Research published in the American Journal of Ophthalmology explored the potential risk factors of Microshunt surgery failure in glaucoma patients via a multicenter retrospective cohort study.
Give me some background first.
Trabeculectomy has been the preferred choice for surgical intervention in glaucoma that’s unresponsive to medical treatment. Over time, though, technology has advanced other safer alternative techniques.
Enter: the PRESERFLO Microshunt (Glaukos), a surgical intervention designed to manage glaucoma that is unresponsive to medical treatments.
However, as glaucoma may vary widely from case to case, there is no single procedure that works best for all glaucoma patients, and techniques can often fail
And the reason for that failure?
Previous research has identified non-White ethnicity, low intraoperative mitomycin C (MMC) levels, and concomitant cataract surgery as risk factors for failure, though there is not enough research to fully understand the causes of Microshunt failure.
And this study?
Investigators sought to determine the risks for the potential failure of a Microshunt in a real-world cohort of glaucoma patients.
So who was included in the study?
Investigators identified 220 eyes (of 220 glaucoma patients) from six glaucoma units who underwent Microshunt implantation between 2019 and 2023.
The mean baseline age was 66.5 years and 95% of patients were White.
How about the criteria for success?
Four intraocular pressure (IOP) success criteria were identified:
- IOP ≤21mmHg with ≥20% IOP reduction from baseline
- IOP ≤18mmHg with ≥20% IOP reduction from baseline
- IOP ≤15mmHg with ≥25% IOP reduction from baseline
- IOP ≤12mmHg with ≥30% IOP reduction from baseline
The term “overall success’ was achieved when all criteria was met with or without the use of anti-glaucoma medications. The term “complete success” was reached when criteria was met without anti-glaucoma medications.
And for failure?
The failure criteria included the following:
- IOP did not meet criteria in two consecutive visits at least 1 month apart and over 6 weeks post-operation
- Systemic acetazolamide use for over 6 weeks post-surgery
- Further glaucoma surgery
- Microshunt revision or removal
- Loss of light perception
- Serious hypotony complications
- Sight-threatening postoperative complications
Findings?
A higher intraoperative concentration of MMC was associated with a reduced risk of microshunt failure.
Tell me more.
Additional risk factors for failure included:
- Pseudoexfoliation glaucoma/pigmentary glaucoma
- Primary angle closure glaucoma (POAG
- Previous non-glaucomatous ocular surgeries
Risk factors affecting overall success included:
- Lower preoperative IOP
- Higher number of preoperative antiglaucoma agents
- Microshunt combined with cataract surgery
Expert opinion?
This research suggests that Microshunt surgery may present positive outcomes for stable visual acuity (VA) and a reduction of IOP and medication usage.
The study authors also emphasized “the importance of high intraoperative MMC dose and careful patient selection” when using Microshunt implantation.
Limitations?
Long-term outcomes of the Microshunt were unable to be determined, as this intervention is fairly new and the follow-up period for participants was relatively short.
Further, the majority of participants were of European descent, so the findings may not be accurately applicable to other ethnic groups.
Finally, the structural and functional outcomes of Microshunt surgery were primarily measured through IOP levels; these did not demonstrate the exact effects of Microshunt on structural and functional progress.
Take home.
Microshunt implantation has been demonstrated to be effective in improving the conditions of glaucoma patients. However, further research must be done regarding the long-term outcomes of Microshunt surgery.