Expert: Surgery can benefit end-stage glaucoma patients

Elie Dahan

A transient postoperative hypertensive phase is normal, and surgeons should refrain from administering topical IOP-lowering medications during this phase.

Surgeons should think more positively about surgery in end-stage glaucoma patients and not let myths and misconceptions about the risks of glaucoma surgery mislead them to wrong conclusions, according to Elie Dahan, MD, MMed (Ophth), speaking at the World Glaucoma Congress in Paris.

“The first big myth is the so-called ‘wipeout phenomenon’ — ie, the sudden loss of vision that is supposed to occur in end-stage glaucoma patients postoperatively,” he said.

Citing studies by Moster and Moster, Topuzis, Lee, and Simon, Dr. Dahan said that the wipeout phenomenon is not a real risk but a myth that has been exaggerated.

In the recent literature, the wipeout phenomenon rate ranges from 0% to 7%, but the myth persists because surgeons fear operating on patients with very low residual vision who often have unrealistic expectations about the outcome of glaucoma surgery, he said.

Surgeons should not fear the transient relative visual acuity loss that might occur in the immediate postoperative period for reasons including macular edema due to hypotony, hyphema, shallow anterior chamber or viscoelastic in the anterior chamber, Dr. Dahan said.

“These are temporary conditions that generally resolve spontaneously,” he said.

Preferred procedure

According to Dr. Dahan, the procedure of choice for end-stage glaucoma is nonpenetrating glaucoma surgery, either deep sclerectomy or viscocanalostomy, because of the low complication rate. However, nonpenetrating glaucoma surgery requires a long learning curve in normal conditions and even more so when dealing with end-stage glaucoma patients.

“You need to perform at least 200 successful nonpenetrating glaucoma procedures in order to achieve an acceptable level of proficiency,” he said. “In the same way, you would not want a challenging cataract case to be performed by someone who has done less than 200 [phacoemulsification] procedures.”

His second-choice procedure for end-stage glaucoma is the Ex-PRESS mini shunt (Alcon).

“It is safer than trabeculectomy, but you need to have done at least 50 successful cases before you [can] use it in end-stage glaucoma,” he said.

Transforming growth factor concentration

An important misconception on the risks of glaucoma surgery concerns the management of the postoperative hypertensive phase that often occurs from the second week onward. A transient hypertensive phase might occur after any glaucoma surgery. It has typically been reported after the use of silicone tube implants but also occurs after trabeculectomy, nonpenetrating glaucoma surgery and Ex-PRESS mini shunt implantation. The cause for the hypertensive phase is a high concentration of transforming growth factors in the aqueous after surgery.

“[Transforming growth factors] are responsible for healing and scar formation. The concentration is initially high, causing excessive temporary scarring around the filtration site. As the concentration returns to normal levels after 2 to 3 weeks, the IOP also returns to normal levels when inflammation and scarification resolve,” Dr. Dahan said.

During this phase, surgeons should refrain from administering topical IOP-lowering medications or manipulating the site of filtration.

“Just do a gonioscopy to view the filtration site and see what’s happening. Do not massage and do not teach the patient to massage, because massage is a coarse, inaccurate, uncontrolled and potentially dangerous act. If you massage after nonpenetrating glaucoma surgery, the risk is that you’ll rupture the trabeculo-descemetic membrane and cause iris incarceration,” Dr. Dahan said.

Topical IOP-lowering medications, which contain preservatives, have a toxic effect on the healing conjunctiva and jeopardize healthy bleb formation.

“By giving anti-glaucoma medications postoperatively, you reduce the flow through the filtration site and accelerate conjunctival scarring. It’s like shooting yourself in the foot,” Dr. Dahan said.

Suture lysis, needling and YAG laser goniopuncture are the preferred approach for many surgeons when IOP rises, but these interventions are mostly unnecessary because of the transient nature of the hypertensive phase, according to Dr. Dahan. Instead, when IOP rises dangerously, an anterior chamber decompression can be performed at the slit lamp through a pre-existing paracentesis.

“In most cases, however, the best thing to do is to sit on your hands and wait,” Dr. Dahan said. “Do not panic, replace the steroids with nonpreserved nonsteroidal anti-inflammatory drugs to reduce the steroid response, and allow the IOP to rise to the low 20s without intervening. A moderate IOP rise, within this range, is in fact beneficial, especially in nonpenetrating glaucoma surgery, as it stretches the trabeculo-descemetic window and improves filtration.”

IOP usually settles back to normal levels within 2 to 3 weeks. If it remains high after 3 months, surgical revision of the filtration site with additional application of mitomycin C under the scleral flap should be considered rather than reverting to anti-glaucoma medications, Dr. Dahan said.

Another misconception about IOP control in patients with end-stage glaucoma concerns the use of multiple medications. According to Dr. Dahan, giving four different medications to control IOP at this stage is neither safe nor realistic. Vision and visual field loss progress despite the low IOP achieved by the use of multiple medications. The so-called wipeout phenomenon can occur in end-stage glaucoma seemingly controlled by multiple glaucoma medications.

“The reports on the success rate in glaucoma surgery are often misleading because of the lax definitions and nonstandardized criteria used by different authors. What we should aim at is complete success without medications and not partial success with medications. And we should aim at no more than 18 mm Hg and not 21 mm Hg as the maximal IOP value. In fact, end-stage glaucoma patients need complete success with IOP less than 15 mm Hg,” Dr. Dahan said. – by Michela Cimberle

Reference:

• Moster MR, Moster ML. Wipe-out: a complication of glaucoma surgery or just a blast from the past? Am J Ophthalmol. 2005;140(4):705-706.

• Elie Dahan, MD, MMed (Ophth), can be reached at Ein Tal Eye Center, 17 Brandeis St., Tel Aviv 62001, Israel; +97235433222; fax: +97235441222; email: elie.dahan@gmail.com.
• Disclosure: Dr. Dahan is a consultant for Alcon.

Philippe Sourdille

Very few recent literature reports deal with surgical results in end-stage glaucoma patients, and there is certainly a need for contemporary work. The author has a wide, long-term experience and a comprehensive approach to glaucoma treatment. His recommendation to prefer nonpenetrating surgery is based on a related lower complication rate as compared with all other techniques.

End-stage glaucoma patients generally present with cumulative poor prognosis factors: severe ocular surface disorders, previous surgeries, decreased aqueous production and blood pressure instability. These elements should be treated preoperatively. Associated lens changes, especially in shallow angle eyes, should be considered for combined surgery to associate functional improvement and IOP lowering.

Surgery for end-stage glaucoma should be revisited, based on a comprehensive approach of general and ocular risk factors. Recent or new nonpreserved topical treatments in both preoperative and postoperative stages, high surgical skill and further research on combined wound healing modulation are factors for a better prognosis.

— Philippe Sourdille, MD
OSN Europe Edition Editorial Board Member