One of the earliest uses of HA as a biomaterial was as an aid during eye surgery. These viscoelastic agents, referred to as ophthalmic viscosurgical devices (OVDs) were a key development in making cataract surgery safer and recovery faster.
This is particularly true for various versions of the Kelman phacoemulsification method, one of the safest and most effective surgical procedures performed today. What was previously the leading cause of blindness can usually be rectified in less than an hour in a physicians office, with a success rate well over 90%. Vision is restored by removing the cataract and implanting an artificial intraocular lens (IOL). More than 1.5 million cataract surgeries are performed in the United States each year.
During surgery, the OVDs help coat and protect delicate surfaces inside the eye, such as the delicate inner surface of the cornea, from collateral damage. OVDs also help maintain the shape of the eye, allowing the surgeon better visualization and access to the small area in which he or she is working. They are also used to lubricate the surface of the IOL and the inside of the lens injector and to create a space within the capsular bag for precise placement of the IOL. In addition to cataract removal, OVDs have become essential in treating a variety of other eye conditions such as damage to the cornea or glaucoma.
Compatibility of HA with the tissues of the eye is excellent, since HA is a major component of the vitreous humor, the gel-like fluid that fills the rear chamber of the eye. An example of the placement of an OVD in the anterior chamber of the eye during the first stage of cataract surgery is shown in the figure below.
During the different stages of an eye surgery, the mechanical properties of the OVD must be matched to the performance requirements. For example, at one point one may need the OVD to provide a good coating for the surgical instruments, at another point it is desirable for the OVD to have a gel-like character to allow for complete removal from the eye in a single “piece”.
Anika manufactures AMVISC® and AMVISC® Plus OVDs, which are marketed by Bausch & Lomb. These high-purity products are carefully designed to provide an excellent balance of physical characteristics, allowing them to be used in a wide variety of applications. This simplifies the task of the surgeon, often obviating the need for a variety of OVDs to be employed at different stages.