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Viscocanalostomy plays important role among modern glaucoma surgical options

Presentations at this year’s Congress of German Ophthalmic Surgeons covered subjects from viscocanalostomy to microplasmin treatments.

ByJared Schultz

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NUREMBERG – Restoring the flow of aqueous into Schlemm’s canal has been a successful approach to lowering IOP over the long term in glaucoma patients, Robert Stegmann, MD, told attendees here at the Congress of German Ophthalmic Surgeons.

Dr. Stegmann, the developer of viscocanalostomy, spoke about his results with the technique in South Africa during a seminar on its role in the modern treatment of glaucoma.

Other speakers praised Dr. Stegmann for making the journey from South Africa to share his views on the technique he created 12 years ago and has been teaching ever since.

He said the technique is based on finding blocked outflow channels in the trabecular meshwork and opening up those flow channels into Schlemm’s canal. The technique was developed as an alternative to trabeculectomy.

Robert Stegmann

“One such channel could completely control even the worst case of glaucoma if you could harness that one,” he said. He showed a video of eyes being injected with saline solution. Differences that could be seen between normal eyes and glaucomatous eyes illustrated the importance of opening the ocular channels, Dr. Stegmann said.

“Pathology as well as anatomy has tremendous variation in these cases,” he said.

According to Dr. Stegmann, the incidence of glaucoma in African patients is the highest in the world. He is accustomed to treating patients as young as 14 years old.

“At that age, glaucoma is a surgical disease, not a medical disease,” he said.

A common factor in cases he has examined is a collapse of Schlemm’s canal, he said, resulting in low aqueous flow because of “patchy filling” of the canal.

“That is the worst sign of pre-glaucoma,” he said.

Techniques decrease IOP

Viscocanalostomy and phaco-viscocanalostomy both safely and effectively decrease patient IOP, according to Clive Peckar, MD, of the Warrington Hospital, United Kingdom.

Dr. Peckar said he performed viscocanalostomy on 34 patients and phaco-viscocanalostomy on 76 patients, with a mean follow-up of 7.5 years for both groups.

Preoperatively, the viscocanalostomy patients had a mean IOP of 37 mm Hg, and the phaco-viscocanalostomy patients had a mean IOP of 33 mm Hg, he said.

Postoperatively, IOP fell to 17 mm Hg in the viscocanalostomy patients and 16 mm Hg in the phacoviscocanalostomy patients, he said.

“Viscocanalostomy is a safe and effective surgical procedure for the prevention of chronic glaucoma, and phaco-visco is a safe and effective surgical procedure for the prevention of cataract in association with glaucoma,” he said.

If performing phacoemulsification with viscocanalostomy, Dr. Peckar noted that phaco should be done after opening Schlemm’s canal but before creating Descemet’s window and removing the juxtacanalicular endothelial cell layer.

Dr. Peckar described himself as a student of Dr. Stegmann. He learned the technique from Dr. Stegmann in 1997 as an alternative to bleb-dependent surgical techniques, which are known to have high failure rates.

Innovations in posterior segment

Recent developments in the treatment of retinal diseases offer encouragement that these historically difficult-to-treat conditions may some day be more effectively managed, said August F. Deutman, MD, PhD.

Dr. Deutman outlined recent developments in ophthalmology in his presentation of the Ridley Lecture. He paid particular attention to advances in treating posterior segment diseases such as age-related macular degeneration.

“Vitreoretinal surgery is something I have studied in detail,” he said.

Before describing recent advances, he acknowledged the earlier work of such innovators as Paul Cibis and John Scott, who developed applications for silicone oil in vitreoretinal surgery.

Dr. Deutman urged the audience not to become disappointed because of how difficult posterior segment diseases are to treat. He noted that recently developed anti-VEGF therapies have made significant inroads in the treatment of AMD.

He also focused on Factor H, a gene researchers have discovered has a strong association with AMD.

“It is important to understand the pathogenesis of macular disorders,” he said. “In the next few years, we may find new therapies that will help treat AMD superiorly with the knowledge of these genetic defects.”

He also discussed recent findings that asymptomatic fellow eyes in patients with a macular hole often show changes on ocular coherence tomography despite the lack of symptoms.

Dr. Deutman outlined new developments in stem cell therapy, gene therapy and passive release drug delivery. Research such as this, he said, is building new enthusiasm in the field.

“Of course, nutrition is still important no matter what the medical companies may tell you,” he noted.

Corneal herpes management

Prevention of recurrence of herpes simplex virus (HSV) keratitis is thought of “much too rarely,” one physician said during an update on the management of the disease during the conference.

Ophthalmologists have a wealth of information about how to treat HSV keratitis, said Thomas Reinhard, MD, of the University of Freiburg, but they should spend more time thinking about how to prevent its recurrence.

For patients who have a high risk of recurrence of HSV keratitis, Dr. Reinhard recommended attempting long-term prevention by treating with 400 mg of acyclovir “two or three times daily for 2 or 3 years.”

Recurrence of HSV keratitis is often seen after penetrating keratoplasty in herpetic eyes, Dr. Reinhard said.

“Immune reaction and herpes recurrence in the first few years occurs in many patients,” he said.

As a preventive measure when PK is performed, surgeons can take a flap of conjunctival tissue from the surrounding area and graft it onto the diseased area, Dr. Reinhard suggested.

Acyclovir should be the first-line therapy, he said. Other antiviral medical treatments include brivudin, trifluridine and gancyclovir.

“We have very potent local and systemic antiviral drugs, particularly for HSV patients,” Dr. Reinhard said. He cautioned physicians about the use of steroids in susceptible patients.

Randomized trial for CRVO

A multicenter clinical study of two treatments for central retinal vein occlusion (CRVO) has been initiated in Europe, one speaker said.

The trial, which is to enroll 240 patients at 22 centers in Europe and elsewhere, will compare the use of radial optic neurotomy and intravitreal triamcinolone injection for the treatment of CRVO, said Susanne Binder, MD. She described the trial as the first multinational effort to compare the efficacy of the two treatments.

“Radial optic neurotomy and triamcinolone are used frequently and often in an uncontrolled fashion in small studies [to treat CRVO],” Dr. Binder said. “We need a randomized trial.”

The patients will be followed for 12 months. The primary endpoint, she said, will be best corrected visual acuity 1 year after treatment. The participants’ vascular changes will also be studied.

One group of patients in the trial will be given a 4-mg dose of intravitreal triamcinolone, Dr. Binder said, and another will undergo radial optic neurotomy.

Patients with CRVO who are included in the study will have nonperfusion of more than 10 disc diameters.

Dr. Binder said a similar single- center study of 30 patients at her university in Vienna is looking at choroidal blood flow preoperatively and postoperatively, as well as retrobulbar blood flow velocity and IOP.

“The pathogenesis of venous occlusion is still the subject of controversial discussion,” Dr. Binder said. “It will be the end of the study that will demonstrate to what extent we can achieve our goal with radial optic neurotomy.”

Corneal surgeon honored

Corneal surgeon Ali Khodadoust, MD, who implanted the first AlphaCor artificial cornea in a human, was honored at the congress.

Delivering the Innovator’s Lecture, Dr. Khodadoust compared the human body to a universe and the eye to a window between the internal and external universes.

“Ophthalmologists are guardians of this window. Their contribution to the life of mankind is priceless,” he said.

Dr. Khodadoust, a clinical professor at Yale University, became the first surgeon to implant the AlphaCor artificial cornea in 2004. The device, developed by Argus Biomedical, is distributed in the United States by CooperVision Surgical.

The development of an artificial cornea was significant because it eliminated the need for immunosuppression therapy as is required with human tissue transplants, he said.

“We are getting deeply involved in high-tech technology, but we never had the chance to sit down and think of the quality and contribution that we have been able to provide to mankind during our lifetime,” he said.

Silicone IOL design

The introduction of sharp-edged designs for silicone IOLs has helped to reduce the incidence of posterior capsular opacification associated with the lenses, according to one surgeon.

“No other lens has benefited quite so much from sharp-edged IOL designs,” said Rupert Menapace, MD. Criticism of silicone IOLs dates from the time when they featured rounded edges and a higher incidence of fibrosis and PCO than other materials, he added.

“In the case of the modern silicone IOLs, we no longer have peripheral posterior capsular fibrosis because the migration of anterior epithelial cells is hampered,” he said.

Dr. Menapace presented 3-year follow-up data from a prospective randomized study in which patients received either an Advanced Medical Optics CeeOn silicone IOL or an Alcon AcrySof acrylic IOL. After 3 years, there was no significant difference between the two lenses in 53 eyes, he said.

“The silicone lens does tend to yield better results,” he added. “My conclusions concerning post-cataract performance, biocompatibility and biostability is that silicone is outstanding.”

Study of microplasmin enzyme

An enzyme that may improve the success of vitrectomy surgery is undergoing pre-clinical testing, Anselm Kampik, MD, told attendees.

He said the enzyme, called microplasmin, is currently undergoing tests to determine the most effective dose and timing for its use.

“We expect that 1 year from now we will have a dose-ranging curve, and then we can do clinical tests,” Dr. Kampik said.

According to Dr. Kampik, microplasmin induces vitreous detachment in a dose-dependent fashion.

“Complete vitreoretinal separation is possible without any damage to the retina,” he said.

Earlier iterations of the enzyme plasmin had been successful in separating the vitreous but not at the vitreous base, he said.