Transcript Document

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
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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 Products
Unique 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-hydroxyethylmethacrylate
pHEMA
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Hydrogels: PHEMA
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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
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PMMA
HEMA
Fabrication methods
 Computer assisted cutting (lathe)-PMMA rods
 Spin casting-polymerization
 Molding-polymerization
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Intraocular lens
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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 Survey Lens Totals
2001
9%
25%
8%
14%
28%
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Multifocal,Silicone
One Piece (plate),Silicone
One Piece with Haptics,Acrylic
Three Piece,Acrylic
Three Piece,Hydrogel
Three Piece,Silicone
16%
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Reasons for Revision Surgery
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Incorrect lens power seen most commonly
Glare/optical aberrations
Dislocation/decentration
Late postoperative opacification
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IOL Optic Opacification
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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
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