Ultrastructure of the iris

Fine Structural Evaluation of the Iris After Unilateral Treatment With Latanoprost in Patients Undergoing Bilateral Trabeculectomy (The Mainz II Study)

“…The scavaging phagocytes of the iris stroma are clump cells, and they engulf debris, including free melanin granules. 21,23 It seemed reasonable that greater mobilization of these cells would be a consequence of disordered melanin production; however, we found no association between clump cell incidence and latanoprost treatment.…”

Fine Structural Evaluation of the Iris After Unilateral Treatment With Latanoprost in Patients Undergoing Bilateral Trabeculectomy (The Mainz II Study)

“…The scavaging phagocytes of the iris stroma are clump cells, and they engulf debris, including free melanin granules. 21,23 It seemed reasonable that greater mobilization of these cells would be a consequence of disordered melanin production; however, we found no association between clump cell incidence and latanoprost treatment.…”

The Structural Layers of the Porcine Iris Exhibit Inherently Different Biomechanical Properties

“…This could be due to its porous nature and composition; most of the stroma is composed of short collagen fibrils meshwork with fibroblasts and melanosomes. 33 , 34 The stroma matrix deforms rapidly in both extension and compression as aqueous humour gets quickly displaced through its pores, reaching structural equilibrium within seconds. Conversely, the dilator muscle takes longer to reach biomechanical equilibrium, the simple bundles of smooth muscle cells 33 containing actin and myosin filaments passively extend irreversibly, until the filaments are activated to overlap and contract during pupil constriction.…”

“…However, it is theoretically possible to equate the passive biomechanical behavior of both the dilator and sphincter muscle because they are antagonistic tissues. The differences in speeds of pupil constriction and dilation suggest possible small tissue differences, perhaps due to different nerve innervations, but microscopic studies have shown that these muscles are typical smooth muscles, 33 and hence are likely to exhibit similar biomechanical properties. Moreover, a better approach would involve incorporating the biphasic poroviscoelastic (BPVE) constitutive model for the stroma tissue, which accounts for both viscoelasticity and permeability.…”

Irissometry: Effects of Pupil Size on Iris Elasticity Measured With Video-Based Feature Tracking

“…Second, the iris shape is determined by the antagonistic radial dilator and concentric sphincter muscles. 34 As the sphincter muscle lies in the pupillary region, on top of the radial muscles that cover both pupillary and ciliary regions, 35 , 36 it is not unlikely that the constrictor muscle causes the strongest anatomical changes in the pupillary region when activated.…”

Fine Structural Evaluation of the Iris After Unilateral Treatment With Latanoprost in Patients Undergoing Bilateral Trabeculectomy (The Mainz II Study)

“…The scavaging phagocytes of the iris stroma are clump cells, and they engulf debris, including free melanin granules. 21,23 It seemed reasonable that greater mobilization of these cells would be a consequence of disordered melanin production; however, we found no association between clump cell incidence and latanoprost treatment.…”

The Structural Layers of the Porcine Iris Exhibit Inherently Different Biomechanical Properties

“…This could be due to its porous nature and composition; most of the stroma is composed of short collagen fibrils meshwork with fibroblasts and melanosomes. 33 , 34 The stroma matrix deforms rapidly in both extension and compression as aqueous humour gets quickly displaced through its pores, reaching structural equilibrium within seconds. Conversely, the dilator muscle takes longer to reach biomechanical equilibrium, the simple bundles of smooth muscle cells 33 containing actin and myosin filaments passively extend irreversibly, until the filaments are activated to overlap and contract during pupil constriction.…”

“…However, it is theoretically possible to equate the passive biomechanical behavior of both the dilator and sphincter muscle because they are antagonistic tissues. The differences in speeds of pupil constriction and dilation suggest possible small tissue differences, perhaps due to different nerve innervations, but microscopic studies have shown that these muscles are typical smooth muscles, 33 and hence are likely to exhibit similar biomechanical properties. Moreover, a better approach would involve incorporating the biphasic poroviscoelastic (BPVE) constitutive model for the stroma tissue, which accounts for both viscoelasticity and permeability.…”

Irissometry: Effects of Pupil Size on Iris Elasticity Measured With Video-Based Feature Tracking

“…Second, the iris shape is determined by the antagonistic radial dilator and concentric sphincter muscles. 34 As the sphincter muscle lies in the pupillary region, on top of the radial muscles that cover both pupillary and ciliary regions, 35 , 36 it is not unlikely that the constrictor muscle causes the strongest anatomical changes in the pupillary region when activated.…”

Fine Structural Evaluation of the Iris After Unilateral Treatment With Latanoprost in Patients Undergoing Bilateral Trabeculectomy (The Mainz II Study)

“…The scavaging phagocytes of the iris stroma are clump cells, and they engulf debris, including free melanin granules. 21,23 It seemed reasonable that greater mobilization of these cells would be a consequence of disordered melanin production; however, we found no association between clump cell incidence and latanoprost treatment.…”

The Structural Layers of the Porcine Iris Exhibit Inherently Different Biomechanical Properties

“…This could be due to its porous nature and composition; most of the stroma is composed of short collagen fibrils meshwork with fibroblasts and melanosomes. 33 , 34 The stroma matrix deforms rapidly in both extension and compression as aqueous humour gets quickly displaced through its pores, reaching structural equilibrium within seconds. Conversely, the dilator muscle takes longer to reach biomechanical equilibrium, the simple bundles of smooth muscle cells 33 containing actin and myosin filaments passively extend irreversibly, until the filaments are activated to overlap and contract during pupil constriction.…”

“…However, it is theoretically possible to equate the passive biomechanical behavior of both the dilator and sphincter muscle because they are antagonistic tissues. The differences in speeds of pupil constriction and dilation suggest possible small tissue differences, perhaps due to different nerve innervations, but microscopic studies have shown that these muscles are typical smooth muscles, 33 and hence are likely to exhibit similar biomechanical properties. Moreover, a better approach would involve incorporating the biphasic poroviscoelastic (BPVE) constitutive model for the stroma tissue, which accounts for both viscoelasticity and permeability.…”

Irissometry: Effects of Pupil Size on Iris Elasticity Measured With Video-Based Feature Tracking

“…Second, the iris shape is determined by the antagonistic radial dilator and concentric sphincter muscles. 34 As the sphincter muscle lies in the pupillary region, on top of the radial muscles that cover both pupillary and ciliary regions, 35 , 36 it is not unlikely that the constrictor muscle causes the strongest anatomical changes in the pupillary region when activated.…”