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A combination ophthalmic viscosurgical device, 1.6% sodium hyaluronate, fills the bill during cataract surgery by combining the benefits of cohesive and dispersive agents in a single vial instead of two separate vials, making it more economical and simplifying surgery.
OVDs can be classified into two main categories: dispersive, which coat and protect ocular tissues; and cohesive, which are excellent for pressurizing the eye and maintaining space, explained Uday Devgan, MD, FACS.
"Ideally, the surgeon wants both of these characteristics," said Dr. Devgan, chief of ophthalmology, Olive View University of California Los Angeles (UCLA) Medical Center, associate clinical professor of ophthalmology, Jules Stein Eye Institute, UCLA, and in private practice at Devgan Eye Surgery, Los Angeles. "The syrupy dispersive coats and protects the corneal endothelium, and the thick cohesive keeps the eye inflated during creation of a capsulorhexis, the anterior chamber deep, and the capsule flat to avoid tearing the capsulorhexis. These properties are needed throughout the surgery."
Making the appropriate choice
"[The combination OVD of 1.6% sodium hyaluronate] has more versatility because it emulates two separate agents," Dr. Devgan said. "This OVD is a good cross between a pure dispersive OVD and a pure cohesive OVD. In routine cataract surgery cases, [the product] is a very appropriate choice."
In addition, a combination agent in one vial is less costly than a combination pack in which the OVDs are packaged separately and can be used for each stage of the phaco procedure.
In more challenging situations, such as those cases with ruptured capsules or broken zonules, Dr. Devgan suggested that a purely dispersive OVD might be a better choice. In the presence of intraoperative floppy iris syndrome, a super-cohesive OVD might be more beneficial.
"In my operating room, I keep the full spectrum of these agents available so that I can use the right tool for the job and give the patient the best surgical results," he said.
The OVD is injected as a wave across the pupil to achieve an exchange of fluid, with the aqueous coming out of the eye and being replaced fully with OVD. The eye is inflated to a physiologic IOP in most cases, or somewhat higher in eyes with a shallow anterior chamber to achieve flattening of the anterior lens capsule.