Glaucoma Drainage Devices (Tube Shunts)
Understanding Glaucoma Drainage Devices
Tube shunts offer a proven way to manage difficult glaucoma cases by creating a permanent alternative route for fluid to leave your eye. These small, durable implants work continuously to reduce pressure and protect your optic nerve when other approaches have fallen short.
Your eye naturally produces a clear fluid called aqueous humor to maintain its shape and nourish internal structures. In a healthy eye, this fluid drains out through tiny channels in the front of the eye. When you have glaucoma, these drainage channels become blocked or damaged, causing fluid to build up and pressure to rise, which damages the optic nerve and leads to vision loss over time.
A tube shunt creates a new pathway for this fluid to escape. The device consists of a thin, flexible silicone tube that sits inside the front chamber of your eye, where it collects excess fluid. This tube connects to a small plastic plate positioned on the outside of your eyeball, just beneath the conjunctiva (the clear tissue covering the white part of your eye). Fluid flows through the tube and pools around the plate, where your body naturally absorbs it, keeping your eye pressure stable.
We use two main categories of tube shunts, each designed to regulate fluid flow in different ways. Valved devices include a built-in mechanism that limits how much fluid can drain at once, which helps reduce the risk of pressure dropping too low right after surgery. Non-valved devices do not have this flow-restricting feature and are typically fitted with a temporary stitch or internal stent during surgery. Over several weeks, scar tissue forms around the plate in a controlled way, naturally regulating drainage.
Common examples include the Ahmed valve, Baerveldt implant, and Molteno device. Both valved and non-valved shunts have strong track records of success, and we select the best option for you based on your glaucoma type, eye anatomy, and any previous surgeries. During your consultation, we will discuss which device gives you the best chance of long-term pressure control.
Most patients with glaucoma start with prescription eye drops to lower pressure. If drops alone do not bring pressure down to a safe level, we may add laser therapy such as selective laser trabeculoplasty or perform a minimally invasive procedure. A tube shunt becomes necessary when these earlier treatments fail to protect your vision or when features of your eye make simpler surgeries unlikely to succeed.
In some cases, we may recommend a tube shunt earlier in your treatment plan based on your specific type of glaucoma or surgical history. Conditions that often lead to tube shunt surgery include:
- Multiple glaucoma medications that cannot lower pressure to your target range
- Laser treatments that have stopped working or are not suitable for your glaucoma type
- A previous trabeculectomy or other filtering surgery that has scarred over or failed
- Extensive scarring, inflammation, or other eye features that reduce the success rate of alternative surgeries
Who Needs a Tube Shunt
Not everyone with glaucoma requires a drainage device, but certain situations make tube shunts the best option for preserving your vision. We carefully evaluate your glaucoma type, treatment history, and overall eye health to determine whether this surgery is right for you.
If you have already undergone trabeculectomy or another drainage procedure that healed closed or no longer controls your pressure, a tube shunt is often our next recommendation. Eyes that have had prior surgery tend to form aggressive scar tissue, which makes repeat trabeculectomy less likely to succeed. Tube shunts resist scarring better than the delicate openings created in filtering surgery, giving you a better chance of long-term pressure control.
We will review your complete surgical history and current pressure readings to decide whether a drainage device offers you the most durable solution.
Certain forms of glaucoma are harder to manage with standard treatments and may benefit from a tube shunt earlier in your care. Neovascular glaucoma, which develops when abnormal blood vessels grow in the eye due to diabetes or retinal vein blockage, and uveitic glaucoma, caused by chronic inflammation, both create aggressive scarring that quickly defeats simpler surgeries.
Other challenging glaucoma types that may require a tube shunt include:
- Congenital glaucoma in children when other procedures fail
- Angle-closure glaucoma that does not respond to laser peripheral iridotomy or lens removal
- Glaucoma that develops after corneal transplant or other complex eye surgeries
- Medication-refractory glaucoma where drops and lasers provide insufficient pressure reduction
We may recommend a tube shunt as your first glaucoma surgery if your eye has features that make trabeculectomy risky or unlikely to work. Eyes with extensive scarring from prior trauma, very thin or abnormal conjunctival tissue, or active inflammation heal unpredictably after filtering surgery. A drainage device bypasses many of these issues by using a more durable implant and placing the drainage zone farther back on your eyeball.
If you have had multiple previous eye operations for retinal detachment, corneal problems, or complicated cataract surgery, we will determine whether a tube shunt gives you the strongest chance of stable pressure and preserved vision.
Before recommending a tube shunt, we perform a comprehensive eye examination to measure your current pressure, assess optic nerve damage, and map any vision loss. We use gonioscopy, a special lens technique, to inspect your drainage angle and check for scarring, inflammation, or abnormal blood vessels. We also review your medical history and every glaucoma treatment you have tried.
Diagnostic tests we use include:
- Tonometry to measure your intraocular pressure
- Ophthalmoscopy to examine your optic nerve for glaucoma damage
- Visual field testing to document any peripheral vision loss
- Optical coherence tomography, or OCT, to capture detailed images of your optic nerve and drainage structures
- Gonioscopy to view the inside drainage angle of your eye
- Ultrasound or other imaging when needed to see deeper structures
Preparing for and Undergoing Tube Shunt Surgery
Tube shunt implantation is a carefully planned procedure that requires some preparation on your part and coordination with your other doctors. Understanding what to expect before, during, and immediately after surgery will help you feel more confident and ensure the best outcome.
We will review all your medications and supplements during your preoperative visit. You should continue using your glaucoma eye drops unless we tell you otherwise, since stopping them can cause dangerous pressure spikes before surgery. If you take blood thinners such as aspirin, warfarin, or other anticoagulants, we will coordinate with your primary care doctor or prescribing specialist to decide whether you need to adjust them. Do not stop blood thinners on your own, as this can be dangerous.
Let us know about any herbal supplements you use, since some can affect bleeding or interact with anesthesia. Depending on the type of anesthesia planned, we may ask you to avoid eating or drinking for several hours before your procedure.
Because you will receive numbing and often sedating medication, you cannot drive yourself home after surgery. Arrange for a family member or friend to drive you to and from the surgical center. Plan to rest quietly for a few days afterward and have someone available to help with daily tasks like cooking and shopping while your vision is blurry and your eye is healing.
Items and arrangements to prepare include:
- A responsible adult to drive you home and stay with you the first night
- Comfortable clothing that does not pull over your head, such as button-up shirts
- A clean, organized space at home to store and use your postoperative eye drops
- Time off work or school, often at least one week depending on your job and recovery progress
Most tube shunt surgeries use local anesthesia combined with sedation. This means you may be lightly drowsy and relaxed, or more deeply sedated, while we numb the area around your eye with injections or specialized numbing drops. You should feel no pain during the procedure. General anesthesia may be used for children or adults who cannot remain still or prefer to be fully asleep.
Our anesthesia team monitors your vital signs throughout surgery to keep you safe and comfortable. You may feel some pressure or sense movement, but you should not experience sharp pain.
Once your eye is fully numb, we begin by making a small opening in the conjunctiva to access the white outer wall of your eyeball. We carefully position the drainage plate on the surface of your eye, usually in the upper outer area, and secure it with tiny permanent stitches. Next, we create a narrow pathway into the eye and gently thread the silicone tube through it.
Depending on your eye anatomy and whether you have had previous surgery, the tube tip may be placed in the front chamber of your eye, behind the iris, or farther back with the help of a vitrectomy if needed. We position the tip where it can collect fluid without touching your iris, cornea, or other sensitive structures. We may temporarily restrict the tube with a stitch or insert a small dissolvable stent to control drainage in the first few weeks while your body forms a controlled capsule around the plate. Finally, we close the conjunctiva over the device with dissolvable stitches and apply antibiotic ointment and a protective shield.
The entire device remains hidden beneath the surface tissues of your eye. Only your eye doctor can see it during exams.
The procedure typically takes between 45 minutes and 90 minutes, depending on the complexity of your case. We usually operate on one eye at a time, as same-day surgery on both eyes is uncommon and only considered in special situations. After surgery, you rest in a recovery area for about an hour while the sedation wears off and we check your initial pressure. Most patients go home the same day with a patch or shield over the eye and detailed instructions for aftercare.
You will receive prescriptions for antibiotic and anti-inflammatory eye drops to start the next day. We will schedule your first follow-up visit within one to two days to confirm your eye is healing well and your pressure is in a safe range.
Risks and Possible Complications
Like all eye surgeries, tube shunt implantation carries risks that range from mild and temporary to serious and vision-threatening. We monitor you closely to detect and manage complications early, but it is important you understand what can happen so you know when to seek help.
Some complications are more common in the early healing period and can often be managed with medication adjustments, close monitoring, or minor additional procedures. We see you frequently in the first weeks to catch these problems before they affect your vision.
Possible early complications include:
- Hypotony, or pressure that drops too low, causing blurred vision or other issues
- Shallow anterior chamber if fluid drains too quickly or leaks from the wound
- Choroidal effusion or choroidal hemorrhage, fluid or bleeding in the layers behind the retina
- Hyphema, bleeding into the front chamber of the eye that usually clears on its own
- Early high pressure, especially with non-valved devices before full drainage begins
- Tube blockage from blood, fibrin, or other debris
- Wound leak requiring additional stitches or a tissue patch
- Infection or severe inflammation requiring intensive treatment
While most patients do well in the long term, complications can occur months or even years after surgery. Regular follow-up visits allow us to detect these changes and intervene before your vision is affected. Some late problems require adjustments to your medications, laser or needle procedures in the office, or surgical revision.
Possible long-term complications include:
- Tube erosion through the overlying conjunctiva, requiring a patch graft
- Tube blockage from scar tissue or inflammatory material
- Tube movement or migration that may cause irritation or damage to nearby structures
- Corneal damage if the tube touches the inner cornea, or gradual loss of corneal cells over time leading to clouding
- Double vision or eye movement problems if the plate affects nearby eye muscles
- Cataract development or progression in patients who still have their natural lens
- Encapsulated bleb, thick scarring around the plate that limits drainage
- Persistent low pressure causing vision problems or structural changes in the eye
- Chronic inflammation or infection around the device, though rare with proper care
Recovery and Aftercare Following Surgery
Your recovery after tube shunt surgery typically takes several weeks, with gradual improvement in comfort and vision. Following your postoperative instructions carefully and attending every follow-up appointment are critical to successful healing and long-term pressure control.
It is normal for your eye to be red, swollen, and uncomfortable for the first few days after surgery. You may notice a gritty or scratchy sensation, mild aching, or a feeling of pressure around your eye. Your vision will be blurry at first from swelling and from the ointment we apply. You might see extra floaters or shadows as your eye adjusts to the device.
Common early symptoms include:
- Redness that gradually fades over several weeks
- Mild to moderate discomfort that improves with over-the-counter pain relievers
- Blurred or hazy vision for the first week or two
- Sensitivity to light that decreases as healing progresses
You will use antibiotic drops to prevent infection and steroid drops to reduce inflammation and control scarring around the device. We will give you a detailed schedule, often starting with drops every few hours and then gradually tapering the frequency over several weeks or months. Always wash your hands before using drops, tilt your head back, pull down your lower lid, and apply one drop without letting the bottle tip touch your eye or eyelashes.
Using your drops exactly as prescribed is critical to successful healing. Missing doses or stopping too soon can lead to infection or excessive scarring that blocks the device. Steroid drops can raise eye pressure in some patients, so we monitor your pressure closely at every visit and adjust your medications as needed. Keep all your drop bottles clean, store them as directed, and bring them to every follow-up appointment.
Activity restrictions vary based on your individual healing, but most patients are asked to avoid actions that could jar the eye, suddenly raise pressure, or introduce bacteria for the first few weeks. Do not rub or press on your eye, even if it itches, as this can damage the healing tissues or move the device. Skip swimming, hot tubs, and saunas until we clear you, since these can cause infection.
Common restrictions include:
- No eye rubbing or touching the surgical area
- No swimming, diving, or water sports for at least four weeks
- No heavy lifting over ten pounds or strenuous exercise in the early weeks
- Wear your protective eye shield at night to prevent accidental injury while sleeping
- Avoid dusty or dirty environments that could irritate your eye
- Avoid eye makeup until your eye doctor clears you
- Shower carefully and avoid getting water or soap directly in your eye
- Ask when it is safe to resume driving, as this depends on your vision recovery
We will see you one or two days after surgery for your first postoperative check. During this visit, we measure your eye pressure, examine the device position, and make sure there are no early complications. You will return again at one week, then at regular intervals over the first few months as your eye heals and the device begins working fully.
We may adjust your drop schedule, remove stitches, or perform minor procedures to optimize fluid flow through the tube. Keeping every appointment is essential because we monitor your pressure closely and catch problems early. Even after your eye has fully healed, you will need lifelong follow-up visits every few months to ensure the device continues working properly.
Call our office immediately if you notice sudden vision loss, severe pain that does not improve with over-the-counter medicine, or a large increase in redness or swelling. These symptoms can signal serious complications like infection, bleeding inside the eye, or dangerously low or high pressure. A sudden shower of new floaters, flashing lights, or a curtain or shadow across your vision can indicate retinal detachment and requires urgent evaluation the same day.
Seek immediate care if you experience:
- Sudden decrease in vision or complete vision loss
- Severe or worsening eye pain
- Heavy discharge, especially yellow or green
- Rapidly increasing redness or swelling
- Nausea, vomiting, or headache with eye pain
- New or worsening light sensitivity with decreasing vision
Long-Term Outcomes and Monitoring
Tube shunts can provide effective long-term control of eye pressure in many patients, though outcomes vary based on your glaucoma type, disease severity, and individual healing response. Lifelong monitoring ensures your device continues working and your vision remains stable.
Clinical studies show that tube shunts successfully lower eye pressure in a majority of patients over several years. Success is usually defined as achieving a target pressure reduction with or without additional glaucoma medications and avoiding the need for further surgery. However, outcomes differ widely depending on your type of glaucoma, how advanced your disease is, whether you have had previous surgeries, and which device we use.
Patients with neovascular glaucoma, uveitic glaucoma, or multiple prior surgeries may have different success rates than those with primary open-angle glaucoma and no previous operations. Some patients eventually need additional procedures, adjustments, or even a second drainage device if pressure rises again. Most people experience significant pressure reduction and stabilization of vision with a tube shunt, though the device does not restore vision already lost to glaucoma.
Even after your eye has fully healed, we will monitor you every three to six months for life. During these visits, we measure your intraocular pressure, examine the appearance of the tube and plate, and check your optic nerve and visual field for any changes. We look for signs that the device is draining too much or too little fluid, or that scar tissue is forming in a way that could block flow.
We may use optical coherence tomography or other imaging tests and special lenses to see the tube tip inside your eye. These routine checks allow us to detect changes early and adjust your medications or recommend additional procedures if needed to maintain stable pressure and protect your remaining vision.
Many patients still require one or more glaucoma eye drops after tube shunt surgery to reach their target pressure. The device significantly reduces pressure in most cases, but it may not eliminate the need for all medications, especially in advanced or aggressive glaucoma. We tailor your drop regimen to your individual pressure goals and reassess it at every visit.
Some people eventually stop all glaucoma drops if their device maintains excellent pressure control on its own. Others use fewer medications than before surgery, which can improve quality of life and reduce side effects. We also offer advanced glaucoma treatments such as Durysta and iDose, sustained-release medication options that can reduce the need for daily drops. We will work with you to find the simplest regimen that keeps your pressure safe and your vision stable.
Frequently Asked Questions
We often hear similar questions from patients considering or recovering from tube shunt surgery. Here are answers to some of the most common concerns.
The drainage plate is securely stitched to the surface of your eyeball, and the tube is carefully positioned and often anchored as well, so movement is uncommon. In rare cases, trauma to the eye or gradual tissue changes can cause the tube to shift slightly. We monitor for this at every visit by examining the tube position with specialized lenses. If the tube does move enough to cause problems such as rubbing on the cornea or iris, or if it becomes displaced out of the eye, we can reposition it with a minor surgical procedure.
You should not see the device when you look in the mirror because it sits beneath the conjunctiva and is usually covered by your upper eyelid. Some patients notice a slight, painless elevation or firmness in the area where the plate rests if they gently touch the closed eyelid, but this rarely causes discomfort once healing is complete. You will not feel the tube inside your eye during normal daily activities, and it should not interfere with blinking or moving your eye. If you do experience persistent irritation or a foreign-body sensation, let us know so we can check the device position.
Both procedures create a new drainage pathway to lower eye pressure, but they work in different ways and have different advantages. Trabeculectomy makes a small flap in the wall of the eye to let fluid filter out and form a bleb, a blister-like area under the conjunctiva where fluid collects before being absorbed. A tube shunt uses a permanent silicone implant to direct fluid to a plate, which tends to resist scarring better than the delicate opening created in trabeculectomy. We may choose a tube shunt if you have factors that make trabeculectomy less likely to succeed, such as previous surgery, inflammatory conditions, or neovascular glaucoma. Dr. Salman Dar and Dr. Remil Simon have extensive experience with both tube shunts and trabeculectomy and will recommend the approach best suited to your individual situation.
Most current glaucoma drainage devices are made from non-magnetic materials such as silicone, polypropylene, or other plastics that are generally safe in MRI machines. However, some older models or certain device components may have specific safety conditions depending on the MRI strength and scanner type. Always inform your MRI technologist and radiologist that you have a glaucoma implant before any scan. Bring your implant identification card or operative report details if available so they can confirm the device type and follow appropriate safety protocols.
If your pressure rises because the tube becomes blocked with blood, inflammatory material, or tissue ingrowth, or if too much scar tissue forms around the plate and prevents drainage, we have several options to restore function. We may adjust your glaucoma medications, use a laser or needle procedure in the office to open scar tissue around the plate, or perform a minor surgical revision to clear the tube or reposition it. In some cases, we may need to implant a second drainage device in a different area of your eye if the first one can no longer provide adequate control. Our team has experience managing complex, medication-refractory glaucoma and will create a personalized plan to preserve your vision.
Advanced Glaucoma Care at Dulles Eye Associates
If you have been told you need a tube shunt or your current glaucoma treatments are not controlling your pressure, our fellowship-trained team is ready to help. At Dulles Eye Associates, Dr. Salman Dar and Dr. Remil Simon specialize in advanced glaucoma surgery, including tube shunts, trabeculectomy, and minimally invasive procedures such as iStent, Hydrus Microstent, and Kahook Dual Blade, and we offer the latest technologies including OCT imaging and visual field testing to monitor your condition. We serve patients throughout the DC Metro Area and Northern Virginia region with convenient locations in Lansdowne, Reston, and Annandale, and we are committed to preserving your vision with personalized, compassionate care.
Dr Salman Dar is the best and professional doctor by my husband surgery was amazing I really recommend Dr. Dar and staff are so good.
Fariba Kia
Dr. Ahmed Nasrullah and staff are outstanding—kind, professional, and thorough. Restored my 20/20 vision and a bright and clear view of the future. Highly recommend for his services.
Ernest Vitello
The whole experience of getting LASIK was easy and stress-free. Scheduling appointments was seamless, and everyone was kind and made sure the process wasn’t scary.
Matt Horan
Dr. Dar has a high level of expertise and patience, answering all my questions about my cataract surgeries. He follows up on details with other staff and ensures all concerns are taken care of.
Margaret Sedlacek
Doctors, nurses and staff handle each patients concerns with great care and respect. They are the place to go for regular exams or even for lasik!
Hafiz Bhuyan