Viscoelastics in Ophthalmic Surgery

ISBN-13: 9783642641220 / Angielski / Miękka / 2012 / 152 str.

H. B. Dick; O. Schwenn

Opis

It will be difficult to find an ophthalmic surgeon who will gladly do his work entirely without viscoelastics. Within just a few years this group of substances has enlarged the field of ophthalmic surgery enormously. Many procedures have be come safer and simpler and other techniques could only be developed because of the availability of visco elastics. Especially cataract surgery and implantation of intraocular lenses have benefitted. Implantation of an intraocular lens can be per formed much more reliably into the capsular bag without endangering the posterior capsule. Implantation of foldable lenses would be almost impossible without visco elastics. However, other surgical maneuvers also necessitate visco elastics, especially when the anterior chamber must be maintained, the corneal endothelium must be protected and delicate tissues must be manipulated. A cor neal transplant can be sutured safely into the recipient corneal ring using visco elastics. Even in glaucoma surgery, visco elastics gain importance as they are being used in trabeculectomy or in deep sclerectomy with additional viscocana lostomy. But which substance is best for which purpose? Just as much as a basic phar macological knowledge is necessary for a rational use of drugs, in-depth know ledge of physicochemical properties and objective investigations are prerequi sites for a logical selection of visco elastics from an ever increasing number of available substances. H."

Spis treści

1 Overview.- Historical Development.- Current Breakdown of Viscoelastic Substances.- Analysis of Current Application Modes.- 2 Basics.- Physicochemical Properties of Ophthalmic Viscosurgical Devices.- • Flow Characteristics.- • Viscosity.- • Influence of the Shear Rate on Viscosity.- • Elasticity.- • Viscoelasticity.- • Pseudoplasticity.- • Coatability.- • Rigidity.- • Cohesiveness.- Optical Properties of Viscoelastic Substances.- Chemical Properties of Viscoelastic Substances, Biocompatibility and Safety Requirements.- • pH-Value.- • Colloid Osmotic Pressure.- • Osmolality.- • Structural Formulas and Chemical Composition.- • Complications Through Viscoelastics.- • The Owl Monkey Eye Test.- • International Organization for Standardization.- 3 Viscoelastic Substances.- Hyaluronate.- Hydroxypropylmethylcellulose.- Chondroitin Sulfate.- Polyacrylamide.- Collagen.- Cellugel®.- 4 Product Specifications.- Manufacturers’ Information About Their Viscoelastics.- Our Own Comparative Trials.- • Zero Shear Viscosity.- • Pseudoplasticity.- • Relaxation Time.- • Intersection G?/G? (Elasticity Modulus/Viscosity Modulus).- • pH-Value.- 5 General Applications of Viscoelastics.- Maintenance of the Anterior Chamber.- • Injection Techniques Into a Deep Anterior Chamber.- • Injection Techniques Into a Collapsed Anterior Chamber.- Tissue Manipulations.- • Viscomydriasis.- • Facilitating Lens Implantation.- Coatability.- Corneal Endothelial Protection.- Hemostasis.- Management of Complications.- 6 Complications Through the Use of Viscoelastics.- Therapy for Raised IOP Following Phacoemulsification.- 7 Special Uses of Viscoelastics.- Cataract Surgery.- • Routine.- • Complications and Difficult Situations.- • “Soft-Shell” Technique.- • “Best of Both Worlds” Technique.- Implantation of Foldable IOLs.- Perforating and Lamellar Keratoplasty.- Glaucoma Surgery.- Trauma Surgery.- Posterior Segment Surgery.- Surgery of Eye Muscles.- Lacrimal Dysfunction (Coating Medium).- 8 Removal of ViscoelasticSubstances.- The “Rock and Roll” Technique.- Retention of the Viscoelastic Substance.- 9 Healon®5: A New Viscoadaptive Formulation.- 10 Aseptic Production vs. Terminal Sterilization.- 11 Viscoelastics: Medical Device or Drug.- 12 Summary.- Product Overview.- • Hyaluronic Acid Products.- • HPMC-Products.- Measured Values for Certain Products Gained by Individual Investigations.- • Viscoelastics Containing Hyaluronic Acid.- • Viscoelastics from Hydroxypropylmethylcellulose.- References.

Blurb

This book presents the basic facts of viscoelastic substances. It introduces new, self-obtained data regarding viscoelastic rheological properties and describes the selective usages of viscoelastics in ophthalmic surgery. A clear and understandable presentation of viscoelastic physicochemical properties is emphasized to provide the practicing ophthalmic surgeon a reference guide for the selection of a suitable viscoelastic. The authors detail the broad range of viscoelastic applications, the latest trends in visco-surgery, and describe the complications arising from different surgical techniques with certain viscoelastics. Information on the production of viscoelastic substances is also included. Tables and figures are used to document research results and facilitate understanding, while a subject index and an extensive bibliography provide easy references. This book systematically presents basic knowledge and offers insight into the lastest applications in surgery as well as the most recent, relevant findings in the field of viscoelastic research.