Consider all factors for successful deep sclerectomy

ByJeanne Gonzalez

Careful consideration of preoperative, intraoperative and postoperative factors is necessary for successful deep sclerectomy outcomes, according to one surgeon. In addition to observing wound-healing, having a target pressure and monitoring it closely are important.

Surgical procedure

Careful patient evaluation, surgical precision and close postoperative monitoring are integral for a successful deep sclerectomy outcome. Patients with higher IOP levels, ocular surface integrity and early surgical intervention tend to have a better recovery, according to Philippe Sourdille, MD.

Intraoperatively, injection of antimetabolites, resorbable implants and removal of the juxtacanalicular trabeculum are important. Postoperatively, close monitoring of intraocular pressure is crucial.

To perform deep sclerectomy, Dr. Sourdille creates a superficial scleral flap to act as a cover. He performs a pre-ciliary and pre-descemetic sclerokeratectomy with removal of the juxtacanalicular trabeculum.

“We know from previous studies that the resistance to outflow is mainly located in this area,” Dr. Sourdille said.

He uses wide, resorbable implants and secures them with two sutures. In previous studies, the implants have been biocompatible with eyes. He injects a crosslinked hyaluronic acid implant for the creation of new outflow channels. The purpose is to keep the space, which may aid in preventing inflammation and fibrosis. Dr. Sourdille said the implant is resorbable in 1 to 2+ years.

Philippe Sourdille, MD, at the Clinique Sourdille in Nantes, France, conducted an in-office study to evaluate the results of deep sclerectomy procedures performed there. He reviewed the results of 192 eyes of 118 patients with open-angle glaucoma. The results reflected the initial postoperative outcomes and were identical to those found in the literature. But Dr. Sourdille said it seemed possible to improve those results with a careful initial follow-up.

“The initial work was pure deep sclerectomy with crosslinked hyaluronic acid implant without goniopuncture and without the addition of antimetabolites,” Dr. Sourdille said at the Ocular Surgery News Symposium in Nagoya, Japan, last year. Dr. Sourdille was a guest international speaker at the symposium.

Based on his findings, Dr. Sourdille made modifications to his deep sclerectomy method, which he deemed important in providing a viable alternative to trabeculectomy. After obtaining average results, he said several factors were absent from his technique.

“We did not use goniopuncture nor apply 5-FU [5-fluorouracil] or MMC [mitomycin C] in this initial series,” he said.

Dr. Sourdille said that patients with higher levels of IOP and ocular surface integrity who receive early surgical treatment do better in the long term. Intraoperatively, he aims for an uncomplicated, consistent and complete surgery, and he now includes trabecular dissection and ablation and injects MMC in special indications (reoperations, low-pressure glaucoma and congenital and juvenile glaucoma). He stressed the importance of postoperative IOP observation.

“As for postoperative factors, IOP is extremely important on the first day. It should be low: 4 to 8 mm Hg. If it is not the case, you should question your surgery and look for immediate subconjunctival filtration,” he said. “Intensive monitoring, goniopunctures and wound-healing modulation have proven effective postoperatively. They can be started as early as day 10 to 14.”

This intensive monitoring, if needed, has been associated with better results as compared with previous studies, he said.

Evaluation results

Of the 118 patients (adult and senile open-angle glaucoma), 62% were below 19 mm Hg without medical treatment at 3 years. After 6 years, 50% of patients were controlled without treatment, and 85% of patients had IOP levels below 19 mm Hg with the addition of medical treatment, Dr. Sourdille said. Ten percent of patients needed a second operation with MMC.

Overall, the complication rate was low. When he began the procedure, 10% of patients had trabecular micro-perforations, and 8% had hyphema. Now the perforation rate is below 5%, he said. Part of the reason for the complications was a difficult intraoperative procedure.

“In 4% of the cases, we observed a shallow choroidal detachment, without any flat or shallow anterior chamber,” Dr. Sourdille said.

This increases the risk of developing cataracts, he said.

“The long-term (6-year) rate of cataracts, 12%, enforces the benefits of nonpenetrating surgery compared with the published figures of cataract after trabeculectomy,” he said.

Deep sclerectomy with implant

Now when he performs a deep sclerectomy, Dr. Sourdille uses an implant made of crosslinked hyaluronic acid, which he said is still present after 2 years on ultrasound biomicroscopy examination.

“The implant is highly hydrophilic; it is about 99% water. It is placed in the deepest scleral flap. The superficial flap, which is larger than the deeper flap, is put in place with two posterior sutures. It is not sutured tightly, just enough to allow filtration,” he said.

Previous studies have shown that use of an implant with deep sclerectomy lowers IOP more than deep sclerectomy alone. A study in Rome showed a statistical significance when using the implant, Dr. Sourdille said. With it, patients achieved average IOP levels of 14 mm Hg at 2 years; without it, they achieved average IOP levels up to 18 mm Hg.

“As published by Giorgio Marchini (Verona, Italy), there are three IOP-lowering pathways: the intrascleral penetration, the subconjunctival filtration and uveal resorption. When two of these mechanisms are present, there is a satisfactory IOP result,” Dr. Sourdille said.

Should IOP rise in the early or late postoperative period, he recommended performing goniopuncture, close to Schwalbe’s line but far from the iris root to avoid goniosynechiae. If goniosynechiae are present before or after the gonio-puncture, he said they should be treated immediately with YAG laser on the synechia and argon laser on the base of the iris to prevent recurrence. Administration of subconjunctival antimetabolites may be necessary, he said. This work was conducted in Nantes by Dr. Sourdille’s co-worker Helene Bresson-Dumont, MD, and proved to be efficient, he said.

Prognosis factors

Dr. Sourdille outlined several factors he said were important for a positive outcome. He said toxicity to the conjunctival epithelium by glaucoma medical treatment, especially preservatives, is considered a poor surgical prognosis factor. This medical treatment could also cause multi-drug resistance, he said.

“If MMC fails, it could be due to repeat dosage of the medication that has caused a multi-drug resistance. Cyclosporine could be used before the operation to treat or prevent multi-drug resistance,” he said.

In addition, a careful trabecular dissection is important to remove the juxtacanalicular trabeculum, he said. In a previous study, he showed that trabecular dissection is necessary for optimal aqueous outflow.

“The most frequent intraoperative complication is insufficient dissection. We then have to come back to the sclerocorneal tissue from behind and lift this tissue, creating the pre-Descemetic approach,” he said.

Close postoperative monitoring is also important. Dr. Sourdille said patient IOP should be monitored on the first postoperative day, and subconjunctival filtration should be monitored during the first week. The patient should be monitored frequently throughout the first month. Wound-healing modulation is also important because complications often stem from fibroblastic conjunctiva and sclera, he said.

Future alternatives

Several alternatives are being investigated for more precise surgery and medical treatment, Dr. Sourdille said. Deep sclerectomy by excimer laser is being developed for trabecular dissection, and he said Ehud Assia, MD, is developing a carbon dioxide laser.

In regard to medications, drugs for targeted use, such as anti-TGF-beta, CD95 or anti-metalloproteinase, could succeed better with fewer complications than current 5-FU and MMC, Dr. Sourdille said.

For Your Information:

Philippe Sourdille, MD, can be reached at Le Chaigne, 16120 Touzac, France; +33-630-362-846; e-mail: philippe.sourdille@wanadoo.fr.