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Dual-viscoelastic system ideal for cataract surgery
With so many OVD agents available, it can be difficult to find the right combination.
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Viscoelastics are surgical tools that have been developed to make cataract surgery safer and easier by protecting ocular structures, as well as keeping the eye formed and compartmentalized.
There are a variety of viscoelastics, also called ophthalmic viscosurgical devices (OVDs), that are available for use during cataract surgery.
 Uday Devgan |
Dispersive vs. cohesive
The two primary classes of OVDs are dispersives, which have a syrupy consistency similar to honey, and cohesives, which are more solid than liquid and have a consistency similar to jam or gelatin. The dispersive OVDs are great for coating the cornea and protecting the corneal endothelium from ultrasound-induced phaco trauma and the fluid currents used during cataract removal. The dispersives coat so well that they tend to remain in place during surgery, but then they are harder to intentionally remove at the end of the case.
The cohesive OVDs are great for maintaining space, holding tissue in place and pressurizing the anterior segment. The cohesives are particularly well-suited for flattening the anterior capsule and deepening the anterior chamber to facilitate capsulorrhexis creation. In addition, cohesive OVDs can deeply open an empty capsular bag for IOL implantation, and then they are easily removed at the end of the case.
 A capsulorrhexis has been created under a cohesive OVD, Healon GV (tinted yellow), for maximum control, resulting in a round and well-centered opening, even in this highly elastic capsule. The dispersive OVD, Healon D (tinted blue), is then injected to coat and protect the corneal endothelium before phacoemulsification. |
 After IOL insertion, the yellow-tinted cohesive Healon GV is seen in the capsular bag and at the iris plane, and the blue-tinted dispersive Healon D is coating the corneal endothelium and pushed toward the angle of the eye. All viscoelastic is removed at the end of the case to avoid postoperative pressure spikes. Images: Devgan U |
Dual-viscoelastic system
Because the dispersive OVDs and cohesive OVDs have such different properties, it is difficult to produce a single viscoelastic that has the best of both. These single-tube combination agents may be good choices for routine cases in experienced hands, but many surgeons will find it better to use a separate dispersive and cohesive.
Dual-viscoelastic systems are available from Advanced Medical Optics as the duo-OVD named Healon D+GV, which consists of Healon D (dispersive) and Healon GV (greater viscosity cohesive), and from Alcon Laboratories as Duovisc, which consists of Provisc (cohesive) and Viscoat (dispersive). In addition, separate tubes of viscoelastics from other manufacturers can be used, such as using Bausch & Lomb Amvisc (cohesive) and Ocucoat (dispersive).
At the beginning of the case, a cohesive OVD is used to deepen the anterior chamber and flatten the anterior lens capsule to facilitate capsulorrhexis creation. Then, hydrodissection of the cataract is performed, which causes some OVD to escape from the incision as the balanced salt solution is injected around the cataract. Before inserting the phaco probe, a dispersive OVD is injected to coat and protect the corneal endothelium during nucleus removal.
Steve A. Arshinoff, MD, FRCSC, teaches the soft shell technique, in which these two viscoelastics are injected at the same time, with the dispersive placed under the cornea and then the cohesive injected over the lens capsule. The key is to make sure that the dispersive OVD is retained during surgery and not easily washed out by the fluid currents created during phaco surgery.
Once the nucleus has been removed and the cortex cleaned from the capsular bag, it is time to insert the IOL. The eye is inflated with a cohesive OVD because it will widely open the capsular bag and keep the anterior chamber formed and pressurized during IOL insertion. Once the IOL is in position, the cohesive OVD is easily removed from behind the IOL, as well as from the anterior chamber. Thorough removal of viscoelastics is important to minimize the risk of postop pressure spikes induced by trabecular meshwork blockage by OVDs.
Using color-dyed OVDs in the lab
I recently had the opportunity to use color-dyed OVDs for better visualization during practice surgeries in the wet lab. I used a yellow-tinted cohesive OVD (Healon GV) and a lightly blue-tinted dispersive OVD (Healon D) during surgery on pig eyes. I used the yellow-tinted cohesive to flatten the capsule, and I was able to create a round, well-centered capsulorrhexis, even in the young, elastic capsules of the pig eyes. Next, I injected the blue-tinted dispersive to shield the cornea during phacoemulsification.
At the time of IOL insertion, there was still a protective coating of the dispersive OVD in the eye. As I injected the yellow-tinted cohesive OVD to inflate the eye, the blue-tinted dispersive OVD was pushed toward the angle. After the IOL was inserted, the cohesive OVD was easily removed; however, removal of the dispersive OVD required vacuuming the anterior chamber and angle. Using the color-dyed OVDs allows a clear understanding of their behavior in the eye during surgery.
One of our most important tools
OVDs have evolved cataract surgery into a safer, easier and more efficient surgery. We now have many varieties of OVDs from multiple manufacturers, but with so many choices, it is often challenging to choose one agent for every step of a routine cataract case. When teaching surgeons, I advise them to try all varieties of OVDs to find a combination that works best for them.
In my own practice, I have found more success in choosing a dual-viscoelastic combination for most cases. It allows me to use a cohesive OVD for space maintenance and compartmentalization, as well as a dispersive OVD for coating and protection. That is truly the best of both worlds.
References:
- Arshinoff SA. Dispersive-cohesive viscoelastic soft shell technique. J Cataract Refract Surg. 1999;25(2):167-173.
- Arshinoff SA, Jafari M. New classification of ophthalmic viscosurgical devices – 2005. J Cataract Refract Surg. 2005;31(11):2167-2171.
- Uday Devgan, MD, FACS, is in private practice at Devgan Eye Surgery in Los Angeles, Beverly Hills, and Newport Beach, California. Dr. Devgan is Chief of Ophthalmology at Olive View UCLA Medical Center and an Associate Clinical Professor at the Jules Stein Eye Institute at the UCLA School of Medicine. Dr. Devgan can be reached at 11600 Wilshire Blvd., Suite 200, Los Angeles, CA 90025; 800-337-1969; fax: 310-388-3028; e-mail: devgan@gmail.com; Web site: www.DevganEye.com. Dr.Devgan is a consultant to Abbott Medical Optics and Bausch & Lomb, and is a stockholder in Alcon Laboratories and formerly in Advanced Medical Optics.
