Glaucoma surgery in San Antonio: trabeculectomy and tube shunts
Proven filtering surgery for glaucoma that needs a lower pressure
When drops and lasers aren’t lowering eye pressure enough, or when glaucoma is advanced or progressing, filtering surgery is the most powerful way to protect the vision you still have. Trabeculectomy is the classic procedure, and tube shunts are a trusted alternative for advanced glaucoma and eyes that have had previous surgery. At San Antonio Eye & Face Institute, Dr. Relief Jones, III, a glaucoma fellowship-trained ophthalmologist, performs trabeculectomy and tube shunt surgery, mainly placing Ahmed valves and using Baerveldt implants when they’re the better choice. This page explains how each works, who they’re for, and what to expect.
Reviewed by Dr. Relief Jones, III, M.D. · Last updated: October 11, 2026
At a glance
| Trabeculectomy | Ahmed valve | Baerveldt implant | |
|---|---|---|---|
| What it is | Classic filtering surgery with a scleral flap | Tube shunt with a built-in valve | Tube shunt without a valve and with a larger plate |
| How fluid drains | To a bleb under the conjunctiva | Through a tube to a plate on the eye | Through a tube to a larger plate on the eye |
| Implant left in eye? | No | Yes | Yes |
| Best for | Moderate to advanced glaucoma needing a low pressure | Advanced glaucoma, prior surgery, some secondary glaucomas | Advanced glaucoma needing more pressure lowering |
| At our practice | Performed | The tube shunt Dr. Jones mainly uses | Used when it’s the better choice |
| Where | American Surgery Center | American Surgery Center | American Surgery Center |
When is glaucoma surgery needed?
Lowering eye pressure is the only proven way to slow glaucoma. Most patients start with drops and often a laser such as [SLT]. Surgery is recommended when:
- Drops and laser aren’t lowering pressure enough
- The optic nerve damage or visual field loss is advanced or progressing
- You can’t tolerate your drops or can’t use them reliably
- A lower target pressure is needed than minimally invasive glaucoma surgery (MIGS), such as goniotomy or microstents, can provide
Filtering surgery and tube shunts don’t cure glaucoma and can’t restore vision already lost, but they can protect the vision you still have.
How filtering surgery works
Fluid (aqueous humor) is constantly made inside the eye and needs to drain out. Glaucoma surgery creates a new drainage route that bypasses the eye’s blocked natural drain. In trabeculectomy, fluid flows to a small reservoir under the conjunctiva (the thin clear membrane covering the white of the eye), called a bleb, where it’s absorbed. In a tube shunt, fluid flows through a small tube to a plate on the outside of the eye. Either way, the goal is a lower, steadier eye pressure.
Trabeculectomy
What is it?
For decades, trabeculectomy has been the standard surgery for glaucoma that isn’t controlled with drops or laser. It’s often described as the “gold standard” for lowering eye pressure, and it can reach very low pressures, which matters for advanced glaucoma.
How it’s done
After the eye is numbed using a nerve block and you’re relaxed with IV sedation:
- The surgeon creates a thin, partial-thickness flap in the sclera (the white of the eye), beneath the conjunctiva.
- A small opening is made under the flap into the eye, and fluid can now drain through it.
- An anti-scarring medicine (mitomycin C) is usually applied to help the new drainage route stay open.
- The flap is closed with fine sutures that control how much fluid escapes, and the conjunctiva is closed over it.
- Fluid drains under the flap to a bleb, where it’s absorbed.
Who is it for?
People with moderate to advanced glaucoma, or glaucoma that’s progressing on maximal treatment, who need their pressure lowered substantially. It’s especially valuable when a very low target pressure is needed. Dr. Jones will tell you whether trabeculectomy or a tube shunt is the better fit for your eye.
Recovery and follow-up
Trabeculectomy needs careful follow-up. In the first weeks, we see you frequently to check your pressure and your bleb, and we may adjust or release sutures to fine-tune the flow, massage the bleb, or perform a small procedure called needling to keep the bleb working. You’ll use drops as directed (including an anti-inflammatory) and may need to limit certain activities for a few weeks until your eye heals. Your vision may be blurry at first, and the bleb needs lifelong attention.
Risks
Trabeculectomy is effective, but it has more risks than minimally invasive options. They include pressure that’s too low (hypotony) or too high, a leaking bleb, a scarred bleb that stops working, infection of the bleb or inside the eye (uncommon but serious, and a lifelong consideration), bleeding, inflammation, cataract formation or progression, and the need for additional procedures. It isn’t possible to list every possible complication, and no outcome can be guaranteed.
Tube shunts (glaucoma drainage devices)
What is a tube shunt?
A tube shunt is a small silicone tube attached to a plate that’s placed on the outside of the eye, behind the muscles that move the eye. The tube carries fluid from inside the eye to the plate, where a thin capsule of tissue forms around it and the fluid is absorbed. Tube shunts are especially useful for advanced glaucoma, eyes that have had previous surgery, a scarred conjunctiva, and some secondary glaucomas, and they don’t rely on a bleb under the conjunctiva the way trabeculectomy does. The tube is usually covered with a thin patch graft to protect it.
Ahmed valve (the tube shunt Dr. Jones mainly uses)
The Ahmed valve has a built-in valve that limits how fast fluid can leave the eye, which helps protect against very low pressure early after surgery. It’s a reliable, widely used device, and it’s the tube shunt Dr. Jones mainly performs. In the first weeks to months, the pressure can temporarily rise as the tissue capsule forms around the plate, and some patients need drops during this time.
Baerveldt implant (used when it’s the better choice)
The Baerveldt implant has no valve and a larger plate. The tube is temporarily restricted until the eye has healed, to prevent the pressure from dropping too low early on. In studies, Baerveldt implants have tended to lower pressure more than Ahmed valves, with a different set of risks. Dr. Jones has experience with Baerveldt implants and uses them when they’re the better choice for a patient.
Ahmed vs. Baerveldt
| Ahmed valve | Baerveldt implant | |
|---|---|---|
| Valve? | Yes | No (tube temporarily restricted) |
| Plate size | Smaller | Larger |
| Pressure lowering | Good | Often greater |
| Early low-pressure risk | Lower | Higher, until the tube opens |
| Typical use | Most patients who need a shunt | Patients who need more pressure lowering |
| Dr. Jones | Mainly used | Used when it’s the better choice |
Recovery and follow-up
You’ll use drops as directed, and we’ll see you the day after surgery and at follow-up visits over the first weeks and months to check your pressure and the tube. Because there’s no bleb to maintain, follow-up is often simpler than after trabeculectomy, but you still need regular, lifelong monitoring.
Risks of tube shunts
Possible risks include pressure that’s too low or too high, a tube or plate that becomes exposed, corneal problems (from the tube touching the cornea or from cell loss), double vision from the plate’s position near the eye muscles, infection, bleeding, and the need for additional surgery. As with any surgery, it isn’t possible to list every complication, and no outcome can be guaranteed.
Trabeculectomy vs. tube shunt
| Trabeculectomy | Tube shunt | |
|---|---|---|
| How it drains | To a bleb under the conjunctiva | Through a tube to a plate |
| Pressure lowering | Can reach very low pressures | Effective; may not reach the lowest pressures |
| Depends on a healthy bleb? | Yes | No |
| Follow-up | Frequent early on, with possible adjustments or needling | Regular; often simpler |
| Implant in the eye? | No | Yes |
| Often chosen when | A very low pressure is needed; conjunctiva is healthy | Advanced glaucoma, prior surgery, scarred conjunctiva, some secondary glaucomas |
Neither is better for everyone. In large studies, such as the Tube Versus Trabeculectomy (TVT) study, both lowered pressure effectively with different strengths and complication profiles. Dr. Jones will recommend the option that fits your eye.
How successful is glaucoma surgery?
Trabeculectomy and tube shunts are among the most effective ways to lower eye pressure, and they often control it for years. Success depends on the type of glaucoma, the procedure, and how your eye heals, and it’s usually measured by whether the pressure reaches a target level, with or without drops. Even after a successful surgery:
- Many patients still need some drops
- Some need follow-up procedures, such as needling or a repeat procedure
- Pressure can drift up over time, so you’ll need lifelong monitoring
Dr. Jones will explain what success means for your eye.
Less invasive options
Not every patient needs traditional surgery. Depending on your glaucoma, Dr. Jones may recommend a less invasive option first, such as [SLT or MP-CPC laser treatment], [goniotomy], or a [microstent] such as the Xen Gel Stent, a minimally invasive procedure that drains fluid to a bleb with less tissue disruption. These options may not lower pressure enough for advanced glaucoma, which is when trabeculectomy or a tube shunt becomes the better choice.
A newer option on the horizon. AquaLumen is a newer, implant-free device for minimally invasive filtering surgery. Dr. Jones has completed training for it but hasn’t used it in patients yet, and the published evidence so far is limited to small early studies. We’ll update this page if and when we offer it.
What to expect
Before. We examine your eyes and optic nerve, review your tests (visual fields, OCT), and discuss which procedure is right for you. We’ll tell you what to do about your drops and what the recovery involves.
Surgery day. Surgery is outpatient at the American Surgery Center with IV sedation and a numbed eye by nerve block. Surgery takes approximately 1 hour. You go home the same day with a friend or family member.
After. You’ll use drops as directed, and we’ll see you the day after surgery and frequently over the first weeks and months to check your pressure and healing and to treat any problems early. Your vision may be blurry at first. Call us right away if you notice increasing redness, pain, or a drop in vision.
Cost and insurance
Medicare and most insurance plans generally cover medically necessary glaucoma surgery, and your deductible and copay will apply. Coverage varies by plan, so call us and we’ll check your benefits so there are no surprises. See insurance we accept
Why choose San Antonio Eye & Face Institute
- A glaucoma fellowship-trained surgeon. Dr. Jones completed a clinical glaucoma fellowship at Massachusetts Eye and Ear/Harvard Medical School, and performs trabeculectomy and tube shunt surgery.
Read Dr. Jones’s bio - Experience with both Ahmed and Baerveldt tube shunts, so the device can be matched to your eye.
- A full range of options, from drops and lasers (SLT, MP-CPC) to goniotomy, microstents, and traditional surgery, so we recommend what fits your eyes.
- One team for glaucoma and cataracts, so your care is coordinated.
- Honest recommendations, including when a less invasive option is enough.
- Physician-owned, so you see your doctors from your first exam to your last follow-up.
- Se habla español.
Request a Glaucoma Evaluation
Call (210) 485-1488
Frequently asked questions
What is trabeculectomy? Trabeculectomy is the classic glaucoma filtering surgery. The surgeon creates a small, controlled drainage opening in the wall of the eye under a thin flap of sclera so that fluid can drain to a reservoir under the conjunctiva, called a bleb, where it is absorbed. This lowers eye pressure and has been used for decades for glaucoma that is not controlled with drops or laser.
How is trabeculectomy performed? With IV sedation and a numbed eye, the surgeon creates a thin partial-thickness flap in the sclera, makes a small opening beneath it into the eye, usually applies an anti-scarring medication, and closes the flap with fine sutures that control how much fluid drains. Fluid then collects in a bleb under the conjunctiva.
What are tube shunts? A tube shunt, also called a glaucoma drainage device, is a small tube attached to a plate that is placed on the outside of the eye. The tube carries fluid from inside the eye to the plate, where it collects and is absorbed, lowering eye pressure. Tube shunts are often used for advanced glaucoma, eyes that have had previous surgery, and some secondary glaucomas.
What is the difference between the Ahmed valve and the Baerveldt implant? The Ahmed valve has a built-in valve that limits how fast fluid can leave the eye, which helps protect against very low pressure early on. The Baerveldt implant has no valve and a larger plate, so the tube must be temporarily restricted until the eye heals, and it tends to lower pressure more. Each has its own strengths and risks, and the right choice depends on your eye.
Which tube shunt does Dr. Jones use? Dr. Jones mainly performs Ahmed valves and also has experience with Baerveldt implants when they are the better choice for a patient.
Is trabeculectomy or a tube shunt better? Neither is better for everyone. Both lower eye pressure effectively, with different strengths and risks. Trabeculectomy can reach very low pressures but depends on a healthy bleb and needs close follow-up, while tube shunts are often chosen for advanced glaucoma, previous surgery, or a scarred conjunctiva and do not depend on a bleb. Dr. Jones will recommend the best option for your eye.
Who needs glaucoma filtering surgery or a tube shunt? These surgeries are usually recommended when drops and laser are not controlling eye pressure well enough, when the glaucoma is advanced or progressing, or when a lower pressure is needed than minimally invasive glaucoma surgery can provide. Your doctor will explain which procedure fits your eye.
How successful is glaucoma surgery? Trabeculectomy and tube shunts are among the most effective ways to lower eye pressure and often control it for years, but success varies with the type of glaucoma, the procedure, and how your eye heals. Many patients still need some drops, some need follow-up procedures such as needling, and lifelong monitoring is required.
Can glaucoma surgery restore vision I have lost? No. Glaucoma surgery lowers eye pressure to slow or stop further damage to the optic nerve, but it cannot restore vision that has already been lost.
What is a bleb, and does it need care? A bleb is a small, blister-like area of tissue on the white of the eye, usually hidden under the upper eyelid, where fluid collects and is absorbed. You will have frequent follow-up visits after trabeculectomy so we can monitor the bleb and, if needed, treat it to keep it working, and you should report redness, pain, or vision changes right away.
What are the risks of trabeculectomy? Possible risks include eye pressure that is too low or too high, a leaking or scarred bleb, infection, bleeding, inflammation, cataract formation or progression, blurry vision, and the need for additional procedures or surgery. Serious complications are uncommon, and no outcome can be guaranteed.
What are the risks of tube shunts? Possible risks include eye pressure that is too low or too high, a tube or plate that becomes exposed, corneal problems, double vision from the plate’s position near the eye muscles, infection, bleeding, and the need for additional surgery. Serious complications are uncommon, and no outcome can be guaranteed.
How long is recovery after glaucoma surgery? Most patients recover over several weeks, with frequent follow-up visits early on so we can monitor your pressure and healing. You will use drops as directed and avoid activities your doctor advises against, and your vision may be blurry at first.
Will I still need glaucoma drops after surgery? Many patients need fewer drops, and some can stop them, but some still need medication to reach their target pressure. Your doctor will tell you if and when to reduce your drops, so do not stop any on your own.
Are there less invasive options than trabeculectomy? Yes, for some patients. Minimally invasive glaucoma surgery, such as goniotomy, and minimally invasive bleb procedures, such as the Xen Gel Stent, can lower pressure with less tissue disruption, but they may not lower pressure enough for advanced glaucoma. Your doctor will explain which option fits your eye.
What is AquaLumen? AquaLumen is a newer, implant-free device for minimally invasive filtering surgery. Dr. Jones has completed training for the device but has not yet used it in patients, and published evidence so far is limited to small early studies.
Is glaucoma surgery covered by insurance? Medicare and most insurance plans generally cover medically necessary glaucoma surgery. Coverage varies by plan, so call our office and we will check your benefits.
Who performs glaucoma surgery at your practice? Dr. Relief Jones, III, a glaucoma fellowship-trained ophthalmologist, performs glaucoma surgery at the American Surgery Center.
This page is for general education and isn’t a substitute for an eye exam. Only an eye doctor can tell you whether glaucoma surgery is right for you. Product names are trademarks of their respective owners.