Viscoelastic Polymer
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VISCOELASTIC POLYMERS
BY :Varsha Jagdale
-: GUIDED BY :Mrs. Sapna Paul
DEFINITION
VISCOELASTIC NEED The endothelium gets damaged due to:
• CONTACT WITH AN ARTIFICIAL LENS. • BENDING OF CORNEA. • EXTENSIVE RUBBING OF THE ENDOTHELIUM WITH NATURAL LENS AND THROUGH CONTACT WITH INSTRUMENTS. • ULTRASONIC ENERGY BURN BY A PHACOEMULSIFICATION OF NUCLEUS.
FUNCTIONS OF VISCOELASTICS • STABILIZATION OF THE ANTERIOR CHAMBER. • PROTECTIVE EFFECT BY ADHERING ENDOTHELIUM, COATING IT DURING THE PROCEDURE. • AS A VITREOUS SUBSTITUTE IN CASE OF VITREOUS LOSS AND RETINAL DETACHMENT SURGERY.
CORNEAL PROTECTION • CAUSES : 1) MECHANICAL IRRITATION 2) BOMBARDNING OF LENS FRAGMENTS • DISPERSIVE SUBSTANCES:
VISCOELASTIC CAN BE USED IN FOUR WAYS
VISCOELASTICS USED IN EYES • • • • •
INERT AND ISO-OSMOTIC. OPTICALLY CLEAR. VISCOUS HYDROPHILIC AND DILUTABLE PROTECT THE CELLS, SEPARATE THE TISSUE AND MAINTAINS SPACE AND ACT AS A LUBRICANT.
HYDROXY PROPYL METHYLCELLULOSE
HYDROXY PROPYL METHYLCELLULOSE • THE BASIC MOLECULE IS d-GLUCOSE • TWO MOLECULES OF GLUCOSE COMBINE TO FORM CELLOBOISE WHICH DIFFERS FROM MALTOSE ONLY BY THE WAY THE TWO MOLECULES ARE STEREO CHEMICALLY ARRANGED. • IN CELLOBOISE THE BONDING IS BETAGLYCOSIDIC IN MALTOSE IT IS ALPHA GLYCOSIDIC
SODIUM HYALURONATE
For lens implantation, sodium hyaluronate may be used in four ways
CHONDROITIN SULFATE
PROBLEMS RELATED WITH VISCOELASTICS ONE MAJOR DRAWBACK OF VISCOELASTICS IS RETENATION OF THE SUBSTANCE AFTER SURGERY RESULTING IN INCREASED POSTOP INTRAOCULAR PRESSURE(IOP) IN SOME PATIENTS. WHEN THESE IOP’s ARE HIGH (i.e. SPIKES, DEFINED AS >30mmHg), OR THE PATIENT HAS GLAUCOMATOUS DISCS THIS BECOMES AN IMPORTANT ISSUE.
RHEOLOGY • THE FLOW OF NEWTONIAN FLUID IS EXPRESSED BY USING EQUATION ŋ=F/G F= Shear Stress G= Shear rate • ELASTICITY BEHAVIOUR IS EXPRESSED BY EXPRESSION FOR A SPRING E=F/γ E= Modulus of elasticity dyne/cm²) γ= The strain (dimensionless) F= The stress (dyne/cm²)
b) Spring
) Dashpot & Spring in series (Maxwell unit)
a) Dashpot
•
TYPES OF VISCOELASTICS COHESIVES :
ADVANTAGES : 1) BEST FOR MAINTAINING ANTERIOR CHAMBER, AND CREATING SPACE 2) EASY TO REMOVE BECAUSE OF HIGH SURFACE TENSION DISADVANTAGES: 1) CAN BE LOST IN LARGE AMOUNT THROUGH WOUND DURING CAPSULORRHEXIS IF THE WOUND IS OPEN 2) TEND TO GO AWAY WITH THE FIRST VACCUM AND DO NOT PROTECT THE ENDOTHELIUM WELL 15.
DISPERSIVES: ADVANTAGES: 1) BEST FOR PROTECTING THE CORNEAL ENDOTHELIUM IRIS
2) EFFECTIVE IN SEALING CAPSULAR TEAR AND KEEPING THE
DISADVANTAGES: 1) THEY DO NOT MAINTAIN SPACE WELL AND INCREASE RISK OF BURN IN PHACOEMULSIFICATION
•
PROPERTIES OF VISCOELASTICS
COHESION OR DISPERSION
FUNCTION OF BOTH ELASTICITY AND MOLECULAR LENGTH •
ELASTICITY
POSITIVELY CORRELATED WITH ITS MOLECULAR WEIGHT AND ZERO SHARE VISCOSITY
•
MOLECULAR CHARGE THE COATING ABILITY OF A VISCOELASTIC IS DETERMINED IN PART BY ITS MOLECULAR CHARGE
•
MOLECULAR WEIGHT DETERMINES ITS ENTIRE SPECTRUM OF PHYSICAL ATTRIBUTES
•
PHYSIOCHEMICAL PROPERTIES
•
PSEUDOPLASTICITY
•
SURFACE TENSION
•
VISCOSITY VISCOSITY AFFECTS THE VISCOELASTICS ABILITY TO MAINTAIN SPACE, TO SERVE AS A SOFT INSTRUMENTS FOR MANIPULATING TISSUE AND TO PROTECT THE CORNEAL ENDOTHELIUM.
PRODUCTS •
HEALON HEALON
GENERAL INFORMATION Vendor
Advanced Medical Optics, Inc. (AMO)
Item
Healon
Polymer Composition
1% sodium hyalouranale
Volume
0.4 mL, 0.55 mL, and 0.85 mL
Features
•It has a high molecular weight. •It is reported to be nonantigenic. • It does not cause inflammatory or foreign body reactions. •It has a high viscosity •Sterile, single-use 27G cannula included with each syringe. •The 1% solution of Healon is transparent is reported to remain in the anterior chamber for less than 6 days. •Protects corneal endothelial cells and other ocular structures
Resting State Viscosity
300,000 mpas
Molecular Weight
4 million Daltons
•
HEALON GV HEALON GV GENERAL INFORMATION
Vendor
Advanced Medical Optics, Inc. (AMO)
Item
Healon GV
Polymer Composition
1.4% sodium hyaluronate Composition
Volume
0.85 mLand 0.55 mL
Features
•Healon GV creates and maintains a deep anterior chamber, to facilitate manipulation inside the eye with reduced trauma to the corneal endothelium and other ocular tissues. •Expands the anterior chamber and flattens the anterior capsule to facilitate capsulorrhexis •Possesses the highest moleculare weight of any ophthalmic viscosurgical device •Absorbs forces associated with IOL implantation •Sterile, single-use 27G cannula included with each syringe •Healon GV also can be used to efficiently maneuver, separate and control ocular tissues.
Resting State Viscosity
3 million mPas
Molecular Weight
5 million Daltons
CELLUGEL CELLUGEL® GENERAL INFORMATION Vendor
Alcon Laboratories
Item
CelluGel®
Polymer Composition
2% hydroxypropyl methylcellulose
Volume
1.0 mL
Features
•1.0 mL fill size •Single-use cannula provided •No refrigeration required
Resting State Viscosity
30,000 ± 10,000 mPas
Molecular Weight
300,000 Daltons
VISCOAT VISCOAT® General Information Vendor
Alcon Laboratories
Item
VisCoat®
Polymer Composition
3% sodium hyaluronate, 4% chondroitin sulfate
Volume
0.50 ml
Features
•a highly retentive, dispersive viscoelastic characterized by low molecular weight, low pseudoplasticity and low surface tension •provides good space maintenance and excellent tissue protection.
Resting State Viscosity
40,000 ± 20,000 cps (at shear rate of 2 sec-1, 25° C)
Molecular Weight
medium molecular weight sodium chondroitin sulfate
AMVISC AMVISC®
General Information
Vendor
Bausch & Lomb
Item
Amvisc®
Polymer Composition
1% sodium hyaluronate Composition
Volume
0.5 ml or 0.8 ml
Features
•the right viscoelastic agent for the planned extracap technique •possesses sufficient viscosity for excellent chamber maintenance during lens removal. •highly cohesive so that complete removal at the end of the case is easily and quickly accomplished priced to compete with any sodium hyaluronate viscoelastic agents
Resting State Viscosity
100,000-300,000 centipoise
Molecular Weight
1.1-1.8 x106
6.OCUCOAT General Information Vendor
Bausch & Lomb
Item
Ocucoat
Polymer Composition
2% Hydroxypropyl Methylcellulose
Features
•2% Hydroxypropyl Methylcellulose solution •Especially well suited for high volume, small incision surgery •The low molecular weight of Ocucoat viscoelastic allows for rapid removal with minimal risk of elevated intraocular pressure •The clarity of Ocucoat permits an unobstructed view of the surgical field throughout capsulorhexis and phacoemusification Ocucoat is the least expensive viscoelastic alternative available and Ocucoat is the most lubricious viscoelastic agent on the market.
Resting State Viscosity
2 million mPas
Molecular Weight
low molecular weight of Ocucoat viscoelastic
HOW CATARACT SURGERY IS DONE • Intra-Capsular Cataract Extraction
• Viscoelastic in Anterior Chamber
IRIS
ACIOL
PCIOL
Foldable PCIOL
Unfolded Lens in Capsular Bag
Extra-Capsular Cataract Extraction
Kelman PhacoEmulsification (KPE)
Ultrasonic Removal Of Cataract
•
Major complications may include:
• - Endophthalmitis (severe infection inside the eye) • - Suprachoroidal Hemorrhage (severe bleeding inside the eye) • - Bullous Keratopathy (swelling of the cornea that cannot be reversed) • - Retinal Detachment •
Minor Complications may include:
• • • • • • •
-An irregular pupil shape - Iritis, inflammation or swelling Inside the eye - Off-centre lens placement - Retinal tear or retinal hole - Glaucoma, raised internal eye pressure - Macular Edema, swelling of the central retina - Secondary Cataract
THANK YOU
BY :Varsha Jagdale
-: GUIDED BY :Mrs. Sapna Paul
DEFINITION
VISCOELASTIC NEED The endothelium gets damaged due to:
• CONTACT WITH AN ARTIFICIAL LENS. • BENDING OF CORNEA. • EXTENSIVE RUBBING OF THE ENDOTHELIUM WITH NATURAL LENS AND THROUGH CONTACT WITH INSTRUMENTS. • ULTRASONIC ENERGY BURN BY A PHACOEMULSIFICATION OF NUCLEUS.
FUNCTIONS OF VISCOELASTICS • STABILIZATION OF THE ANTERIOR CHAMBER. • PROTECTIVE EFFECT BY ADHERING ENDOTHELIUM, COATING IT DURING THE PROCEDURE. • AS A VITREOUS SUBSTITUTE IN CASE OF VITREOUS LOSS AND RETINAL DETACHMENT SURGERY.
CORNEAL PROTECTION • CAUSES : 1) MECHANICAL IRRITATION 2) BOMBARDNING OF LENS FRAGMENTS • DISPERSIVE SUBSTANCES:
VISCOELASTIC CAN BE USED IN FOUR WAYS
VISCOELASTICS USED IN EYES • • • • •
INERT AND ISO-OSMOTIC. OPTICALLY CLEAR. VISCOUS HYDROPHILIC AND DILUTABLE PROTECT THE CELLS, SEPARATE THE TISSUE AND MAINTAINS SPACE AND ACT AS A LUBRICANT.
HYDROXY PROPYL METHYLCELLULOSE
HYDROXY PROPYL METHYLCELLULOSE • THE BASIC MOLECULE IS d-GLUCOSE • TWO MOLECULES OF GLUCOSE COMBINE TO FORM CELLOBOISE WHICH DIFFERS FROM MALTOSE ONLY BY THE WAY THE TWO MOLECULES ARE STEREO CHEMICALLY ARRANGED. • IN CELLOBOISE THE BONDING IS BETAGLYCOSIDIC IN MALTOSE IT IS ALPHA GLYCOSIDIC
SODIUM HYALURONATE
For lens implantation, sodium hyaluronate may be used in four ways
CHONDROITIN SULFATE
PROBLEMS RELATED WITH VISCOELASTICS ONE MAJOR DRAWBACK OF VISCOELASTICS IS RETENATION OF THE SUBSTANCE AFTER SURGERY RESULTING IN INCREASED POSTOP INTRAOCULAR PRESSURE(IOP) IN SOME PATIENTS. WHEN THESE IOP’s ARE HIGH (i.e. SPIKES, DEFINED AS >30mmHg), OR THE PATIENT HAS GLAUCOMATOUS DISCS THIS BECOMES AN IMPORTANT ISSUE.
RHEOLOGY • THE FLOW OF NEWTONIAN FLUID IS EXPRESSED BY USING EQUATION ŋ=F/G F= Shear Stress G= Shear rate • ELASTICITY BEHAVIOUR IS EXPRESSED BY EXPRESSION FOR A SPRING E=F/γ E= Modulus of elasticity dyne/cm²) γ= The strain (dimensionless) F= The stress (dyne/cm²)
b) Spring
) Dashpot & Spring in series (Maxwell unit)
a) Dashpot
•
TYPES OF VISCOELASTICS COHESIVES :
ADVANTAGES : 1) BEST FOR MAINTAINING ANTERIOR CHAMBER, AND CREATING SPACE 2) EASY TO REMOVE BECAUSE OF HIGH SURFACE TENSION DISADVANTAGES: 1) CAN BE LOST IN LARGE AMOUNT THROUGH WOUND DURING CAPSULORRHEXIS IF THE WOUND IS OPEN 2) TEND TO GO AWAY WITH THE FIRST VACCUM AND DO NOT PROTECT THE ENDOTHELIUM WELL 15.
DISPERSIVES: ADVANTAGES: 1) BEST FOR PROTECTING THE CORNEAL ENDOTHELIUM IRIS
2) EFFECTIVE IN SEALING CAPSULAR TEAR AND KEEPING THE
DISADVANTAGES: 1) THEY DO NOT MAINTAIN SPACE WELL AND INCREASE RISK OF BURN IN PHACOEMULSIFICATION
•
PROPERTIES OF VISCOELASTICS
COHESION OR DISPERSION
FUNCTION OF BOTH ELASTICITY AND MOLECULAR LENGTH •
ELASTICITY
POSITIVELY CORRELATED WITH ITS MOLECULAR WEIGHT AND ZERO SHARE VISCOSITY
•
MOLECULAR CHARGE THE COATING ABILITY OF A VISCOELASTIC IS DETERMINED IN PART BY ITS MOLECULAR CHARGE
•
MOLECULAR WEIGHT DETERMINES ITS ENTIRE SPECTRUM OF PHYSICAL ATTRIBUTES
•
PHYSIOCHEMICAL PROPERTIES
•
PSEUDOPLASTICITY
•
SURFACE TENSION
•
VISCOSITY VISCOSITY AFFECTS THE VISCOELASTICS ABILITY TO MAINTAIN SPACE, TO SERVE AS A SOFT INSTRUMENTS FOR MANIPULATING TISSUE AND TO PROTECT THE CORNEAL ENDOTHELIUM.
PRODUCTS •
HEALON HEALON
GENERAL INFORMATION Vendor
Advanced Medical Optics, Inc. (AMO)
Item
Healon
Polymer Composition
1% sodium hyalouranale
Volume
0.4 mL, 0.55 mL, and 0.85 mL
Features
•It has a high molecular weight. •It is reported to be nonantigenic. • It does not cause inflammatory or foreign body reactions. •It has a high viscosity •Sterile, single-use 27G cannula included with each syringe. •The 1% solution of Healon is transparent is reported to remain in the anterior chamber for less than 6 days. •Protects corneal endothelial cells and other ocular structures
Resting State Viscosity
300,000 mpas
Molecular Weight
4 million Daltons
•
HEALON GV HEALON GV GENERAL INFORMATION
Vendor
Advanced Medical Optics, Inc. (AMO)
Item
Healon GV
Polymer Composition
1.4% sodium hyaluronate Composition
Volume
0.85 mLand 0.55 mL
Features
•Healon GV creates and maintains a deep anterior chamber, to facilitate manipulation inside the eye with reduced trauma to the corneal endothelium and other ocular tissues. •Expands the anterior chamber and flattens the anterior capsule to facilitate capsulorrhexis •Possesses the highest moleculare weight of any ophthalmic viscosurgical device •Absorbs forces associated with IOL implantation •Sterile, single-use 27G cannula included with each syringe •Healon GV also can be used to efficiently maneuver, separate and control ocular tissues.
Resting State Viscosity
3 million mPas
Molecular Weight
5 million Daltons
CELLUGEL CELLUGEL® GENERAL INFORMATION Vendor
Alcon Laboratories
Item
CelluGel®
Polymer Composition
2% hydroxypropyl methylcellulose
Volume
1.0 mL
Features
•1.0 mL fill size •Single-use cannula provided •No refrigeration required
Resting State Viscosity
30,000 ± 10,000 mPas
Molecular Weight
300,000 Daltons
VISCOAT VISCOAT® General Information Vendor
Alcon Laboratories
Item
VisCoat®
Polymer Composition
3% sodium hyaluronate, 4% chondroitin sulfate
Volume
0.50 ml
Features
•a highly retentive, dispersive viscoelastic characterized by low molecular weight, low pseudoplasticity and low surface tension •provides good space maintenance and excellent tissue protection.
Resting State Viscosity
40,000 ± 20,000 cps (at shear rate of 2 sec-1, 25° C)
Molecular Weight
medium molecular weight sodium chondroitin sulfate
AMVISC AMVISC®
General Information
Vendor
Bausch & Lomb
Item
Amvisc®
Polymer Composition
1% sodium hyaluronate Composition
Volume
0.5 ml or 0.8 ml
Features
•the right viscoelastic agent for the planned extracap technique •possesses sufficient viscosity for excellent chamber maintenance during lens removal. •highly cohesive so that complete removal at the end of the case is easily and quickly accomplished priced to compete with any sodium hyaluronate viscoelastic agents
Resting State Viscosity
100,000-300,000 centipoise
Molecular Weight
1.1-1.8 x106
6.OCUCOAT General Information Vendor
Bausch & Lomb
Item
Ocucoat
Polymer Composition
2% Hydroxypropyl Methylcellulose
Features
•2% Hydroxypropyl Methylcellulose solution •Especially well suited for high volume, small incision surgery •The low molecular weight of Ocucoat viscoelastic allows for rapid removal with minimal risk of elevated intraocular pressure •The clarity of Ocucoat permits an unobstructed view of the surgical field throughout capsulorhexis and phacoemusification Ocucoat is the least expensive viscoelastic alternative available and Ocucoat is the most lubricious viscoelastic agent on the market.
Resting State Viscosity
2 million mPas
Molecular Weight
low molecular weight of Ocucoat viscoelastic
HOW CATARACT SURGERY IS DONE • Intra-Capsular Cataract Extraction
• Viscoelastic in Anterior Chamber
IRIS
ACIOL
PCIOL
Foldable PCIOL
Unfolded Lens in Capsular Bag
Extra-Capsular Cataract Extraction
Kelman PhacoEmulsification (KPE)
Ultrasonic Removal Of Cataract
•
Major complications may include:
• - Endophthalmitis (severe infection inside the eye) • - Suprachoroidal Hemorrhage (severe bleeding inside the eye) • - Bullous Keratopathy (swelling of the cornea that cannot be reversed) • - Retinal Detachment •
Minor Complications may include:
• • • • • • •
-An irregular pupil shape - Iritis, inflammation or swelling Inside the eye - Off-centre lens placement - Retinal tear or retinal hole - Glaucoma, raised internal eye pressure - Macular Edema, swelling of the central retina - Secondary Cataract
THANK YOU
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