Glaucoma
July 2021
by Liz Hillman
Editorial Co-Director
Infection is a risk for any ocular surgery, but in general, Constance Okeke, MD, thinks there are a few reasons why there isn’t a lot of discussion about infection when it comes to glaucoma procedures. MIGS, which have become increasingly common, have a lower infection risk profile compared to incisional glaucoma surgery. In addition, traditional glaucoma surgery (tubes or trabs) now have enhanced techniques that may reduce infection risk even in these procedures.
“I don’t see a lot of infection in surgery that I do in glaucoma,” Dr. Okeke said. “I do think it has a lot to do with the reduction of trabeculectomies that I have done over the course of the last decade and the increase in MIGS procedures, either standalone or combined with cataract surgery. I do not see incidence of infection in any way increased, but decreased.”
Source: Kateki Vinod, MD
Infection and MIGS
Dr. Okeke said there is a paucity of literature evaluating infection rates with MIGS procedures, but she thinks the rate is low in her clinical experience. She compared the rate as likely similar to that of endophthalmitis in cataract surgery, which she put between 0.13–0.7%.
“I have not seen any increase in rates of infection with my cataract surgeries because the majority of my surgeries are combined [with MIGS], and I’ve had rare instances of endophthalmitis in my surgical cases. I think the infection rates for MIGS procedures are likely similar to cataract surgery.”
Another change that could be impacting infection rates for the better is intracameral antibiotics. Dr. Okeke said she began using intracameral antibiotics with her standalone MIGS and combined cataract surgery procedures within the last 4–5 years.
If an infection did occur after a procedure that included MIGS, she said it is handled in the same way it would be if it had occurred after cataract surgery alone.
“I have never had an experience where a patient had endophthalmitis and it was needed to remove a device or stent. … Just like with cataract surgery, the implant stays in the eye, but you treat the infection,” Dr. Okeke said.
Infection and incisional glaucoma surgery
While MIGS avoids some of the complications associated with incisional glaucoma surgery, tube shunt and trabeculectomy procedures are still a mainstay for glaucoma patients who need dramatic pressure lowering. They also carry a higher risk for infection.
Kateki Vinod, MD, explained that trabeculectomy, tube shunts, and the XEN Gel Stent (Allergan), which has been described as MIGS plus and is still bleb-forming, cause disruptions in conjunctival integrity, which can present pathways for pathogens to enter the eye, even years after surgery. She noted that while endophthalmitis rates associated with these filtering surgeries are low, they tend to be higher than infections post-cataract surgery. One study based on 5-year, retrospective data saw a 0.55% risk of blebitis and 0.45–1.3% risk of endophthalmitis after glaucoma filtering surgery.1
The risk of infection in a bleb-forming procedure is lifelong and thus patients require extensive counseling preop for the symptoms to look out for, Dr. Vinod said.
Dr. Vinod said most surgeons prescribe topical, broad spectrum antibiotics for 1 week postop, and there has been increased interest in intracameral antibiotics during glaucoma filtering procedures. Just this year, a study of cases from Aravind Eye Hospital showed a four-fold lower rate of endophthalmitis in patients who received intracameral moxifloxacin during trabeculectomy or trab combined with phaco.2
With tube shunts, she said they are being positioned to maximize eyelid coverage (around the 12 o’clock position for superotemporal implants and 6 o’clock for inferonasal implants) and minimize macrotrauma from eyelid rubbing that could lead to conjunctival erosion.
“Also, we have graft materials that are maybe better to cover the tube,” Dr. Okeke said. “You can also sometimes have erosion of the conjunctiva, but if you have corneal graft material and you put the epithelium on the outside, that can sustain exposure to the atmosphere and not necessarily erode. … The epithelium can maintain stability.”
Dr. Vinod noted the importance of a watertight conjunctival closure for these procedures to avoid early-onset wound leak that could serve as a conduit for pathogens.
“In the same vein, I always suture my clear corneal main wound when performing cataract surgery in combination with incisional glaucoma surgery, even if the wound already appears to be watertight, as lower postoperative IOPs can increase the risk of wound leak,” she said.
Both Drs. Vinod and Okeke emphasized the importance of inspecting the bleb or tube at each visit with the patient for leak or erosion, respectively. Both are opportunities for infection to occur and should be addressed promptly with surgical revision.
“When intraocular infections do occur, they must be recognized and treated immediately and aggressively to optimize visual outcomes,” Dr. Vinod said.
In cases of blebitis, she advised taking a culture from the bleb when possible to better identify the causative organism and beginning treatment with topical broad spectrum (usually fortified) antibiotics right away.
“Although consensus guidelines are lacking, we have a low threshold for performing early vitrectomy with intraoperative intravitreal injection of antibiotics in cases of bleb-related endophthalmitis since the causative organisms tend to be more virulent than those associated with endophthalmitis following cataract surgery,” Dr. Vinod said. “Similarly, no consensus exists regarding the management of tube shunt-related endophthalmitis, including the role of vitrectomy. Some surgeons prefer to remove the tube shunt in eyes with endophthalmitis due to concerns for the growth of a bacterial biofilm within the implant.”
A study based on a literature review published in the journal Eye compared outcomes of explantation of glaucoma drainage devices (GDD) with device retention and compared the outcomes of pars plana vitrectomy vs. antibiotics alone in patients who had endophthalmitis. Ultimately, the authors found that explantation of the devices and immediate vitrectomy were “both associated with better anatomical outcomes in GDD-related endophthalmitis.”3
Dr. Okeke said how blebs are created has also changed over the last 10 years and could be improving infection stats as well.
“We tend to make them more diffuse, and as a result the blebs tend to be less elevated and less ischemic; this can help reduce the risk of bleb leaks in the future,” she said.
About the physicians
Constance Okeke, MD
Assistant Professor
Eastern Virginia Medical School
Norfolk, Virginia
Kateki Vinod, MD
Assistant Professor of Ophthalmology
Icahn School of Medicine at Mount Sinai
New York Eye and Ear Infirmary of Mount Sinai
New York, New York
References
- Vaziri K, et al. Incidence of bleb-associated endophthalmitis in the United States. Clin Ophthalmol. 2015;9:317–322.
- Mitchell W, et al. The effectiveness of intracameral moxifloxacin endophthalmitis prophylaxis for trabeculectomy. Ophthalmol Glaucoma. 2021;4:11–19.
- Islam YFK, et al. Management of endophthalmitis related to glaucoma drainage devices: review of the literature and our experience. Eye (Lond). 2021. Online ahead of print.
Relevant disclosures
Okeke: Allergan, Glaukos, Ivantis, MST, Nova Eye Medical, Santen, Sight Sciences
Vinod: None
Contact
Okeke: cokeke@cvphealth.com
Vinod: kvinod@nyee.edu
