2020–2021 BCSC Basic and Clinical Science Course™
11 Lens and Cataract
Chapter 7: Preoperative Considerations for Cataract Surgery
Ophthalmic Viscosurgical Devices
Ophthalmic viscosurgical devices (OVDs), also referred to as viscoelastic agents, have been employed in anterior segment surgery since 1979. They play an important role in maintaining the anterior chamber and protecting the corneal endothelium during surgery, and their use has had a profound influence on the evolution of extracapsular and phacoemulsification surgery.
OVDs contain 1 or more of the following substances in varying concentrations:
Sodium hyaluronate, a biopolymer that occurs in many connective tissues throughout the body, such as synovial (joint) fluid and vitreous. It was originally isolated from human umbilical cord and rooster combs. Sodium hyaluronate has a half-life of approximately 1 day in aqueous and 3 days in vitreous.
Chondroitin sulfate, a sulfated glycosaminoglycan, which is an important component of cartilage.
Hydroxypropyl methylcellulose (HPMC), which does not occur naturally in animal tissues; however, cellulose is widely distributed in plant fibers such as cotton and wood. The commercial product is a cellulose polymer modified by the addition of hydroxypropyl and methyl groups to increase the hydrophilic property of the material. Methylcellulose is a nonphysiologic compound that does not appear to be metabolized intraocularly. It is eventually eliminated in the aqueous but can easily be irrigated from the eye.
Excerpted from BCSC 2020-2021 series: Section 11 - Lens and Cataract. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.