Cohesive viscoelastics may be useful for phakic IOLs

Cohesives should be treated as a new surgical tool.

Before insertion of the Artisan (Ophtec) phakic IOL, Miostat is used to bring down the pupil (figure 1). Viscoelastic is injected between the IOL and the cornea to protect the cornea (figure 2). At the end of the procedure, saline solution is injected to remove the cohesive viscoelastic as a single block (figure 3). (Photos courtesy of Camille J.R. Budo, MD.)

Using cohesive viscoelastics can aid removal of the substance after phakic IOL implantation and thus avoid postoperative pressure spikes.

Cohesives offer more advantages than disadvantages in phakic IOL surgery, said Robert D. Fechtner, MD, director of the Glaucoma Service of the University of Medicine and Dentistry in Newark, U.S.A.

“Viscoelastics have to be viewed as a surgical tool, and there are differences among the various viscoelastics that should direct surgeons to select the appropriate tools for the task,” Dr. Fechtner said.

Too little, too much

According to Roberto Zaldivar, MD, of Mendoza, Argentina, past experiences with phakic lenses resulted in severe complications. In the 1980s and early 1990s, viscoelastics trapped between the phakic lens and the iris plane created a mechanical block that impeded free circulation of the aqueous humor to the anterior chamber, Dr. Zaldivar said.

Intraocular pressure (IOP) spikes resulted from inadequate temperature preservation of the viscoelastics during transportation. Some products were withdrawn from the market because once the product’s temperature changed, its use in the eye caused severe corneal edema, glaucoma and iris atrophy.

Today, the biggest problem is a failure to remove all the viscoelastic material. Dr. Zaldivar said that highly cohesive viscoelastic products are more likely to cause IOP increases because of the difficulty of aspirating them thoroughly from small anterior chambers.

“The smaller the space, the easier it is to cause IOP spikes with small amounts of viscoelastic substances,” he said. “This is even more frequent in young patients who are more susceptible to present with IOP spikes.”

According to Camille J.R. Budo, MD, of Melveren, Belgium, leftover viscoelastics can trigger high IOP about 2 to 3 hours after surgery. All the viscoelastic material must be removed at the end of the procedure. Therefore, he recommended a cohesive viscoelastic.

“After the incision of the cornea, some viscoelastic material is injected. The quantity is important. To avoid floating of the IOL in the viscoelastic, we inject a small amount of viscoelastic at this stage. Once the IOL is brought in the anterior chamber, more viscoelastic material is injected between the IOL and the cornea. First to protect the endothelium and, secondly, to create a firm contact between the IOL and the iris. Also the enclavation is facilitated,” Dr. Budo said.

He always places the same viscoelastic material on the conjunctiva around the incision to avoid any contact of the IOL with the conjunctiva during implantation. He limits the volume of viscoelastic to about 0.6 mL. At the end of the procedure, he injects balanced salt solution into the anterior chamber and uses a 25-gauge cannula to remove the cohesive viscoelastic as a single block. Peripheral iridectomy or iridotomy is always performed.

Georges D. Baikoff, MD, of Marseille, France, uses an angle-supported phakic IOL and relies on viscoelastics to deepen the anterior chamber.

He does not use methylcellulose or hyperviscous substances, and prefers to use a 0.8-mm syringe to inject enough of the viscoelastic.

“My concern is to have a deep anterior chamber during the introduction of the lens,” Dr. Baikoff said. “If the anterior chamber flattens, I would stop the maneuvers and refill the anterior chamber with viscoelastic.”

At the end of the procedure, he seeks to remove the viscoelastic and reduce the risk of hypertonia, which can cause ischemia of the iris with mydriasis and an atonic pupil.

He does not routinely deliver glaucoma medications, but will vary that practice if he is visiting another clinic. Then, he gives intravenous acetazolamide immediately postoperatively to control IOP.

A new tool

In Argentina, Dr. Zaldivar said he uses methylcellulose while injecting, folding and placing phakic IOLs. He described it as the key to success in young phakic patients with small anterior chambers, because the substance is easy to remove.

After injecting the viscoelastic, he carefully inserts the lens or, if needed, retrieves it with irrigation/aspiration tips. He performs laser iridectomies and, if he suspects they are not fully open, also uses surgical iridectomies.

“Correct use of viscoelastic substances associated with routine peripheral iridectomies substantially decreases the risk of IOP increase,” he said. “Performing two laser iridectomies preoperatively and using methylcellulose hardly ever provokes high IOP. So the best way to manage this event is preventing its occurrence.”

He clears the viscoelastic from the chamber by injecting balanced salt solution into the anterior chamber and letting it flow out freely but slowly. He maintains the anterior chamber with the balanced salt solution. “In young patients with positive IOP, this maneuver is critical, and a suture should be placed in the incision before cleaning the viscoelastic to avoid the collapse,” he said.

Careful procedure

All viscoelastics protect the endothelium, since no phaco energy is involved and bits of nucleus are not moving about the eye, Dr. Fechtner said. So cohesive viscoelastics are more easily removed from the eye.

Carefully removing the viscoelastic at the end of the case is the best way to prevent pressure spikes. This can be done easily with older and cheaper irrigation and aspiration equipment, Dr. Fechtner said. It is not necessary to use expensive phaco tubing and instruments.

“Any eye that has a paracentesis can readily have some viscoelastic removed, with an immediate reduction in IOP,” he said. “A paracentesis always offers a safety valve.”

Most phakic IOL procedures are done in young, healthy eyes that can withstand transient IOP elevations, Dr. Fechtner said. However, episodes of elevated IOP could be compared with an attack of angle closure. The sudden high pressure can cause substantial optic nerve injury over a relatively short time period. Also, vascular occlusive events can have catastrophic effects on vision.

Prevention is the key and recognition of treatment if the pressure spike should occur, Dr. Fechtner said.

“Patients who have pressure spikes are symptomatic,” he said. “They will have pain, headaches and perhaps nausea. They are sick and know something is wrong.”

Patients should be given instructions, that is, if they have pain, headaches, nausea then they need to contact the surgeon and they should be seen immediately.

“That’s probably one of the best preventive measures,” he said. “I would be reluctant to advise that every patient that has this procedure have their pressure checked at 8 hours, although in the practice setting where that is possible, that would certainly be a very conservative and effective measure for detecting these spikes early.”

For Your Information:

Camille J.R. Budo, MD, can be reached at Sint-Godfriedstraat 8, Sint-Truiden, Melveren 3800 Belgium; +(32) 11-689-684; fax: +(32) 11-688-286. Dr. Zaldivar has no direct financial interest in any of the products mentioned in this article. However, he is a paid consultant for Ophtec.

Georges D. Baikoff, MD, can be reached at the Clinique Monticelli, 88 Rue Cdt Rolland, Marseille 13008 France; +(33) 49-116-2228; fax: +(33) 49-116-2225. Dr. Baikoff has a direct financial interest in the phakic IOL. He is a paid consultant for Bausch & Lomb and CIBA Vision.

Robert D. Fechtner, MD, can be reached at the University of Medicine and Dentistry of New Jersey, Department of Ophthalmology, 90 Bergen St., 6th Floor, Newark, NJ 07103-2499 U.S.A.; +(1) 973-972-2030; fax: +(1) 973-972-1194.

Roberto Zaldivar, MD, can be reached at the Instituto Zaldivar, Av. Emilio Civit 685, 5500 Mendoza, Argentina; +(54) 261-4293222; fax: +(54) 261-4380350. Dr. Zaldivar has no direct financial interest in any of the products mentioned in this article, nor is he a paid consultant for any companies mentioned.