PreserFlo MicroShunt
Understanding the PreserFlo MicroShunt
The PreserFlo MicroShunt is a soft, flexible tube about the size of an eyelash, made from a special plastic material called SIBS. This material has been used safely in heart stents for many years and is biocompatible, meaning it typically causes a low inflammatory response in the body. While the device is well tolerated by most patients, scarring, inflammation, and other tissue reactions can still occur. Our surgeon places one end of the tube inside the front chamber of your eye and tunnels the other end under the conjunctiva, the clear tissue covering the white of your eye.
The device measures only 8.5 millimeters long and less than half a millimeter wide, with a fixed internal opening designed to control fluid drainage. Because it is so small and placed under tissue, it is usually not visible once the eye has healed, though the small fluid-filled bleb area may be noticeable in some patients.
Your eye constantly produces a clear fluid called aqueous humor that normally drains through tiny channels. In glaucoma, these natural drainage channels become blocked or work poorly, causing pressure to build up and damage the optic nerve. The MicroShunt creates an alternative route for this fluid to exit your eye.
Fluid flows through the tiny tube and collects in a small space under the conjunctiva, forming a small blister-like area called a bleb. Your body then absorbs this fluid naturally. This process happens continuously and helps lower the pressure inside your eye to a safer level. The bleb requires lifelong monitoring because it can be vulnerable to infection and thinning.
Trabeculectomy is a traditional glaucoma surgery that creates a drainage flap in the eye without using a permanent tube. It can achieve very low eye pressures but requires more tissue manipulation and may carry higher risks of certain complications. The PreserFlo MicroShunt offers a different approach using a fixed-size tube to control drainage, though outcomes vary depending on surgeon experience, your individual healing response, and how well the bleb functions over time.
- PreserFlo uses a fixed-size tube to limit early hypotony, while trabeculectomy creates a variable opening
- Traditional tube shunts are larger and may have a plate to anchor them, while PreserFlo is shorter and simpler
- PreserFlo may have faster visual recovery than trabeculectomy in some cases
- All three options involve creating a bleb under the conjunctiva
- Each procedure has different risks, and your surgeon will help you weigh the benefits and trade-offs
The PreserFlo MicroShunt works best for patients with open-angle glaucoma whose eye pressure is not controlled well enough with medications or laser treatment. You may be a good candidate if you have moderate to advanced glaucoma damage and need significant pressure reduction. Our eye doctor will evaluate your specific type of glaucoma, current eye pressure, optic nerve health, and visual field loss.
Suitability also depends on the health of your conjunctiva and your body's tendency to form scar tissue. Factors such as prior eye surgery, especially conjunctival or surface procedures, ocular surface disease, uveitis, neovascular glaucoma, dry eye, and scarring can affect both the success of the surgery and the risk of complications. Ability to attend frequent follow-up visits, especially in the first weeks after surgery, is essential.
This surgery is not typically recommended for certain types of angle-closure glaucoma, though some patients with mixed-mechanism disease or those who have had lens-based treatment may still be considered depending on the anatomy of the front of the eye. Your overall eye health and individual risk factors will guide whether PreserFlo is right for you.
When Our Eye Doctor May Recommend the PreserFlo MicroShunt
Before recommending the PreserFlo MicroShunt, we evaluate all treatment options available to control your glaucoma. Every patient is different, and the best approach depends on the severity of your disease, your response to prior treatments, and your overall health.
- Continuing or adjusting your current glaucoma medications
- Selective laser trabeculoplasty or other laser treatments to improve drainage
- Cataract surgery, which can lower eye pressure in some patients
- Trabeculectomy, a traditional filtration surgery
- Tube shunt implants for more advanced or complex cases
- Other minimally invasive glaucoma surgeries when appropriate for your disease stage
- Cyclophotocoagulation or other procedures for select cases
If you are already using multiple glaucoma eye drops and your pressure is still above your target range, medications alone may not be enough to protect your vision. Some patients have difficulty tolerating the side effects of glaucoma drops or find it hard to use them consistently. The MicroShunt may reduce your dependence on daily medications while achieving better pressure control, though some patients will still require one or more drops even after surgery.
We measure your eye pressure at each visit and compare it to the target pressure needed to slow or stop further vision loss. When medication fails to reach that goal consistently, surgery becomes a necessary next step.
Glaucoma causes permanent damage to the optic nerve, which cannot be reversed. If testing shows you have already lost significant peripheral vision or your optic nerve shows moderate to severe cupping, aggressive pressure lowering becomes critical. The PreserFlo MicroShunt can often achieve lower pressures than medications alone, giving your remaining nerve fibers the best chance of survival.
- Visual field tests show areas of vision loss in both eyes
- OCT imaging reveals thinning of the nerve fiber layer
- Your optic nerve cup-to-disc ratio is increasing despite treatment
- Pressure continues to cause progression even on maximum medical therapy
Some patients and doctors prefer the PreserFlo MicroShunt over trabeculectomy because it may offer a more predictable recovery with a different risk profile. The fixed lumen of the tube creates consistent drainage, whereas trabeculectomy outcomes can vary more widely. If you have concerns about the risks of traditional surgery or have factors that make trabeculectomy more challenging, we may discuss PreserFlo as an alternative.
Recovery milestones tend to be more uniform with the MicroShunt, and the risk of extremely low pressure in the first weeks after surgery may be lower in some cases. However, both procedures are effective options, each with different benefits and risks, and our eye doctor will discuss them with you.
Open-angle glaucoma is the most common form and occurs when the drainage angle inside your eye is anatomically open but does not function efficiently. The PreserFlo MicroShunt bypasses the natural drainage system entirely, making it particularly effective for this type of glaucoma. We confirm your glaucoma type through gonioscopy, a painless exam that lets us view the drainage angle.
Some forms of angle-closure glaucoma or secondary glaucoma may require alternative surgeries. In cases of mixed-mechanism disease or chronic angle-closure after lens extraction, PreserFlo may still be an option if the anterior chamber is adequately formed. We will tailor our recommendation based on the specific characteristics of your condition.
Preparing for Your PreserFlo MicroShunt Procedure
Before scheduling your PreserFlo surgery, we will perform a thorough eye examination to ensure you are a good candidate. This includes measuring your eye pressure, examining your optic nerve, and reviewing your most recent visual field test. We also use optical coherence tomography to assess the thickness of your nerve fiber layer and look for signs of ongoing damage.
- Gonioscopy to confirm the drainage angle is open
- Measurement of corneal thickness, which affects pressure readings
- Evaluation of the conjunctiva to choose the best bleb location
- Review of any previous eye surgeries or scarring
You should continue all your glaucoma eye drops as prescribed right up until surgery unless our eye doctor tells you otherwise. If you take blood thinners such as aspirin, warfarin, or other anticoagulants, let us know well in advance. In many cases, you can continue these medications, but we may coordinate with your primary care doctor or cardiologist to ensure it is safe.
Bring a complete list of all medications, supplements, and vitamins you take to your pre-operative visit. Some herbal supplements can increase bleeding risk and may need to be stopped a week or more before surgery.
You will not be able to drive yourself home after PreserFlo surgery because you will receive sedation and have one eye patched or shielded. Arrange for a responsible adult to drive you to and from the surgery center and stay with you for at least the first night. Your vision in the operated eye will be blurry for several days, so having help with daily activities is important.
Plan to take at least a few days off from work and avoid strenuous activities during the first week. Stock up on easy-to-prepare meals and make sure you can rest comfortably at home.
We will give you specific instructions about when to stop eating and drinking before surgery. Follow the anesthesia guidelines provided by our surgical team, as restrictions may differ for solid foods versus clear liquids. You can usually take essential oral medications with a small sip of water on the morning of surgery, but confirm this with our team. Wear comfortable, loose-fitting clothing and leave valuables at home.
- Bring your insurance cards and photo identification
- Bring a list of all medications you currently take
- Leave contact lenses out and wear your glasses instead
- Do not wear makeup, lotions, or perfumes on surgery day
- Arrive at the scheduled time so we can complete all pre-operative checks
What Happens During PreserFlo MicroShunt Surgery
The PreserFlo procedure is performed under local anesthesia to numb your eye completely so you feel no pain. We typically give you an injection of numbing medicine around the eye or use a combination of numbing drops and a small injection. You will also receive sedation through an IV to help you relax and feel drowsy during the procedure.
Some patients remember parts of the procedure despite sedation, while others have little or no memory of it. Comfort is typically well controlled. You will be awake enough to follow simple instructions, such as looking in a certain direction, but you should not feel anxious or uncomfortable.
Once your eye is numb, our surgeon creates a small opening in the sclera, the white outer wall of your eye. The PreserFlo MicroShunt is carefully inserted so that one end sits in the anterior chamber, the fluid-filled space at the front of your eye. The other end is positioned under the conjunctiva, where fluid will collect and drain.
Our surgeon may also apply an anti-scarring medication called mitomycin C to the area to reduce the chance of excessive scarring that could block drainage. The conjunctiva is then closed over the device with very fine stitches. The entire implant remains hidden beneath the surface of your eye.
The PreserFlo MicroShunt surgery itself usually takes between 30 and 45 minutes from start to finish. You will spend additional time in the pre-operative area getting prepared and in the recovery room afterward, so plan to be at the surgery center for several hours total. The actual time in the operating room is relatively short compared to other glaucoma surgeries.
Our surgical team works efficiently while ensuring every step is performed with precision. You will be kept informed throughout the process.
After the surgery is complete, you will be moved to a recovery area where nurses will monitor you as the sedation wears off. We will make sure you are comfortable and alert before you go home. Your eye will be covered with a shield or patch to protect it during the first day.
- You may feel groggy or sleepy for a few hours after sedation
- Nurses will give you pain medication if you have discomfort
- We will provide written instructions for eye drops and aftercare
- You will receive a prescription for antibiotic and anti-inflammatory drops
- Depending on facility protocols, your eye pressure may be checked before discharge
Recovering After PreserFlo MicroShunt Surgery
Your eye will be red and may feel scratchy, irritated, or mildly sore for the first several days after PreserFlo surgery. This is normal and should gradually improve. You might notice some swelling of the eyelid and a feeling of pressure or fullness. Your vision in the operated eye will be blurry at first, and you may see shadows or halos around lights.
The redness comes from the surgery on the white part of your eye and from the bleb forming under the conjunctiva. As healing progresses over the next few weeks, the redness will fade. Some people also notice a small blister-like bump on the white of the eye where the bleb is located, which is expected.
After surgery, you will need to use prescription antibiotic and anti-inflammatory eye drops several times a day to prevent infection and control inflammation. We will give you a detailed schedule, which typically starts with drops four times daily and then tapers over several weeks. Using these drops exactly as prescribed is critical to your healing and the success of the surgery.
- Wash your hands thoroughly before putting in drops
- Tilt your head back and pull down your lower eyelid to create a pocket
- Avoid touching the dropper tip to your eye or fingers
- Wait at least five minutes between different types of drops
- Set reminders on your phone so you do not miss doses
For the first week after PreserFlo surgery, avoid bending over, heavy lifting, straining, and vigorous exercise. These activities can increase pressure inside your eye and interfere with healing. Do not rub or press on your eye, and avoid getting water directly in your eye when washing your face or showering. Wear the protective shield at night to prevent accidentally bumping your eye while you sleep.
Most patients can return to light activities and desk work within a few days, but wait at least one to two weeks before resuming exercise or anything strenuous. Avoid swimming, hot tubs, and dusty or dirty environments for at least a month. Do not wear contact lenses or eye makeup until our eye doctor clears you to do so. Our eye doctor will let you know when it is safe to return to all your normal activities based on how well your eye is healing.
We will see you the day after surgery to check your eye pressure and examine the bleb. Additional follow-up visits are scheduled based on how your eye is healing and may be more frequent in the first month. Typical visits occur at one week, then multiple times in the first month, followed by visits at three months and six months after surgery. These appointments are essential because we monitor for complications and adjust your medications as needed. If your pressure is too high or too low, we may need to intervene early to optimize your outcome.
During these visits, we also check for signs of infection, inflammation, or scarring that could affect the function of the MicroShunt. In some cases, we may perform additional treatments such as massaging the bleb area, needling to break up scar tissue, or injecting medications to improve drainage. Attending every scheduled appointment helps us catch and address any issues before they become serious.
Your eye pressure will fluctuate during the first few weeks to months after PreserFlo surgery as the bleb matures and your eye adjusts to the new drainage pathway. Some patients reach stable, low pressure within the first month, while others take two to three months or longer. The healing process is gradual, and scar tissue formation around the bleb influences how well fluid drains.
We will track your pressure closely during follow-up visits and may adjust your post-operative medications to encourage proper bleb function. Most patients achieve significant pressure reduction that lasts for years, though some may need additional treatments or medications over time.
Possible Risks and When to Seek Urgent Care
Mild discomfort, redness, blurred vision, and light sensitivity are common in the first few weeks after PreserFlo surgery and usually resolve as your eye heals. You may also see floaters or experience mild tearing. These side effects are generally not dangerous and improve with time and proper use of your prescribed eye drops.
Some patients notice a small amount of blood on the white of the eye, which looks alarming but is typically harmless and will clear on its own. If any symptom seems severe or is getting worse instead of better, contact our office for guidance.
Call our office right away or seek emergency care if you experience sudden vision loss, severe eye pain that is not relieved by over-the-counter pain medication, or a large increase in redness. Other urgent warning signs include flashes of light, a curtain or shadow blocking your vision, or seeing many new floaters suddenly. These symptoms could indicate a serious complication that needs immediate treatment.
- Eye pressure that drops too low, causing very blurry vision or pain
- Signs of infection such as thick discharge, severe redness, or fever
- Bleeding inside the eye that clouds your vision
- Sudden swelling of the eyelid or eye that worsens rapidly
- Watery leakage from the eye or a sudden wet sensation, which may indicate a bleb leak
- Increasing pain, redness, light sensitivity, and discharge even months or years after surgery, which may signal blebitis or infection inside the eye
- A new white spot or thinning area over the implant, or feeling of something scratching, which may indicate device exposure or erosion
- Severe headache with nausea or vomiting and markedly decreased vision, which raises concern for very high eye pressure
Although the PreserFlo MicroShunt is generally safe, rare complications can occur. These include infection inside the eye, called endophthalmitis, which requires urgent antibiotic treatment. We monitor carefully at every follow-up visit to detect any problems early and intervene before permanent damage occurs.
- Hypotony, or pressure that remains too low for too long, which can lead to a shallow anterior chamber, vision changes, or damage to the retina
- Choroidal effusion or detachment, a buildup of fluid behind the retina that can occur when pressure is too low
- Hypotony maculopathy, a condition where persistently low pressure causes wrinkling of the macula and vision loss
- Bleb leak, where fluid seeps through a thin area of the bleb, raising infection risk
- Blebitis, an infection of the bleb tissue that can progress to endophthalmitis if not treated promptly
- Progression of cataract in the operated eye, which may require cataract surgery sooner than expected
- Corneal edema or endothelial cell loss, especially if the tube position is too close to the cornea
- Implant exposure or erosion through the conjunctiva, requiring surgical repair or repositioning
- Bleeding inside the eye or suprachoroidal hemorrhage, which is rare but can be severe
- Need for additional postoperative procedures such as needling, antifibrotic injections, bleb revision, or placement of another device
Clinical studies show that the PreserFlo MicroShunt can effectively lower eye pressure for several years in many patients. Outcomes vary depending on study design, baseline disease severity, length of follow-up, and individual healing responses. Many patients achieve pressures in the low to mid teens, though results are not identical for everyone.
Some patients will still need one or two glaucoma drops to reach their target pressure even after surgery. Others may experience gradual scarring over time that reduces the effectiveness of the shunt, and a small percentage may need a second surgery or additional procedures to maintain pressure control. Overall, the PreserFlo MicroShunt offers significant pressure reduction for many people with moderate to advanced glaucoma, with long-term durability that may require ongoing monitoring and occasionally additional treatment.
Frequently Asked Questions
Many patients can reduce the number of glaucoma medications they use after PreserFlo surgery, and some are able to stop drops altogether if their pressure remains low enough. However, there is no guarantee that you will be completely medication-free. We evaluate your pressure at each follow-up visit and restart or continue certain drops if needed to keep your pressure at a safe level for your particular stage of glaucoma.
Most people cannot see the PreserFlo MicroShunt itself because it sits under the conjunctiva, but you may notice a small bleb on the white part of your eye near the upper eyelid. The appearance of the bleb varies from patient to patient. Some blebs are barely noticeable, while others can be visible and may be a cosmetic concern for some people. You should not feel the device once your eye has healed, though the area may feel slightly different when you touch the outside of your closed eyelid. The device does not interfere with your daily life or comfort, and the bleb is monitored long-term to ensure it remains healthy.
If scarring blocks the drainage pathway or the bleb stops functioning, your eye pressure may start to rise again. We monitor for this at follow-up visits by checking your pressure and examining the bleb. Sometimes we can restore function with a procedure called needling, in which we use a tiny needle to break up scar tissue around the bleb. In other cases, we may add medications or recommend a second surgery to place another drainage device or perform a different type of glaucoma procedure.
Coverage for the PreserFlo MicroShunt varies by insurance plan, geographic region, and individual payer policies. Some insurance plans, including certain Medicare plans, may cover the procedure when it is medically necessary to treat glaucoma that is not controlled by other means. Prior authorization may be required. Our billing team can verify your specific coverage and let you know if you will have any out-of-pocket costs such as copays or deductibles. Do not assume coverage is automatic. Contact your insurance company before surgery if you have questions about benefits.
Minimally invasive glaucoma surgeries, or MIGS, typically cause less trauma to the eye and have faster recovery times than PreserFlo, but they usually do not lower pressure as much. MIGS procedures work best for mild to moderate glaucoma and often still require some medications afterward. The PreserFlo MicroShunt is considered more effective for patients with moderate to advanced disease who need significant pressure reduction. Our eye doctor will help you weigh the trade-offs between a quicker, gentler procedure and the degree of pressure lowering you need.
Yes, cataract surgery can be performed safely after you have a PreserFlo MicroShunt in place. In fact, some patients develop cataracts years after glaucoma surgery, and removing the cataract can even help lower eye pressure slightly in some cases. Our surgeon will take extra care to avoid disturbing the bleb and the MicroShunt during cataract surgery. If you already have a significant cataract at the time of your glaucoma surgery, we may consider combining both procedures into one operation to reduce the number of surgeries you need.
Getting Help for PreserFlo MicroShunt
If you have been diagnosed with glaucoma and are struggling to control your eye pressure with medications, the PreserFlo MicroShunt may offer a solution to protect your vision. Our eye doctor will perform a thorough evaluation to determine if you are a good candidate and will explain all your surgical options in detail. Early treatment and careful follow-up give you the best chance of preserving your sight for years to come.