Glaucoma microstents in San Antonio
Tiny implants that help lower eye pressure, and how to choose among them
There are several types of microstents available to reduce eye pressure in glaucoma, including the iStent, Hydrus, Xen Gel Stent, and AlloFlo. Each offers a potential way to manage eye pressure with less risk and a quicker recovery than traditional glaucoma surgery, but none is right for everyone. At San Antonio Eye & Face Institute, Dr. Relief Jones, III, a glaucoma fellowship-trained ophthalmologist, currently uses the Xen Gel Stent most often, and he’ll help you decide whether a microstent, another procedure, or no surgery at all is the best choice for your eyes.
Reviewed by Dr. Relief Jones, III, M.D. · Last updated: October 9, 2026
Which stents does Dr. Jones perform?
| Microstent | Status at our practice |
|---|---|
| Xen Gel Stent | Performed. The microstent Dr. Jones uses most often |
| iStent | Described below for information. Dr. Jones no longer performs it |
| Hydrus Microstent | Described below for information. Dr. Jones no longer performs it |
| AlloFlo | Described below for information. Dr. Jones hasn’t performed it yet but plans to add it |
Looking for an angle-based option like iStent or Hydrus? Dr. Jones performs goniotomy, which can be done during cataract surgery or on its own. Dr. Jones has used the iStent and Hydrus Microstent in the past, but has personally found the most consistent results with goniotomy (increased flow into the eye’s natural drainage canal – Schlemm’s canal).
What are glaucoma microstents?
Glaucoma damages the optic nerve, and high eye pressure is the main risk factor we can treat. Fluid (aqueous humor) is constantly made inside the eye and must drain out. When the drainage system doesn’t work well, pressure builds. Microstents are tiny devices placed in the eye through a very small incision to create or improve a drainage path, which lowers the pressure. They’re part of minimally invasive glaucoma surgery (MIGS): they generally carry lower risk and recover faster than traditional surgeries such as trabeculectomy and tube shunts.
Microstents differ in where they send the fluid:
- Into the eye’s natural drainage canal (Schlemm’s canal): iStent and Hydrus
- Under the conjunctiva, forming a small reservoir (a bleb): Xen Gel Stent
- Into another natural drainage route (the uveoscleral pathway): AlloFlo
How they compare
| Xen Gel Stent | iStent | Hydrus | AlloFlo | |
|---|---|---|---|---|
| What it is | Soft, flexible gelatin-based tube | Tiny titanium stent | Small flexible scaffold | Donated human sclera |
| Where fluid drains | Under the conjunctiva (a bleb) | Schlemm’s canal | Schlemm’s canal | Uveoscleral pathway |
| Pressure lowering | Generally greater – 30% to 50% reduction (~54–75% of patients hit a ≥20% reduction) |
Modest – 15% to 30% reduction (~40% of patients hit a ≥20% reduction) |
Modest to moderate – 15% to 30% reduction (~60% of patients hit a ≥20% reduction) |
Generally greater – 30% to 40% reduction (~71–74% of patients hit a ≥20% reduction) |
| Usually done | With cataract surgery or alone | With cataract surgery | With cataract surgery | With cataract surgery |
| Bleb? | Yes | No | No | No |
| Follow-up | More frequent, to monitor the bleb | Routine | Routine | Routine |
| Typical patient | Moderate to advanced, or refractory glaucoma | Mild to moderate glaucoma; usually performed alongside cataract surgery | Mild to moderate glaucoma; usually performed alongside cataract surgery | Mild to moderate glaucoma; often used if Schlemm’s canal surgery has already failed |
| Maker | AbbVie (Allergan) | Glaukos | Alcon | lantrek |
| Dr. Jones | Performs | No longer performs | No longer performs | Plans to add |
Xen Gel Stent (what Dr. Jones uses most)
What is it?
The Xen Gel Stent is a soft, flexible tube about 6 millimeters long, made of a gelatin-based material. It’s placed through a small incision in the cornea and creates a new pathway for fluid to drain from inside the eye to a small reservoir under the conjunctiva, called a bleb, where the fluid is absorbed. Because it creates a new drainage route instead of improving the eye’s natural one, it can lower eye pressure more than stents that work through the natural drainage canal. The gelatin is made from pig (porcine) collagen. If this matters to you for dietary, religious, or allergy reasons, tell us.
Who is it for?
The Xen Gel Stent is used for open-angle glaucoma that isn’t well controlled with medications, including cases where previous surgery hasn’t worked, and when more pressure lowering is needed than angle-based procedures (such as goniotomy, iStent, or Hydrus) can provide. Dr. Jones typically performs Xen Gel Stents as a stand alone procedure.
What to expect
Before. We examine your eyes and optic nerve, check your drainage angle, and review your tests. We’ll explain what a bleb is and what follow-up involves, since the stent works best when the bleb is monitored.
Surgery day. The procedure is performed at the American Surgery Center with IV sedation and a numbed eye. Dr. Jones places the stent using a minimally-invasive, external approach. An anti-scarring medicine called mitomycin-C is used during the surgery to keep the bleb open. 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 your bleb. Occasionally, a bleb that scars or stops working needs a small in-office procedure called needling to restore the flow. You may still need some glaucoma drops, and regular check-ups continue for life.
Risks
Possible risks include a leaking bleb, eye pressure that’s too low or too high, scarring that closes the bleb, infection (bleb-related infections are uncommon but serious and need prompt treatment), bleeding, movement or exposure of the stent, blurry vision, and the need for additional treatment or surgery. As with any surgery, it isn’t possible to list every complication, and no outcome can be guaranteed. Call us right away if you notice increasing redness, pain, or a drop in vision.
iStent (not currently performed by Dr. Jones)
The iStent is a tiny titanium device placed through the trabecular meshwork into Schlemm’s canal, the eye’s natural drainage channel, to improve fluid flow and lower pressure. Different versions exist; some use more than one stent. It’s usually placed during cataract surgery in patients with mild to moderate open-angle glaucoma, and newer versions may be approved for use on their own. It has no bleb and a low rate of serious complications. Dr. Jones no longer performs this procedure.
Hydrus Microstent (not currently performed by Dr. Jones)
The Hydrus Microstent is a small, flexible scaffold, made of a metal alloy, placed in Schlemm’s canal. It holds the canal open over a longer stretch than a single small stent, improving the eye’s natural drainage. It’s typically placed during cataract surgery in patients with mild to moderate open-angle glaucoma, and, like the iStent, it has no bleb. Dr. Jones no longer performs this procedure.
AlloFlo (not yet performed by Dr. Jones)
AlloFlo is a newer glaucoma implant made from donated human tissue (an allograft) that creates another route for fluid to leave the eye, through the uveoscleral pathway, which differs from the drainage routes used by the other stents. It is utilized for patients with moderate-to-advanced primary open-angle glaucoma whose eye pressure is not adequately controlled by medications, laser treatments, or other minimally-invasive glaucoma surgeries. Dr. Jones hasn’t performed AlloFlo cases yet, but plans to add it to the procedures he performs.
Which option is right for you?
The best glaucoma procedure depends on several things:
- How advanced your glaucoma is and how low your pressure needs to be
- The type of glaucoma, and whether your drainage angle is open
- Whether you also have a cataract and want to treat both at once
- Previous glaucoma surgery or laser treatment
- How you feel about a bleb and more frequent follow-up visits
- Allergies, dietary or religious considerations, and your overall health
Dr. Jones will tell you honestly which approach he recommends. For some patients, that’s a stent; for others it’s goniotomy, laser, or traditional surgery, and sometimes no surgery yet. As a rough guide:
| If you have… | Options Dr. Jones may discuss |
|---|---|
| Mild to moderate open-angle glaucoma and a cataract | Goniotomy with cataract surgery; SLT |
| Moderate glaucoma needing more pressure lowering, or prior surgery that failed | Xen Gel Stent; other surgery |
| Advanced glaucoma needing a very low pressure | Trabeculectomy or tube shunt; MP-CPC |
Goniotomy · SLT and MP-CPC laser treatment · Glaucoma surgery options
Cost and insurance
Medicare and most insurance plans generally cover minimally invasive glaucoma surgery when it’s medically necessary, including when it’s performed with cataract surgery. 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 the Xen Gel Stent as well as goniotomy and other glaucoma surgery. Read Dr. Jones’s bio
- A full range of options, from drops and lasers (SLT, MP-CPC) to goniotomy, stents, and traditional surgery, so we recommend what fits your eyes, not just one device.
- One team for glaucoma and cataracts, so your care is coordinated.
- Honest recommendations. If a different procedure is better for you, we’ll say so.
- 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 a glaucoma microstent? A glaucoma microstent is a tiny device implanted in the eye to lower eye pressure by improving how fluid drains out of the eye. Microstents are part of minimally invasive glaucoma surgery (MIGS) and are placed through a very small incision.
What types of glaucoma microstents are available? The main options are the iStent, the Hydrus Microstent, the Xen Gel Stent, and AlloFlo. They differ in where they drain fluid, how much they lower eye pressure, and the patients they suit best.
Which microstent does Dr. Jones use? Dr. Jones uses the Xen Gel Stent most often. He no longer performs iStent or Hydrus procedures, and he has not yet performed AlloFlo cases but plans to add it to his procedures.
How does the Xen Gel Stent work? The Xen Gel Stent is a soft, flexible tube about 6 millimeters long that is placed through a small incision in the cornea. It creates a new pathway for fluid to drain from inside the eye to a small reservoir under the conjunctiva, called a bleb, where the fluid is absorbed.
Who is a candidate for the Xen Gel Stent? The Xen Gel Stent is used for open-angle glaucoma that is not well controlled with medications, including cases where previous surgery has not worked, and when more pressure lowering is needed than angle-based procedures can provide. Your exam will show whether it is right for you.
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 surgery 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 the Xen Gel Stent? Possible risks include a leaking bleb, eye pressure that is too low or too high, scarring that closes the bleb, infection, bleeding, movement or exposure of the stent, and the need for additional treatment or surgery. Serious problems are uncommon, and your surgeon will review your personal risks with you.
What is the iStent? The iStent is a tiny titanium device placed through the trabecular meshwork into Schlemm’s canal to improve the eye’s natural drainage. It is usually placed during cataract surgery in patients with mild to moderate open-angle glaucoma. Dr. Jones no longer performs this procedure.
What is the Hydrus Microstent? The Hydrus Microstent is a small, flexible scaffold placed in Schlemm’s canal that holds the canal open and improves drainage. It is typically placed during cataract surgery in patients with mild to moderate open-angle glaucoma. Dr. Jones no longer performs this procedure.
What is AlloFlo? AlloFlo is a newer glaucoma implant that creates another route for fluid to leave the eye. Dr. Jones does not offer it yet but plans to add it to the procedures he performs.
Can I get an iStent or Hydrus at your practice? Dr. Jones no longer performs these procedures. For an angle-based option, he performs goniotomy, which can also be done during cataract surgery, and he can recommend the best procedure for your eyes.
Can a microstent be combined with cataract surgery? Often, yes. Microstents are frequently placed during cataract surgery, which lets you treat both conditions in one operation. Some, such as the Xen Gel Stent, can also be performed on their own.
Will I still need glaucoma drops after a microstent? Many patients need fewer drops, and some can stop them, but a microstent does not work for everyone and is not a cure. Your doctor will tell you if and when to reduce your drops, so do not stop any on your own.
Are glaucoma microstents covered by insurance? Medicare and most insurance plans generally cover minimally invasive glaucoma surgery when it is medically necessary, including when it is performed with cataract surgery. Coverage varies by plan, so call our office and we will check your benefits.
Who performs microstent surgery at your practice? Dr. Relief Jones, III, a glaucoma fellowship-trained ophthalmologist, performs the Xen Gel Stent 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 a microstent is right for you. Product names are trademarks of their respective owners.