Uses of Ophthalmic Viscosurgical Devices
The space maintenance ability of OVDs keeps the anterior chamber formed despite the presence of 1 or more corneal incisions. With expansion of the chamber, manipulations can be made away from the corneal endothelium and posterior lens capsule. A cohesive OVD can be used to enlarge a marginally dilated pupil (viscomydriasis). It can also be used to keep the plane of the anterior capsule flat to assist a controlled continuous curvilinear capsulorrhexis. Lens implantation is less traumatic to the zonular fibers and the posterior capsule when the capsular bag is inflated with an OVD.
The coatability of OVDs can be used to protect the corneal endothelium from phacoemulsification energy, particularly in dense cataracts or during long operations. The surgeon must take care to remove dispersive OVDs completely to reduce the risk of an ocular hypertensive period caused by angle outflow obstruction. In the presence of an open posterior lens capsule, a dispersive OVD can be injected over the tear to provide a vitreous tamponade and prevent prolapse of vitreous anteriorly.
The optical clarity of OVDs has prompted some surgeons to use a layer of OVD on the surface of the cornea. When slightly moistened with balanced salt solution, the agent coats the epithelium. This maneuver prevents drying and eliminates the need to irrigate the corneal surface. It also provides a slightly magnified view of anterior segment structures.
Ultimately, the choice of OVD varies depending on the clinical scenario and surgeon preference. A survey showed that 97% of surgeons vary their choice of OVD in complicated cases. For example, in pediatric cataracts or cases with a low endothelial cell count, shallow anterior chamber, or IFIS, the choice of OVD can play a critical role in management. The preferred OVD for each surgical situation is a personal decision for each surgeon, guided by experience and product availability.
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.