Ex-PRESS success for pressure lowering in glaucoma

New study examines shunt’s effectiveness

Illustration of Ex-PRESS miniature glaucoma shunt insertion
Source: Optonol Ltd.

When it comes to lowering pressure either alone or when combined with cataract surgery, the Ex-PRESS implant (Optonol, Kansas City, Kan.) is an effective option, according to results of a study published in the August 2009 issue of the Journal of Glaucoma.
Investigators were encouraged to do the study by the good results they were getting with the device, said Elliott M. Kanner, M.D., Ph.D., assistant professor of ophthalmology, Hamilton Eye Center, University of Tennessee Health Science Center, Memphis, Tenn. “We feel that it is a superior operation, and we have done a lot of them,” he said. “This is the largest series of Ex-PRESS operations that has been followed for the longest time.”
Dr. Kanner felt that it was a good opportunity to share the wealth of knowledge with other clinicians. “We found some complications that are easily dealt with that have not been described before,” he said. “Since we’ve done a lot of these operations, I thought it would be helpful to share our experiences so people know how the surgery works.”

Extensive series

Included in the retrospective, comparative case series were 345 eyes, with 231 receiving the Ex-PRESS implant under the sclera flap alone and 114 eyes receiving the device in the same way but in combination with phacoemulsification. Patients were followed for up to 46 months.
Results with the device were promising. “There is success with this device either with or without concurrent phacoemulsification surgery,” Dr. Kanner said. “We had consistent lowering of pressure with few complications.”
One complication that they were called upon to deal with involved occasional tube blockages. Investigators found that these were easily handled. “We used the Nd:YAG laser to clear the occasional blockage that we saw in the tube,” Dr. Kanner said. “We’d have high pressure with a low bleb and it didn’t respond to laser suture lysis. We would see a slight deposit on the tip of the tube and we found that if we used the Nd:YAG laser, we often got flow immediately.”
Another complication experienced with the Ex-PRESS shunt was hypotony. This was found in one case after completion of the study. “Usually it doesn’t require intervention, which is a real benefit of the device,” Dr. Kanner said. “Even with a low pressure, patients don’t have a completely flat chamber and they don’t have kissing choroidals, so we leave them alone and they recover naturally.”
In addition, in a few cases there were device erosions. “In a big enough study this is to be expected and was nowhere near the rate that was seen when the device was not under a sclera flap,” Dr. Kanner said.

Ex-PRESS advantages

The surgery for implanting the device is not that different from trabeculectomy. “It’s similar to a standard surgery except that we’re not doing a sclerotomy,” Dr. Kanner said. “In general I would omit using viscoelastic—we didn’t use viscoelastic in probably 80% of cases.” Dr. Kanner found that the chamber is stable through the entire surgery so viscoelastic is probably not needed. This offers an advantage to glaucoma patients. “This means that the first day post-operatively, pressure is real pressure,” Dr. Kanner said. “It is not pressure that has been clouded by what the viscoelastic is doing.”
There is another advantage Dr. Kanner found to doing the procedure without viscoelastic. “In cases where the pressure is in the high or mid teens we have the option of cutting a stitch that early, which is not advisable in a standard trabeculectomy,” he said.
Dr. Kanner hopes that practitioners will come away from the study with the understanding that use of the Ex-PRESS shunt is a modification of the gold standard trabeculectomy procedure, with good results. “It does decrease the early complications, and as far as we can tell, it doesn’t seem to have any increased long-term complications or limitations that are different from trabeculectomy,” he said.
There is some anecdotal evidence that there can be erosion in some cases. “We had erosion in a rheumatoid arthritis patient and in a patient who was undergoing chemotherapy,” Dr. Kanner said. “Anyone who has a tissue problem may do better without an implanted device.”
Overall, however, for the majority of patients, Dr. Kanner finds that this is his filtering procedure of choice. “Unless there is a good reason not to do it, we generally do this as a filtering surgery,” he said. “I use it in my practice as a replacement for standard trabeculectomy.”

Editors’ note: Dr. Kanner has no financial interests related to his comments.

Contact information

Kanner: 901-288-5340, emkanner@gmail.com