June 2020


Ocular Surface Considerations For Surgery
The ocular surface for trabeculectomy and trabeculectomy-like MIGS

by Liz Hillman Editorial Co-Director

Flat neovascularized failed bleb after surgery

Highly inflammatory bleb with mitomycin-C application

Ocular surface disease in a glaucomatous patient
Source (all): Christophe Baudouin, MD, PhD


“Whatever the technique … the bleb remains a concern for the ocular surface, a concern preop, a concern periop, and also a concern postop.”
—Christophe Baudouin, MD, PhD

Optimization of the ocular surface is increasingly a discussion point in the realm of cataract surgery, but the ocular surface impacts the success of many other procedures as well, including glaucoma surgery.
“A good ocular surface is necessary to have a good surgery,” said Christophe Baudouin, MD, PhD, adding that patients on multiple topical treatments for glaucoma (the typical patient scheduled for a traditional trabeculectomy or MIGS-style trabeculectomy) often have a poor ocular surface preoperatively. “If it’s not controlled, they will have a very poor surgery.”
If the ocular surface is already in a pro-inflammatory state before surgery, Dr. Baudouin said it will be more inflammatory afterward, increasing the risk of fibrosis, which could lead to less efficacy of the bleb, bleb failure, and worse IOP control postop.
“As preoperative inflammation underlies postoperative fibrosis and therefore surgical outcome, a better knowledge of ocular surface changes with appropriate evaluation and management should thus become a new paradigm in glaucoma care over the long term,” Dr. Baudouin wrote in a paper published in 2012.1
The first step in achieving this paradigm shift, Dr. Baudouin said, is prevention, removing the compounds responsible for inflammation. This could be preservatives but not always. He said it’s important to realize the compounding effects of preservatives from multiple drops as well as the potential for drug allergies that cause an inflammatory response, such as brimonidine.
Richard Lewis, MD, echoed that brimonidine is a good one to stop a couple of weeks prior to surgery, if possible.
“Their eyes get very irritated, and trying to do a trabeculectomy in that setting is difficult because they tend to bleed more, have more irritation, and are more likely to fibrose,” Dr. Lewis said.
Dr. Lewis mentioned that many drugs that have a mechanism of action based on vasodilation potentially have a similar effect.
Dr. Baudouin’s second step is to treat the ocular surface. This can be done with preservative-free artificial tears, cyclosporine, or a low-dose steroid. Steroids, he noted, can raise intraocular pressure (an especially undesired effect for glaucoma patients), thus he recommended short-term use.
“You need to balance between risk of the steroid and the interest of decreasing inflammation,” he said.
Finally, Dr. Baudouin said his third point is to consider surgery at an earlier stage with, potentially, a less invasive technique.
“For a patient with uncontrolled glaucoma on two eye drops, rather than adding a new drug or changing for a new drug, it’s probably better to go to surgery,” he said, noting laser trabeculoplasty and several MIGS options available. “Propose surgery earlier than an end-stage glaucoma patient with a poor ocular surface.”
Postoperatively, Dr. Lewis said patients take a steroid four times a day for 3–6 weeks. Mitomycin, used intraoperatively, might also be needed postop as well to inhibit fibrosis.
“We’ll take a patient 6–8 weeks postop and in the office use mitomycin in a syringe, inject it near the bleb to try to kill any rapidly dividing cells, and that will slow down the fibrosis or stop it,” he explained.
Dr. Baudouin said he’s very careful with steroids postop, using them for a short period of time (a few weeks) after surgery. He said he might also use a non-steroidal and prescribes preservative-free artificial tears.
“We also have to consider that the bleb is a cause of trauma—stress between the eyelid and the conjunctiva. If the lubrication is not very good, it may also cause discomfort, but again discomfort due to ocular surface disease is not only a question of discomfort but also mechanical stress that can cause inflammatory stress,” he explained.
In some cases, the trabeculectomy procedure can help continue improvement of ocular surface conditions. If the ocular surface was damaged by glaucoma medications and those mediations are stopped due to success of the procedure, the ocular surface improves.
“The question here is to not do surgery too late. If we wait for too long with a very damaged ocular surface, the benefit of surgery and removal of the drug will be limited,” Dr. Baudouin said. “The eye will be damaged with deep, chronic inflammation, fibrosis, and the bleb will not function properly, so it means it might be necessary again to use medication to control pressure after surgery. Prevention and the appropriate time for surgery are important to consider.”
Dr. Lewis noted that sometimes the bleb itself can be irritating postoperatively to the ocular surface, requiring patients to be on artificial tears. It also can be so large it causes disruption in the even tear flow over the cornea, causing dry spots called dellen. This condition, he said, usually goes away on its own if the bleb shrinks.
Considerations for the ocular surface apply to traditional trabeculectomy procedures as well as trabeculectomy-like MIGS, such as the XEN Gel Stent (Allergan) and PRESERFLO (formerly InnFocus Microshunt, Santen), the latter of which is not yet FDA approved.
“Whatever the technique—trabeculectomy, tube in the category of MIGS, whatever—the bleb remains a concern for the ocular surface, a concern preop, a concern periop, and also a concern postop,” Dr. Baudouin said.

About the doctors

Christophe Baudouin, MD, PhD
Professor of ophthalmology
Quinze-Vingts National Eye
Hospital & Vision Institute
Paris, France

Richard Lewis, MD
Sacramento Eye Consultants
Sacramento, California

At a glance

• The ocular surface is a consideration preop, intraop, and postop for trabeculectomy and trabeculectomy-like MIGS.
• An inflamed ocular surface can lead to increased fibrosis and subsequent bleb failure.
• Taking care of the ocular surface preoperatively and postoperatively can prevent some of this fibrosis, enhancing the potential for the procedure’s success.
• Considering less invasive surgical procedures at an earlier stage (rather than when patients might be on multiple drops causing ocular irritation) could have a protective effect for the ocular surface as well.


1. Baudouin C. Ocular surface and external filtration surgery: mutual relationships. Dev Ophthalmol. 2012;50:64–78.

Relevant disclosures

Baudouin: Alcon, Allergan, Aerie Pharmaceuticals, Santen, Thea
Lewis: Aerie Pharmaceuticals, Allergan, Alcon


Baudouin: cbaudouin@15-20.fr
Lewis: rlewiseyemd@yahoo.com

The ocular surface for trabeculectomy and trabeculectomy-like MIGS The ocular surface for trabeculectomy and trabeculectomy-like MIGS
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