PreserFlo in Latin America

Main Topics and Key Points:

• Where PreserFlo Fits in the Surgical Toolbox:
  • Dr. Delgado has been using PreserFlo in Colombia since approximately June 2023.
  • He considers it a "wonderful alternative" for glaucoma in slightly older stages than those traditionally addressed by MIGS (mild to moderate glaucoma).
  • It positions itself as a “bridge between the less and the more” on the surgical ladder, specifically between angular MIGS and traditional filtering surgeries (trabeculectomy, valves).
  • It is suitable for patients with moderate to severe glaucoma who have visual field defects, significant optic nerve damage, are uncontrolled on maximal medical therapy, or have failed previous surgeries.
  • The main reason is that, as a bleb-forming surgery, it achieves greater pressure reduction than traditional MIGS, which is necessary for patients with lower target pressures.
• Treatment Algorithm and the Role of PreserFlo:
  • The current algorithm generally starts with medication or SLT (for primary open-angle glaucoma).
  • If this fails, the next step is often MIGS, especially for mild glaucoma where the pressure goal is moderate.
  • However, if the patient has uncontrolled moderate or advanced glaucoma, a traditional MIGS "maybe I don't know that it's not going to give me the appropriate result."
  • In these cases, you can “skip a step or two on that ladder” and choose a more substantial surgery such as PreserFlo, or even go straight to a trabeculectomy or a valve if the demand is even greater.
  • PreserFlo ideally fits after angle-based MIGS (stents or trabecular meshwork excision) but before major filtering surgeries, acting as that “space” or “bridge.”
• Surgical Technique and Considerations:
  • Use of Mitomycin C: Considered mandatory. “The main enemy, without a doubt, is fibrosis.”
  • The first studies with 0.2% had a high failure rate; the switch to 0.4 mg/ml significantly improved the success rate.
  • Although the PreserFlo material is a special polymer that produces less fibrosis (“immunologically inert”), the body still forms fibrosis, and “at the end of the day, if we don't use mitomycin, our failure rate is going to be very high.”
  • Mitomycin C should be applied posteriorly, as the device filters further behind the limbus (approximately 6 mm). It is recommended not to inject it into the limbus.
  • The concentration (0.4 mg/ml) and time (not less than 3 minutes) can be modulated according to the patient (previous surgeries, multi-treated/congestive conjunctiva).
  • Implant Placement: It is placed in the superior quadrant, ideally between the 10-11 and 1 o'clock positions. The exact 12 o'clock position should be avoided so as not to affect the superior rectus muscle. The preferred locations are superonasal or superotemporal.
• Conjunctival Closure:
  • Dr. Delgado describes herself as “a bit obsessive about closure,” making sure to bring the Tenon's capsule well forward and leaving the center sealed (in addition to the anchoring sutures at the margins) to prevent short- or long-term leaks.
• Prevention of Intraoperative Hyperfiltration:
  • If overfiltration (“it filters a lot”) is observed during surgery (which can occur in patients with very high pressures, high myopes, or advanced age), it is recommended to cannulate the device with a stent suture (9-0 Prolene or 10-0 Nylon) to reduce the lumen in a controlled way and release it postoperatively if necessary.
• Combined Surgery:

• Combined with Phaco:
  • The general recommendation is to perform the procedures separately because the inflammation generated by phaco can lower the PreserFlo success rate by promoting fibrosis.
  • The inflamed aqueous humor would go to the filtration zone.
  • “It is preferable to try to do the procedures separately.” It is ideal to do it in a pseudophakic patient.
  • If it is combined, it is recommended to do it through two separate approaches (phaco via a temporal approach, PreserFlo via a superior approach).
  • Phaco should be done first, washing out the viscoelastic very thoroughly, and then placing the PreserFlo to avoid obstruction of the implant lumen (70 microns). Using viscoelastic in a standalone PreserFlo is not recommended.
  • If PreserFlo is done first and a significant cataract remains, Dr. Delgado prefers to wait at least 6 months to achieve good pressure control before operating on the cataract, although “the more time that can pass, obviously the better.” If the cataract has already been operated on, it does not matter if PreserFlo is done afterward.
• Combined with Retina Surgery:
  • Dr. Delgado has not performed simultaneous PreserFlo and retinal surgeries, but she has operated on patients with a history of retinal surgeries (vitrectomies, keratoplasties, scleral buckles).
  • These cases often fall outside the "off-label" indications of the studies.
  • The challenge is the success rate and whether the patient will achieve optimal pressure control, especially if the required pressure reduction is high.
  • In patients with intraocular silicone, sometimes simply removing the silicone improves pressure. Sometimes it's better to do "less than more," see how they progress with retinal procedures, and then combine glaucoma surgery if necessary.
  • Dr. Delgado has not had to remove a PreserFlo because of retinal complications, but she has coordinated with retina specialists to avoid the bleb area when injecting anti-VEGF agents. In extreme cases where an implant does not work and the visual potential is poor, cyclodestructive procedures could be considered.
• Management of Postoperative Complications:

• Postoperative Surveillance:
  • Initially, follow-up is similar to that of a traditional filtering surgery (first day, first week, then every two weeks during the first month). Rigorous topical corticosteroid use (even every 2-3 hours) is recommended during the first month to keep inflammation under control. Dexamethasone or triamcinolone are options. Atropinization in phakic patients during the first week is useful if there is no contraindication.
• Postoperative Hyperfiltration:
  • It can occur through the lumen of the tube or through peritubular filtration (if the tunnel is too large).
  • If peritubular leakage is detected intraoperatively, it is best to remove the tunnel and make a new one.
  • If overfiltration occurs postoperatively and there are choroidal detachments/a flat chamber, reforming with viscoelastic is not ideal; balanced salt solution is preferred.
  • If it is severe and does not resolve with medical management (atropinization, rest, head positioning), it is often necessary to reopen the conjunctiva and cannulate the device (place the stent suture) as would be done intraoperatively. Dr. Delgado had a case with choroidal detachments that resolved by cannulating the implant postoperatively.
• Fibrosis (Late/Early Failure):

• It's a common cause of failure. It's not Tenon's obstruction (unlike Xen45), but rather "fibrosis above the implant" (a plastron).
• If the pressure rises due to fibrosis, when surgically inspecting and lifting the conjunctiva, the device "does filter, it filters perfectly."
• Management involves reapplying Mitomycin C posteriorly (adjusting concentration/time) and releasing that fibrosis. These are “open revisions rather than needling.”

Other Iatrogenic Issues:

• If a tunnel does not turn out well intraoperatively (a “false passage”), it is better to create a new one without closing the previous one. In cases where the tube ends up tilted slightly upward (especially with thin conjunctiva), Dr. Delgado prefers to suture it lightly to the sclera to appose it and prevent extrusion.

Technology Adoption in Latin America:

• Although technologies arrive “a little later” than in other countries, this provides the advantage of having more evidence and prior experience (from Europe, Canada, etc.) to better select patients and improve the chances of success.
• Glaucoma used to be a more limited field in terms of treatment options, leading many patients to worsen despite eye drops, reaching late stages with poor quality of life.
• The concept of “interventional glaucoma” is key: being more interventional (in a good sense) to offer greater effectiveness, pressure control, and an improved quality of life for the patient.
• PreserFlo offers an important differentiator in “more advanced” glaucomas where angle-based MIGS are not enough, sometimes avoiding trabeculectomy or upfront valves.
• Cost is a major barrier in countries facing economic hardship. However, it can be compared with the cost of other technologies (expensive drops, premium intraocular lenses).
• In Colombia, "many health insurance plans cover it" and it's "less expensive than other mixed technologies."
• It is essential for the physician to offer the option to the patient, explaining the advantages and disadvantages, and that no glaucoma surgery is definitive.
• The final decision should be the patient's, guided by the physician. Information should not be withheld because the patient is presumed unable to pay ("the decision is the patient's, not mine").
• The arrival of these technologies in Latin America is a "fantasy" that "makes us better too because we grow in our technique" and "we also grow in options for people, which is ultimately the best." It's not a "premium option for the elite"; many patients can benefit by making an effort.

Relevant Quotes:

• “it came in as a wonderful alternative for glaucomas already in stages a little more advanced than what all the microinvasive therapies covered”
• “the reason is that since it is a, a bleb-forming surgery, well, it is going to have a better impact on the level of pressure reduction for patients who precisely need pressures, well, at lower levels, avoiding to some extent what traditional surgery is”
• “That is more or less the patient profile, glaucomas ranging from somewhat moderate to severe that require a, uh, significant pressure reduction, because it is a greater pressure reduction than what MIGS give, the traditional MIGS”
• “it's like a very explicit bridge, okay, it's a bridge between the least and the most, exactly”
• “I would tell you it is mandatory to do it with mitomycin, because our main enemy, without a doubt, is fibrosis, as in any procedure, even one that is more invasive”
• “But at the end of the day, if we don't use mitomycin, our failure rate is going to be very high”
• “the recommendation is to try to do things separately because in the end, even if it is a very, very well-done phaco, obviously, and a phaco of less, of, of not much difficulty, some extra inflammation is going to be generated anyway, and that, that aqueous humor, as we were just saying, is going to go precisely to the, to the filtration area and is going to lower our success rate”
• “So yes, there what, what, what you first have to keep in mind is that you say, well, the device has a very, very fine lumen, the probability of hypotony is pathophysiologically lower, but it can happen”
• “in patients where I see intraoperatively that it is filtering a lot, I prefer to cannulate the device with a stent suture”
• “reforming with viscoelastic, better not, ideally if you have to go in and reform, you reform with saline solution”
• “what a lot of people say is that it is very expensive, right? I mean, how am I going to offer it to my patient, and sometimes they don't even mention it anymore”
• “I think that when things reach us a little later we have a great advantage, and that is that they have already done it elsewhere, there is more evidence, about both the good and the bad, so that gives us plenty of possibilities to choose the patient better”
• “for me the arrival of this… not only brings one more option but also changes the mindset a bit, toward being able to offer something better, I believe better in many of the patients”
• “price is always going to come up… obviously they are going to have a cost”
• “to me it's a dream come true that all these things reach us, things that also make us better ourselves, because we grow in our technique… and we grow in, in, in options for people too, which in the end is the best thing”

Implications/Applicability:

• Dr. Delgado's experience suggests that PreserFlo is a valuable and viable tool in glaucoma management in Latin America, not only in markets with greater purchasing power.
• Its positioning as a bridge between MIGS and major surgeries is a useful framework for surgical decision-making.
• Emphasis on Mitomycin C and strategies to manage hyperfiltration and fibrosis are crucial for postoperative success.
• Considerations regarding combined surgery (separate if possible, careful management if not) are relevant practices.
• The discussion about cost underscores the need to inform the patient about all available options, allowing them to make the final decision.

Next Steps/Additional Questions (if this were a conversation):

• Explore longer-term follow-up of PreserFlo patients in Colombia.
• Detail the specific protocols for the use of Mitomycin C (concentration, time, area of application) according to the patient's profile.
• Discuss the bureaucratic process for health insurance approval and coverage in other countries in the region.
• Comparison of outcomes and learning curves with PreserFlo versus trabeculectomy in Latin American centers.