Understanding Glaucoma Surgery: What It Actually Does

All glaucoma surgery works by one of two mechanisms: improving drainage of fluid out of the eye, or reducing production of fluid inside the eye. The goal is always the same, to lower intraocular pressure to a level that protects the optic nerve from further damage.

It is important to understand what surgery does not do: it does not restore vision already lost to glaucoma. Damage to the optic nerve from glaucoma is irreversible. Surgery protects the vision you have. This is why the decision about timing matters — surgery at the right moment in the disease course protects more vision than surgery delayed too long.

Types of Glaucoma Surgery

Trabeculectomy vs MIGS: How the Choice Is Made

Patients and referring doctors frequently ask this question, and the answer is never one-size-fits-all. Both procedures lower intraocular pressure. The difference lies in how much pressure reduction is needed, how much surgical risk is acceptable, and what the patient’s disease looks like over the long term.

MIGS offers a gentler reduction in pressure, typically bringing pressure down by 20–30% from baseline, with a significantly lower risk profile and faster recovery. It is the right choice when modest pressure reduction is sufficient to protect the optic nerve, particularly in mild to moderate disease, and especially when cataract surgery is being done at the same time.

Trabeculectomy offers deeper, more sustained pressure reduction, often 30–50% from baseline, sometimes more, and remains the gold standard when the optic nerve needs pressure brought to very low levels to survive. The trade-off is a more demanding postoperative course and a higher risk of complications that require active management.

The decision between them is not simply about severity. A patient with moderate glaucoma who is young, has a low target pressure, and has decades of disease ahead may be better served by trabeculectomy now rather than MIGS that proves insufficient in five years. An older patient with similar pressure but less lifetime risk may do very well with MIGS combined with cataract surgery and avoid a more complex procedure entirely.

This is precisely why the surgical decision requires a subspecialist assessment, not a formula, but a careful weighing of individual factors including age, disease stage, rate of progression, target pressure, conjunctival health, and the patient’s capacity to manage postoperative follow-up.

If you have been quoted one procedure and are uncertain whether it is the right choice for you, a structured glaucoma second opinion before proceeding is entirely reasonable.

Minimally Invasive Glaucoma Surgery (MIGS)

MIGS is a family of newer surgical procedures that lower intraocular pressure through very small incisions, with a significantly better safety profile than traditional glaucoma surgery. They are typically performed under local anaesthesia, often at the same time as cataract surgery, and recovery is faster.

Who is MIGS suitable for?

MIGS is best suited to patients with mild to moderate glaucoma who need pressure lowered but do not yet need the substantial pressure reduction that trabeculectomy provides. It is particularly valuable in patients who also need cataract surgery — combining both procedures reduces surgical burden, often lowers pressure meaningfully, and can reduce dependence on drops.

MIGS is also appropriate for patients who want to reduce drop burden, who have early disease that is progressing despite maximum tolerated medical therapy, or for whom the risks of trabeculectomy outweigh the benefits at that stage of disease.

How does MIGS work?

Different MIGS procedures work through different mechanisms. Some — like the iStent or Hydrus — improve the eye’s natural drainage pathway by placing a tiny implant to bypass the trabecular meshwork and allow fluid to drain more freely into Schlemm’s canal. Others, like the Kahook Dual Blade or Trabectome, remove part of the trabecular meshwork. The XEN gel stent creates a new drainage pathway into the subconjunctival space, similar in principle to trabeculectomy but through a smaller, less invasive approach.

What MIGS cannot do is achieve the very low pressures that trabeculectomy reliably produces. For patients with advanced glaucoma, significant optic nerve damage, or disease that requires pressure in the low teens or single digits, MIGS is usually insufficient as a standalone procedure.

The combined cataract and MIGS procedure

When a patient has both cataract and glaucoma, combining phacoemulsification (cataract removal) with a MIGS procedure is often the most logical choice. Cataract surgery itself lowers eye pressure modestly in many patients, and adding a MIGS procedure at the same time amplifies this effect — often allowing reduction or elimination of drops post-operatively with a single recovery period.

Selective Laser Trabeculoplasty (SLT)

While not a surgical procedure in the traditional sense, SLT deserves mention here because it sits between drops and surgery in the treatment pathway. It uses a laser applied to the drainage angle to stimulate improved outflow. It is effective as a first-line treatment or adjunct, repeatable, and does not preclude future surgery. For appropriate patients — particularly those with early to moderate open-angle glaucoma — SLT can delay or reduce the need for surgery.

Dr Bhartiya is a glaucoma specialist with extensive experience in risk-stratification and longitudinal glaucoma care, including hundreds of SLT and LPI laser procedures.

Trabeculectomy

Trabeculectomy remains the most effective and most extensively studied glaucoma surgery available. It has been the gold standard surgical procedure for over 50 years and, when performed well and followed up carefully, remains unmatched in its ability to achieve sustained low intraocular pressure.

What does trabeculectomy involve?

The surgery creates a new drainage pathway — a small flap in the wall of the eye (the sclera) through which aqueous fluid can drain from inside the eye to just beneath the conjunctiva, forming a small reservoir called a bleb. Fluid is then gradually absorbed from the bleb, lowering intraocular pressure.

An antifibrotic agent — typically Mitomycin C — is applied during surgery to reduce scarring, which is the main cause of trabeculectomy failure over time. The concentration used, and the duration of application, are carefully calibrated to the individual patient.

Who needs trabeculectomy?

Trabeculectomy is indicated for patients with moderate to advanced glaucoma who need substantial and sustained pressure reduction — pressures that MIGS cannot reliably achieve. It is also the appropriate choice when:

• • Disease is advanced and pressure needs to reach very low levels

• • Prior MIGS has been insufficient

• • Progression is rapid and the optic nerve is at high risk

• • The patient is relatively young with decades of disease ahead

In experienced hands, trabeculectomy achieves pressure reduction of 30–50% from baseline, often eliminating the need for drops entirely, at least in the medium term.

What are the risks of trabeculectomy?

Trabeculectomy is effective, but it is not a simple procedure. The risks include hypotony (pressure that drops too low), bleb-related complications, infection (blebitis or endophthalmitis — rare but serious), cataract formation, and the need for further intervention if the bleb scars over. These risks are why trabeculectomy requires careful patient selection, meticulous surgical technique, and close postoperative follow-up — particularly in the first weeks after surgery.

This is also why surgical experience matters. Trabeculectomy outcomes are directly related to surgeon experience and the quality of postoperative management. A bleb that starts to fail can often be rescued with timely intervention — but only if the surgeon knows what to look for and acts promptly.

Tube Shunt Surgery (Glaucoma Drainage Devices)

For patients in whom trabeculectomy has failed, or is likely to fail, tube shunts — such as the Ahmed Glaucoma Valve or Baerveldt implant — provide an alternative drainage pathway. A small silicone tube is implanted in the eye, connected to a plate placed on the surface of the eye under the conjunctiva. Fluid drains through the tube to the plate, where it is absorbed.

Tube shunts are used in:

• • Refractory glaucoma where prior trabeculectomy has failed

• • Eyes with severe scarring that makes trabeculectomy unlikely to succeed

• • Neovascular glaucoma

• • Eyes that have had multiple previous surgeries

• • Certain complex secondary glaucomas

Tube surgery is longer and more involved than trabeculectomy, but it is a valuable and often vision-saving option for patients with complex disease.

Cyclodestructive Procedures

In cases where other surgical options are not suitable, cyclodestructive procedures are an option. This includes advanced disease with limited visual potential, or patients who are not candidates for incisional surgery. The ciliary body (which produces aqueous fluid) is treated to reduce fluid production. the most commonly used technique is Diode laser cyclophotocoagulation (CPC). It is not a first-choice procedure in eyes with good visual potential, but has an important role in selected cases.

How Is the Right Surgery Chosen?

This is the question patients ask most often, when talking about glaucoma surgery in Gurgaon. The honest answer is that there is no formula. The right surgery depends on:

The severity of glaucoma. Mild disease with modest pressure reduction needed points toward MIGS. Advanced disease requiring very low pressures points toward trabeculectomy. Complex, refractory disease may need a tube.

The patient’s age. A 45-year-old with glaucoma needs a solution that will last decades. A 78-year-old with the same pressure may have very different lifetime risk. Age changes the calculus significantly.

The state of the conjunctiva. Trabeculectomy and tube surgery both require healthy conjunctival tissue. Prior eye surgery, prolonged use of certain drops, or previous failed blebs can compromise this, and must be accounted for in surgical planning.

Whether cataract surgery is also needed. If yes, combining with MIGS is often the most efficient path. If not, the options broaden.

The patient’s ability to comply with postoperative care. Trabeculectomy in particular requires careful follow-up in the first weeks: bleb management, suture lysis, monitoring for hypotony. A patient who cannot attend frequent follow-up appointments in the early postoperative period may be better served by a procedure with a less demanding recovery.

The surgeon’s experience with each procedure. Outcomes in glaucoma surgery are strongly surgeon-dependent. The right surgery performed by an experienced surgeon with careful follow-up is always preferable to a theoretically ideal procedure performed by someone who does it infrequently.

What to Expect: Before, During, and After Surgery

Before Surgery

You will have a detailed preoperative assessment reviewing your glaucoma history, current medications, ocular surface health, and systemic health. The surgical plan, which procedure, whether to combine with cataract surgery, antifibrotic use, and anaesthesia approach, will be discussed fully. You will understand exactly what is planned and why.

Certain glaucoma drops may be continued or adjusted before surgery. Blood thinners may need to be paused in consultation with your physician.

The Day of Surgery

Most glaucoma surgeries are performed under local anaesthesia with sedation, as a day procedure. You will not be admitted overnight in most cases. The surgery itself typically takes between 30 and 60 minutes depending on the procedure. You will need someone to accompany you home.

Immediately After Surgery

The eye will be padded after surgery. Your vision is blurred initially, and the eye may be uncomfortable. This is normal. You will have to use antibiotic and anti-inflammatory drops. These are started immediately, and are essential to the outcome. You may have to continue anti glaucoma eye drops also.

For trabeculectomy patients particularly, the first two to four weeks post-operatively are the most important period. Your doctor monitors eye presssure, bleb appearance, and anterior chamber depth closely. She will also make some ddjustments, including suture lysis or bleb massage, if needed, to optimise outcomes. Missing follow-up appointments in this period is not advisable.

Recovery Timeline

For MIGS combined with cataract surgery, most patients recover within one to two weeks, though drops continue for several weeks.

For trabeculectomy, the functional recovery takes longer, typically four to twelve weeks before vision stabilises and the pressure reaches its longer-term level. The bleb continues to mature over months.

Avoid Strenuous activity, swimming, and rubbing the eyes. This duration is for variable periods depending on the procedure.

Long-Term Follow-Up

Glaucoma surgery is not a cure. It is a pressure-lowering intervention. Your IOP needs to be monitored over the long term. After surgery, regular follow-up continues: OCT, visual fields, and pressure checks to ensure the disease remains stable and to catch any late failure of the surgical intervention early.

Some patients remain completely off drops long-term after trabeculectomy. Others need drops restarted months or years later as the bleb matures or scars. MIGS procedures typically achieve a more modest pressure reduction and many patients continue on reduced medication postoperatively.

Glaucoma Surgery in Gurgaon: What to Look For in a Surgeon

Glaucoma surgery outcomes depend on three things: the right procedure chosen for the right patient, meticulous surgical technique, and careful postoperative management.

For patients considering glaucoma surgery in Gurgaon, the relevant questions to ask are: Has this surgeon performed this specific procedure many times? Do they manage their own postoperative follow-up, or is it handed off? What is their protocol for bleb management after trabeculectomy? What happens if the surgery does not achieve the desired pressure?

Dr Shibal Bhartiya performs the full spectrum of glaucoma surgery in Gurgaon: MIGS, trabeculectomy, tube shunts, and revision surgery for failed prior procedures. She manages all surgical patients through their postoperative course personally and has performed and published on glaucoma surgery outcomes for over two decades.

If you have been told you need glaucoma surgery, or if you are uncertain whether surgery is the right next step, a structured consultation can help. This includes a review of your existing reports, to help you make this decision with clarity.

Frequently Asked Questions

Does glaucoma surgery restore vision?

No. Glaucoma surgery lowers eye pressure to protect the optic nerve from further damage. It does not reverse damage already caused. This is why timing matters, surgery that prevents further loss protects the vision you have.

Is glaucoma surgery painful?

Glaucoma surgery is not painful. Your doctor will choose either topical, local or general anaesthesia. You will experience some discomfort and aching in the first day or two postoperatively. Simple analgesics will help you feel better.

Can glaucoma come back after surgery?

Glaucoma is a lifelong condition. Surgery controls pressure but does not cure the underlying disease. Pressure may rise again over months or years if the surgical drainage pathway scars over, requiring additional intervention. This is why long-term follow-up after surgery is essential.

How long does a trabeculectomy last?

Studies show that trabeculectomy with Mitomycin C achieves adequate pressure control in approximately 70–80% of patients at five years, and in a somewhat lower proportion at ten years. The bleb can be revised if it fails, and additional drops or further surgery can be added if needed.

Can I have glaucoma surgery and cataract surgery at the same time?

Yes, in selected patients. Combined phacoemulsification and MIGS is a well-established approach for patients with mild to moderate glaucoma and concurrent cataract. In patients with more advanced glaucoma, the decision to combine or stage the procedures depends on individual factors. Remember, cataract surgery does not protect you from glaucoma.

What if my prior glaucoma surgery has failed?

Failed blebs can sometimes be rescued with bleb needling and antifibrotics. If not, revision surgery or tube shunt surgery are the next options. This is an area requiring glaucoma specialist expertise, not every glaucoma surgeon manages complex revision cases.

What does glaucoma surgery cost in India?

The cost of glaucoma surgery in India varies significantly depending on the procedure, the hospital, and whether additional procedures such as cataract surgery are being combined. MIGS combined with cataract surgery, trabeculectomy, and tube shunt surgery each have different cost profiles. Within each procedure, factors such as the implant used, antifibrotic agents, anaesthesia type also amke a difference. The length of postoperative follow-up all affect the total cost.

Quoting a cost without a clinical assessment is not meaningful or responsible. The right procedure for your eye is the relevant starting point, and cost follows from that. What matters most is that the surgery chosen is appropriate for your stage of disease. It is performed by a surgeon with subspecialty experience in that specific procedure. Also, a proper follow up, particularly in the critical first weeks after trabeculectomy is mandatory.

To understand what surgery is indicated for your situation and what to expect in terms of process and cost, call +91 88826 38735 to arrange an appointment.

Dr Shibal Bhartiya consults for glaucoma surgery in Gurgaon. For appointments, contact +91 88826 38735. If you are seeking a second opinion before proceeding with surgery, a structured glaucoma second opinion is available.

Read the research articles

This article was written by Dr Shibal Bhartiya, fellowship-trained glaucoma specialist and Mayo Clinic Research Collaborator, Clinical Director at Marengo Asia Hospitals, Gurugram, known for ethical, patient-centred glaucoma care and independent glaucoma second opinions. This article was edited in April 2026.

She has published peer-reviewed research on glaucoma management, examining how treatment decisions should balance medical evidence, patient preferences, and long-term vision outcomes.

As Editor-in-Chief of Clinical and Experimental Vision and Eye Research and Executive Editor of the Journal of Current Glaucoma Practice (Pubmed Indexed, official journal of the International Society of Glaucoma Surgery), Dr Shibal Bhartiya brings editorial and research depth to every clinical decision. Her 200+ publications, including 90+ PubMed-indexed publications and 28 edited textbooks span glaucoma biology, surgical outcomes, health equity, and emerging diagnostics.

Available on Pubmed and Google Scholar

These peer-reviewed articles discussing Glaucoma Surgeries can be accessed on PubMed here, here, here, and here (for MIGS); and here, here, here and here for conventional glaucoma surgeries ( trabeculectomy, NPDS and tubes/ glaucoma shunts)

Consultation Details for Glaucoma Surgery in Gurgaon

www.drshibalbhartiya.com
 +91 88826 38735

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