Hydrogels / Applications in Opthamology

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Hydrogels /Applications in Opthamology
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Polyelectrolyte Hydrogels
Hydrophilic polymer chains containing positive or
negatively charged functional groups that
interact electrostatic interactions to form a
cross-linked network that attracts water
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Hylauronic Acid
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Polyelectrolyte Multilayers
Layer by layer deposition
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Alginate gels
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Enzyme Immobilization
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Cell Encapsulation
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Alginate gels
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Alginate gels
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Applications

• artificial tendon and cartilage
• wound healing dressings (Vigilon, Hydron,
• Gelperm)
• non-antigenic, flexible wound cover
• permeable to water and metabolites
• low-strength
• artificial kidney membranes
• artificial skin
• maxillofacial and sexual organ reconstruction
  materials
• vocal cord replacement

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Corning Ultra Low Attachment ProductsUnique hydrogel surface inhibits cell attachment
                                                      
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Hydrogels Applications

• Earliest biomedical application contact lenses
• good mechanical stability
• favorable refractive index
• high oxygen permeability
• needs hygienic maintenance
• unable to correct for astigmatism

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Acrylates
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Methacrylates
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Poly(methyl methacrylate)
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Poly(2-hydroxyethylmethacrylatepHEMA
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Hydrogels PHEMA

• The most widely used hydrogel
• water content similar to living tissues
• inert to biological processes
• shows resistance to degradation
• permeable to metabolites
• not absorbed by the body
• withstands sterilization by heat
• prepared in various shaped and forms

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Contact lens

• PMMA
• HEMA
• Fabrication methods
• Computer assisted cutting (lathe)-PMMA rods
• Spin casting-polymerization
• Molding-polymerization

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Intraocular lens

• PMMA
• HEMA
• Polymer backbone - mixture of PMMA and PHEMA
• Varying water contents
• Additives such as UV blockers

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Foldable IOL complications/explantations -
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Reasons for Revision Surgery

• Incorrect lens power seen most commonly
• Glare/optical aberrations
• Dislocation/decentration
• Late postoperative opacification

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IOL Optic Opacification

• Surface opacification
• Opacification within the substance of the optic
• Analysis of opacifications reveals presence of
  calcium
• Calcium staining
• Scanning electron microscopic analysis

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Accommodative IOL 1CU (HumanOptics)
Total diameter 9.7 mm