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Application of PMMA Surface Plasma Treatment for Ophthalmic Medical Materials

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03 Apr,2021

Application of PMMA Surface Plasma Treatment for Ophthalmic Medical Materials:
Polymethyl methacrylate began to be used as contact lens materials in the 2040s. Because PMMA has high refractive index, suitable hardness and good biological affinity, it is still widely used. However, PMMA has poor hydrophilicity, which can cause long-term eyelid closure and discomfort to the wearer. At the same time, its oxygen permeability is poor, serious can lead to complications. If the above disadvantages of PMMA can be overcome, the efficiency of its use can be greatly improved. The surface of PMMA lens was coated with acetylene, nitrogen and water plasma polymer to improve the material's hydrophilicity and reduce the adhesion of corneal epithelial cells. The addition of organosiloxane into the interlayer of the polymer can improve the air permeability of the material, but because of the hydrophobic nature of the siloxane itself, its moisture retention is reduced. The surface hydrophobic problem of silicon-containing polymers was treated by means of glow discharge generated by vacuum ionization cleaning machine. The PMMA surface was treated by vacuum plasma MMA and polysiloxane, the carbon content of PMMA surface was decreased, the oxygen content was increased, and the moisture retention was improved.

CRF Surface Plasma Treatment
Contact lenses made of silicone rubber are called "soft" lenses. Silicone rubber has good air permeability, soft texture, good mechanical elasticity and durability. Its disadvantage is that the viscosity is too large, hydrophobic, easy to penetrate. Plasma deposition of methane film on silicone rubber surface can improve the moisture of silicone rubber, reduce viscosity, reduce liquid permeability, and maintain its air permeability.
 

PMMA is widely used in surgery as intraocular lens graft material, but its contact with corneal epithelial cells can lead to damage of corneal epithelial cells. Hydrophilic monomers, such as hydroxyethyl isobutenate or N-vinylpyrrolidone, can be deposited on the surface of PMMA by vacuum plasma cleaning machine graft deposition or irradiation treatment. In the experiment, the static "contact" test between rabbit cornea and lens surface showed that the PMMA surface without plasma treatment could cause 10-30% cell damage, while the treated PMMA/HEMA composite surface could cause about 10% cell damage, and the PMMA/NVP composite surface could cause less than 10% cell damage. Plasma deposition on C3F8, HEMA and NVP films can significantly reduce the damage of corneal cells. In addition, the adhesion ability of NVP membrane on PMMA surface was significantly lower than that of PMMA.

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