High refractive index polysiloxane as Injectable, in situ curable accommodating intraocular lens

Abstract

Functionalised siloxane macromonomers, with properties designed for application as an injectable, in situ curable accommodating intraocular lens (A-IOL), were prepared via reequilibration of a phenyl group-containing polysiloxane of very high molecular weight with octamethylcyclotetrasiloxane (D4) and 2,4,6,8-tetra(n-propyl-3-methacrylate)-2,4,6,8-tetramethylcyclotetrasiloxane (D4AM) in toluene using trifluoromethanesulfonic acid as a catalyst. Hexaethyldisiloxane was used as an end group to control the molecular weight of the polymer. The generated polymers had a consistency suitable for injection into the empty lens capsule. The polymers contained a low ratio of polymerisable groups so that, in the presence of a photo-initiator, they could be cured on demand in situ within 5 minutes under irradiation of blue light to form an intraocular lens within the lens capsule. All resulting polysiloxane soft gels had a low elastic modulus and thus should be able to restore accommodation. The pre-cure viscosity and post-cure modulus of the generated polysiloxanes were controlled by the end group and D4AM concentrations respectively in the re-equilibration reactions. The refractive index could be precisely controlled by adjusting the aromatic ratio in the polymer to suit such application as an artificial lens. Lens stretching experiments with both human and non-human primate cadaver lenses of different ages refilled with polysiloxane polymers provided a significant increase in amplitude of accommodation (up to 4 D more than that of the respective natural lens). Both in vitro cytotoxicity study using L929 cell lines and in vivo biocompatibility study in rabbit models demonstrated the non-cytotoxicity and ocular biocompatibility of the polymer.

Use of an optical clearing agent to enhance the visibility of subsurface structures and lesions from tooth occlusal surfaces

“…Commercially available diphenyl methyl siloxane copolymer has an RI close to that of dental enamel. 39,40 Our results with a common dental transparent VPS impression material (RI ¼ 1.4) show remarkable improvement in visibility of subsurface structures around the fissure. The higher performance of the lower RI VPS impression material (RI ¼ 1.4) suggests that index matching is not the most important criterion for increasing optical penetration.…”

Biomaterials for ocular reconstruction

“…The capsular bag is filled with a gel that sets at body temperature [83][84][85]. These gels could replace conventional IOLs, and perhaps the incidence of PCO, as the gel fills the irregularly shaped lens capsule eliminating space for cell proliferation and migration.…”

Preparation and characterization of transparent and foldable polysiloxane‐poly(methyl methacrylate) membrane with a high refractive index

“…WDioxane38 88 WPHMS3ðn12Þ 60n174m1134 (4) where, A Si-H , A Dioxane , and A Si-CH3 were the areas of Si-H peak at 4.70 ppm, proton peak area of dioxane and the methyl group peaks connecting to silicone, respectively. W Dioxane and W PMHS were the weights of internal standard (dioxane) and sample of PMHS, respectively.…”

“…For example, Hao et al 4 synthesized polysiloxane with a high RI of 1.46 via re-equilibration of octamethylcyclotetrasiloxane (D 4 ) and phenyl-grafted siloxane copolymer, which was suitable for injectable in situ curable accommodating intraocular lens. Carbazole, a rigid fused ring molecule with specific photoelectric properties, can be also grafted on the side-chain of polysiloxane to improve RI value.…”

“…Combination of PDMS in PMMA network will decrease its RI value, and this may induce significant hyperopia due to RI mismatch. 4 The RI value of polysiloxane can be…”