Viscoelastic Choice

My current preference in viscoelastics is a dual combination of Vitrax (Allergan, Irvine, CA) and BioLon (Akorn, Inc. Buffalo Grove, IL). The DuoVisc (Alcon, Fort Worth, TX) system composed of Viscoat and ProVisc is a close second. The Vitrax/BioLon combination provides me with an ample volume of viscoelastic, two distinctly different agents with different properties, and a cost-effective solution.

From the perspective of volume, I delegate extra tasks to the viscoelastics to make the case easier. First, I use a cohesive agent such as BioLon or ProVisc to decrease the likelihood that the IOL will self-adhere in the folded position with forceps insertion. I coat the IOL prior to the beginning of the case, and set it on the side table. This allows the viscoelastic to remain on the surface of the lens for approximately 4 minutes, and nearly eliminates the tendency of the folded lens to stick to itself when released in the capsular bag. In theory, the larger-molecular-weight viscoelastic interferes with the molecular forces of the unbound acrylic monomers, hindering their attraction. For me, it just seems to work.

Secondly, I use the dispersive Vitrax or Viscoat to coat the cornea prior to surgery in a fashion described by Dr. Shugar. A thin layer in the shape of a pretzel approximately 5 mm in diameter is applied to the dry cornea just before beginning the case. Wetting this layer allows the viscoelastic to melt slowly, which keeps the cornea crystal-clear for the duration of the case without rewetting (Figures 1 and 2). The layer masks the occasional occurrence of epithelial haze, provides a mild degree of magnification for the capsulorhexis, and my surgical technicians particularly enjoy the freedom from the frequent call to “squirt the cornea.”

Like most surgeons, I find that the dispersive viscoelastics are great for filling the anterior chamber to facilitate controlled capsulorhexis creation, and they also provide endothelial protection during phacoemulsification. Although a cohesive viscoelastic is much better for filling the capsule for IOL implantation, primarily because it is easier to remove, these agents have a tendency to express themselves out of the wound when the posterior lip of the incision is depressed to insert the IOL. This expression significantly shallows the anterior chamber, and in my experience, excessive reflux has caused the unfolding haptics to catch on and tear the posterior capsule on at least two occasions. To avoid this problem, I fully distend the capsule with BioLon or ProVisc until I see viscoelastic overfill out of the incision. I then use either Vitrax or Viscoat to plug the primary incision and sideport, and I find this dispersive plug has considerably reduced the reflux of viscoelastic from the incision as I try to insert the IOL.

Using two separate tubes of viscoelastic (Vitrax and BioLon) rather than one combination product has made managing volume considerably easier. I can use a greater amount of each type, which leaves more available at the end of the case should it be useful. And in the event that a tube accidentally slips to the floor instead of the surgical field, only one tube needs to be opened as a replacement. With a combination product, I frequently need miniscule additional amounts of one of the agents during the case, especially at the end. Do I need a touch of the dispersive to keep the prolapsing iris away from the incision, or a touch of the cohesive to further deepen the capsule to insert the IOL? I quickly tired of being reminded of the cost of opening an expensive dual-tube product just to use a tiny amount.

The Right Combination

Satish Modi, MD
Cohesive viscoelastic agents (such as Healon [Pharmacia Corporation, Peapack, NJ], Amvisc [Bausch & Lomb, Rochester, NY] and ProVisc [Alcon Surgical, Ft. Worth, TX]) tend to be effective at creating space in the eye, but under shear forces, are easily removed en masse. Dispersive agents (such as Viscoat [Alcon Laboratories, Fort Worth, TX]) on the other hand, resist shearing forces very well, as they remain in the eye and protect its vital structures.

I employ a high-flow phacoemulsification technique using the Series 20000 Legacy with NeoSonix (Alcon Surgical); I routinely utilize a flow rate of 50 mL/min. The advantages of high flow include decreased ultrasound time and a speedier surgery. However, it is easy to forget that these advantages translate into the flushing of 200 times the volume of the anterior chamber every minute. I need a viscoelastic that can resist the large shear forces generated by this high flow so that it can stay in the eye and protect the endothelium from the turbulence of phacoemulsification. In my experience, only Viscoat provides this protection.

We conducted a prospective study of the protective effects of Healon GV, Amvisc Plus, and Viscoat. Our main outcome parameters were postoperative presence of increased pachymetry, decreased endothelial cell count, presence of corneal striae, and best-corrected acuity. These were 60 uncomplicated cases with the same average ultrasound time. The parameters were measured at 1 day, 1 week, 1 month, 3 months, 6 months, and 1 year postoperatively. At 3 months, the Viscoat cases had 0% striae and 100% of the cases had 20/25 or better BCVA. The cohesive patients showed striae in 10 to 20% of patients, and only 85 to 90% of the patients had BCVA of 20/25.

The study results that were most telling were the endothelial cell counts: at 1 year, there was a 10% decrease with Healon, 14% with Amvisc Plus and only 4% with Viscoat. Lower endothelial cell counts enable patients to see better and earlier, which is a very important factor in this day of managed care and outcome analyses.

Unfortunately, with Viscoat, the very property that allows it to coat the corneal endothelium so well is a detriment to removing it at the end of the case. It used to take me more than 2 minutes to remove Viscoat, and I would still see IOP spikes as high as 40 mm Hg the next day.

ProVisc, the other cohesive viscoelastic in the DuoVisc combo from Alcon Surgical, has solved that problem. ProVisc allows me to fill the capsular bag beautifully (as one would expect from a cohesive agent), enabling easy placement of the IOL. Once implanted, it is easily removed in 10 to 12 seconds—I do not have to go through the cumbersome process of aspirating beneath the implant, and my patients have not experienced any pressure spikes on the following day.

I contend that there is no single viscoelastic that can do everything we require within the eye. I invariably end up compromising when I use just one agent. With DuoVisc, however, I do not have to compromise; I enjoy the benefits of a proven dispersive agent (Viscoat) along with a cohesive agent (ProVisc).

A Visco For Posterior Phaco

Douglas A. Katsev, MD
The viscoelastic that I use 100% of the time is Healon5 (Pharmacia Corporation, Peapack, NJ). It is my viscoelastic of choice because pupil dilation creates an extra 1 to 3 mm of viewing area to facilitate cataract surgery. Another advantage of this agent lies in controlling the capsulorhexis. The capsulorhexis is often smaller in the surgeon's first two cases because of the high anterior chamber pressure. The tear is slightly slower, and this thicker viscoelastic lets me control the tear much more easily. I have performed more than 1,000 cases with Healon5, and I have never had a capsulorhexis tear out to the periphery.

Healon5 was designed to offer protection during phacoemulsification. It allows the surgeon to perform a much more posterior phacoemulsification because its dispersive properties separate, allowing it to remain in the AC during the phaco process. I had to modify my technique slightly to allow for a more posterior phaco procedure, but I feel that the protection and surgical outcomes of the posterior procedure far outweigh having to adopt a new technique (Figure 3).

Some surgeons use an array of viscoelastics depending on the type of case, but I do not recommend this with Healon5. Because it requires a learning curve, I feel that it is better to become comfortable using Healon5 rather than reserving its protective qualities for only difficult cases. I recommend that surgeons use Healon5 in the majority of their cataract cases. The only time I deviate from Healon5 is in my transplant cases, in which I use Viscoat instead. I often leave Viscoat in the eye at the end of the transplant case without incurring significant IOP problems.

I make sure to remove Healon5 completely at the end of each case. After IOL insertion, when the lens is off-center, I extract the Healon5 from behind the IOL and then move into the anterior chamber to complete its removal. My IOP spikes are now lower compared to my cases prior to using Healon5, when in the past, I occasionally did not remove all the viscoelastic from the eye. Finally, I never worry about running out of Healon5 during a case; although some viscoelastic may be lost from the AC, I have never had to open a second vial.

Selecting For The Situation

Douglas K. Grayson, MD
The viscoelastic I choose for standard cataract extraction cases is Ocucoat (Bausch & Lomb, Rochester, NY). Ocucoat is a particularly ideal agent to use in conjunction with my phaco-tilt technique, which allows efficient nucleus removal for all grades of cataract.1 Ocucoat is available in 1-mL dosages, which provides ample volume to lubricate the lens injector cartridge, coat the anterior cornea for improved intraocular visualization, and to complete cataract extraction and IOL implantation—all at an economical price. In addition, Ocucoat does not require refrigeration, thereby simplifying storage requirements.

Ocucoat provides endothelial cell protection on par with any other dispersive viscoelastic on the market today. Interestingly, while the adhesive property of Viscoat is often cited as synonymous with superior cell protection, it is well known that it requires aggressive irrigation and aspiration for adequate removal. Such prolonged flow in the chamber offsets Viscoat's potential adhesive benefits. In contrast, Ocucoat is easily removed at the conclusion of the case. In a recent randomized, prospective clinical study conducted by Holzer et al, Ocucoat provided similar endothelial cell protection to Viscoat.2

Amvisc Plus (Bausch & Lomb) is also an excellent choice for today's extraction and lens implantation techniques. This viscoelastic provides an ideal balance of both cohesive and dispersive properties. Its molecular weight (approximately 1.5 M daltons) makes it moderately cohesive. Importantly, George Beiko, MD, presented results of a randomized, prospective clinical study in which there was no significant difference in endothelial cell protection between Healon5 and Amvisc Plus.3 In complicated or challenging cases that will require more time and present less margin of error, I employ a dual viscoelastic strategy using a combination of Ocucoat and Amvisc Plus, similar to the soft-shell technique of Steven Arshinoff, MD. I have described this technique in a case with a very shallow chamber and very small pupil.1

Steven H. Dewey, MD, practices in Colorado Springs and is an Associate Clinical Professor at the University of Colorado. He does not hold a financial interest in any of the products mentioned herein. Dr. Dewey may be reached at (719) 475-7700; deweys@prodigy.net
Satish Modi, MD, practices in Poughkeepsie and Fishkill, New York. He also serves as an Assistant Clinical Professor of Ophthalmology at the Albert Einstein College of Medicine, in the Bronx, New York. Dr. Modi is on the Speakers Bureau of Alcon Surgical. He may be reached at (914) 997-2222.
Douglas A. Katsev, MD, practices at the Laser Eye Care Center the Sansum-Santa Barbara Medical Foundation Clinic in Santa Barbara, California. He does not hold a financial interest in any products mentioned herein. Dr. Katsev may be reached at (805) 681-8950; katsev@aol.com
Douglas K. Grayson, MD, FACS, serves as Medical Director of Omni Eye Services in Iselin, NJ. He does not hold a financial interest in any product mentioned herein. Dr. Grayson may be reached at (201) 368-2444; grayson@omnieyeservices.com
1. Grayson D: Phaco-tilt. Video Journal of Ophthalmology; 2001: Third Quarter
2. Holzer MP, Tetz MR, Auffarth GU, et. al: Effect of Healon5 and four other viscoelastic substances on intraocular pressure and endothelium after cataract surgery. J Cataract Refract Surg 27:213-218, 2001
3. Guttman C: Endothelial protective qualities of OVDs identified: Healon 5, Amvisc Plus appears to protect the anterior chamber during phacoemulsification. Ophthalmology Times, September 1, 2001. Presented by Dr. Beiko at the ASCRS Congress 2001.