60 degrees C. Freezing also affected the viscosity, but less so than heating. Viscosity of hyaluronic acid was also decreased by heating to approximately 60 degrees C. Preliminary incubation with hyaluronidase made the viscosity of both the vitreous and hyaluronic acid heat-stable. Lens extraction decreased vitreous viscosity markedly, suggesting a decrease of hyaluronic acid concentration and/or a lowering of hyaluronic acid molecular weight. Vitreous haemorrhage resulted in decreased vitreous viscosity. Cryoretinopexy at the level employed in this study induced little change in vitreous viscosity, while retinal diathermy caused a moderate decrease. In the course of vitreous haemorrhage and retinal diathermy, a return towards normal of the viscosity was observed, suggesting the presence of local hyaluronic acid production.

Insight into vitreous biomechanics and clinical implications: A systematic review

“…The most frequently used experimental models were porcine (n = 20, 33.3%)[27,29,30,33,35,37,39,41,43–48,50,51,54,55,57] and bovine/calf/cattle eyes (n = 15, 25.0%)[19,21,23,27,29,31,32,37,39,45,46,53,58]. Human eyes were used in 9 studies (15.0%)[22,33,35,36,40,42,45,46], followed by rabbit eyes (n = 8, 13.3%)[17,18,24,28,34,37,42,52]. Less common models included goat (n = 2, 3.3%)[37,49], monkey (n = 2, 3.3%)[25,52], sheep (n = 2, 3.3%)[26,37,46], owl (n = 1, 1.7%)[20], and ox (n = 1, 1.7%)[56].…”

“…Nine studies measured the viscosity of human vitreous humor using various methods and devices ( Table 3 )[21,33,35,36,38,40,42,45,46]. In 1964, Berman and Michaelson measured the relative viscosity of post- mortem human eyes using a Cannon-Manning semimicro capillary viscometer, reporting a viscosity of 1.04 for infants (0-2 years), 1.53 for individuals aged 13-45 years, and 2.08 for those aged 50-85 years, with myopic eyes showing a viscosity of 1.54 [21].…”

“…Locke and Morton (1965) analyzed 176 human eye samples with an Ostwald-type viscosimeter, finding an average viscosity of 1.97, with a range from 10.6 to 5.50 [36]. Kawano et alemployed a Cannon-Fenske kinematic viscometer and cone-plate rotary viscometer in 1982, confirming that the addition of 0.005% thimerosal did not affect the viscosity of the vitreous [33].…”

Insight into vitreous biomechanics and clinical implications: A systematic review

“…The most frequently used experimental models were porcine (n = 20, 33.3%)[27,29,30,33,35,37,39,41,43–48,50,51,54,55,57] and bovine/calf/cattle eyes (n = 15, 25.0%)[19,21,23,27,29,31,32,37,39,45,46,53,58]. Human eyes were used in 9 studies (15.0%)[22,33,35,36,40,42,45,46], followed by rabbit eyes (n = 8, 13.3%)[17,18,24,28,34,37,42,52]. Less common models included goat (n = 2, 3.3%)[37,49], monkey (n = 2, 3.3%)[25,52], sheep (n = 2, 3.3%)[26,37,46], owl (n = 1, 1.7%)[20], and ox (n = 1, 1.7%)[56].…”

“…Nine studies measured the viscosity of human vitreous humor using various methods and devices ( Table 3 )[21,33,35,36,38,40,42,45,46]. In 1964, Berman and Michaelson measured the relative viscosity of post- mortem human eyes using a Cannon-Manning semimicro capillary viscometer, reporting a viscosity of 1.04 for infants (0-2 years), 1.53 for individuals aged 13-45 years, and 2.08 for those aged 50-85 years, with myopic eyes showing a viscosity of 1.54 [21].…”

“…Locke and Morton (1965) analyzed 176 human eye samples with an Ostwald-type viscosimeter, finding an average viscosity of 1.97, with a range from 10.6 to 5.50 [36]. Kawano et alemployed a Cannon-Fenske kinematic viscometer and cone-plate rotary viscometer in 1982, confirming that the addition of 0.005% thimerosal did not affect the viscosity of the vitreous [33].…”

A promising approach in laser vitrectomy executed by plasma-mediated removal of vitreous body via a diode-pumped Q-switched Nd:YAG laser

“…Hyaluronic acid and collagen are the major components of the fiber matrix and responsible for the gel-like structure of the vitreous body; these components are, however, not homogeneously distributed 32 . The vitreous body is classified as a viscoelastic material and exhibits non-Newtonian rheological properties 32 – 34 , stemming from the varying concentrations of hyaluronic acid and collagen in the anterior, central and posterior regions 35 . Moreover, differences in the matrix composition mentioned above are responsible for the particular rheologic state of the vitreous in different species 36 .…”

“…Other data are given as apparent viscosities adopted to non-Newtonian fluids. In that case, the viscosity η depends additionally on the shear rate δ or the shear stress σ 34 . This involves a spatial separation of the viscosity measurements within the anterior, central and posterior regions of the vitreous body 32 , 37 , 39 .…”

Insight into vitreous biomechanics and clinical implications: A systematic review

“…The most frequently used experimental models were porcine (n = 20, 33.3%)[27,29,30,33,35,37,39,41,43–48,50,51,54,55,57] and bovine/calf/cattle eyes (n = 15, 25.0%)[19,21,23,27,29,31,32,37,39,45,46,53,58]. Human eyes were used in 9 studies (15.0%)[22,33,35,36,40,42,45,46], followed by rabbit eyes (n = 8, 13.3%)[17,18,24,28,34,37,42,52]. Less common models included goat (n = 2, 3.3%)[37,49], monkey (n = 2, 3.3%)[25,52], sheep (n = 2, 3.3%)[26,37,46], owl (n = 1, 1.7%)[20], and ox (n = 1, 1.7%)[56].…”

“…Nine studies measured the viscosity of human vitreous humor using various methods and devices ( Table 3 )[21,33,35,36,38,40,42,45,46]. In 1964, Berman and Michaelson measured the relative viscosity of post- mortem human eyes using a Cannon-Manning semimicro capillary viscometer, reporting a viscosity of 1.04 for infants (0-2 years), 1.53 for individuals aged 13-45 years, and 2.08 for those aged 50-85 years, with myopic eyes showing a viscosity of 1.54 [21].…”

“…Locke and Morton (1965) analyzed 176 human eye samples with an Ostwald-type viscosimeter, finding an average viscosity of 1.97, with a range from 10.6 to 5.50 [36]. Kawano et alemployed a Cannon-Fenske kinematic viscometer and cone-plate rotary viscometer in 1982, confirming that the addition of 0.005% thimerosal did not affect the viscosity of the vitreous [33].…”

A promising approach in laser vitrectomy executed by plasma-mediated removal of vitreous body via a diode-pumped Q-switched Nd:YAG laser

“…Hyaluronic acid and collagen are the major components of the fiber matrix and responsible for the gel-like structure of the vitreous body; these components are, however, not homogeneously distributed 32 . The vitreous body is classified as a viscoelastic material and exhibits non-Newtonian rheological properties 32 – 34 , stemming from the varying concentrations of hyaluronic acid and collagen in the anterior, central and posterior regions 35 . Moreover, differences in the matrix composition mentioned above are responsible for the particular rheologic state of the vitreous in different species 36 .…”

“…Other data are given as apparent viscosities adopted to non-Newtonian fluids. In that case, the viscosity η depends additionally on the shear rate δ or the shear stress σ 34 . This involves a spatial separation of the viscosity measurements within the anterior, central and posterior regions of the vitreous body 32 , 37 , 39 .…”

Insight into vitreous biomechanics and clinical implications: A systematic review

“…The most frequently used experimental models were porcine (n = 20, 33.3%)[27,29,30,33,35,37,39,41,43–48,50,51,54,55,57] and bovine/calf/cattle eyes (n = 15, 25.0%)[19,21,23,27,29,31,32,37,39,45,46,53,58]. Human eyes were used in 9 studies (15.0%)[22,33,35,36,40,42,45,46], followed by rabbit eyes (n = 8, 13.3%)[17,18,24,28,34,37,42,52]. Less common models included goat (n = 2, 3.3%)[37,49], monkey (n = 2, 3.3%)[25,52], sheep (n = 2, 3.3%)[26,37,46], owl (n = 1, 1.7%)[20], and ox (n = 1, 1.7%)[56].…”

“…Nine studies measured the viscosity of human vitreous humor using various methods and devices ( Table 3 )[21,33,35,36,38,40,42,45,46]. In 1964, Berman and Michaelson measured the relative viscosity of post- mortem human eyes using a Cannon-Manning semimicro capillary viscometer, reporting a viscosity of 1.04 for infants (0-2 years), 1.53 for individuals aged 13-45 years, and 2.08 for those aged 50-85 years, with myopic eyes showing a viscosity of 1.54 [21].…”

“…Locke and Morton (1965) analyzed 176 human eye samples with an Ostwald-type viscosimeter, finding an average viscosity of 1.97, with a range from 10.6 to 5.50 [36]. Kawano et alemployed a Cannon-Fenske kinematic viscometer and cone-plate rotary viscometer in 1982, confirming that the addition of 0.005% thimerosal did not affect the viscosity of the vitreous [33].…”

A promising approach in laser vitrectomy executed by plasma-mediated removal of vitreous body via a diode-pumped Q-switched Nd:YAG laser

“…Hyaluronic acid and collagen are the major components of the fiber matrix and responsible for the gel-like structure of the vitreous body; these components are, however, not homogeneously distributed 32 . The vitreous body is classified as a viscoelastic material and exhibits non-Newtonian rheological properties 32 – 34 , stemming from the varying concentrations of hyaluronic acid and collagen in the anterior, central and posterior regions 35 . Moreover, differences in the matrix composition mentioned above are responsible for the particular rheologic state of the vitreous in different species 36 .…”

“…Other data are given as apparent viscosities adopted to non-Newtonian fluids. In that case, the viscosity η depends additionally on the shear rate δ or the shear stress σ 34 . This involves a spatial separation of the viscosity measurements within the anterior, central and posterior regions of the vitreous body 32 , 37 , 39 .…”