ABSTRACT
Viscoelastic substances are solutions with dual properties; they act as viscous liquids as well as elastic solids or gels. The ideal viscoelastic substance in ophthalmology should be viscous enough to prevent collapse of the anterior chamber at rest, yet liquid enough to be injected precisely through a small cannula. It should be elastic or shock absorbing and should enhance coating yet has minimal surface activity. It should be cohesive enough to be removed to be easily removed from the anterior chamber but not so cohesive that it is aspirated during irrigation and aspiration, which would provide no protection to endothelial cells during surgical manipulations. It should be eliminated from the eye in the postoperative period without an effect on intraocular pressure.6-8,20,22,23
Viscosurgery was a term coined by Balazs10,11 to describe the use of these solutions that had viscous, elastic and pseudoplastic properties during and after surgical procedures. During viscosurgery, viscoelastic substances are used as a fluid or a soft surgical instrument. The viscoelastic sodium hyaluronate was first used in ophthalmic surgery in 1972, when it was introduced as a replacement for vitreous and aqueous humor.10,11 Since then ophthalmic surgical procedures had undergone considerable advancement. The use of viscoelastic materials has become commonplace in anterior and posterior segment surgeries. These agents facilitate delicate and often difficult intraocular manipulations during various ophthalmic surgical procedures. They are used during cataract surgery and intraocular lens (IOL) implantation to maintain the anterior chamber depth and capsular bag distention, thus creating and preserving working space for the ophthalmic surgeon. These agents are designed to protect the delicate corneal endothelial cells during the surgery.20
