Into the category of external MIGS, Dr. Ahmed put the Allergan Xen Gel Stent and the Santen InnFocus MicroShunt, both of which drain through the sclera from the subconjunctival space.
The external MIGS, which create a bleb, have greater probability of hitting target IOP levels without medication; IOP levels with these devices average around 13 mm Hg, said Dr. Ahmed.
The surgeon's choice of procedure depends on the patient's circumstances, Dr. Ahmed said.
"It's very much a matter of balancing out risk reward and effort," he said.
Other factors include the intensity of the postoperative management required, the speed of visual recovery the cost and reimbursement.
The more advanced the glaucoma case, the higher priority becomes the treatment's ability to lower IOP, Dr. Ahmed said. The less advanced the glaucoma, the more important is safety.
"The biggest question I have is whether the patient is controlled at time of presentation," he said.