Canaloplasty for Glaucoma: Restoring Natural Drainage to Protect Your Sight
What Is Canaloplasty and How Does It Work
Canaloplasty is a surgical procedure that targets the root cause of elevated eye pressure in many glaucoma patients. Rather than creating a new drainage pathway, it works to restore and support the eye's existing one.
Your eye constantly produces a clear fluid called aqueous humor, which normally drains through a small channel called Schlemm's canal. In glaucoma, this canal can become narrow or blocked, causing fluid to back up and eye pressure to rise. When pressure stays elevated over time, it can damage the optic nerve and gradually steal your vision.
Canaloplasty addresses this problem by threading a tiny flexible tube around the full circumference of Schlemm's canal to stretch it open. A small support thread, called a suture, is then placed inside the canal to keep it expanded over time. This allows fluid to drain more freely and brings eye pressure down to a safer level.
There are two ways to perform canaloplasty, and your eye doctor will choose the one that best fits your anatomy and your goals.
- Ab-externo canaloplasty is the traditional approach, where the surgeon makes a small opening in the white of the eye to access the canal from outside and place the support thread
- Ab-interno canaloplasty is a less invasive approach performed through a tiny incision in the cornea, working from inside the eye without placing a support thread
Ab-interno canaloplasty is considered a form of MIGS, which stands for minimally invasive glaucoma surgery. Some ab-interno techniques also include small cuts in the drainage tissue to further improve fluid outflow.
Your eye doctor may recommend canaloplasty if your glaucoma is not responding well enough to drops, or if side effects from multiple medications have become difficult to manage. It is most effective for primary open-angle glaucoma, the most common form, where the drainage angle is structurally open but not functioning efficiently. Canaloplasty is generally not appropriate for glaucoma types that involve active inflammation, fragile or abnormal blood vessels in the drainage angle, or significant scarring of the drainage structures.
Older glaucoma surgeries like trabeculectomy and tube shunt procedures work by creating an entirely new pathway for fluid to exit the eye. While those approaches can achieve very low pressures, they carry higher risks of infection, prolonged low pressure, and scarring. Canaloplasty works within the eye's existing anatomy, which generally means a lower risk profile, though it may not achieve the same degree of pressure reduction in patients with advanced or complex glaucoma.
The Canaloplasty Procedure Step by Step
Understanding what to expect before, during, and immediately after surgery can help ease any anxiety and prepare you for a smoother recovery. Here is what the process typically looks like.
Before scheduling surgery, your eye doctor will perform a thorough eye examination including measurement of your eye pressure, imaging of your optic nerve, and evaluation of your drainage angle. You may be asked to pause certain glaucoma drops or blood-thinning medications in the days leading up to the procedure, and you will receive specific instructions about which ones to continue. Plan to have someone drive you home on the day of surgery, as canaloplasty is performed on an outpatient basis.
The surgery is performed using local anesthetic to numb your eye, often combined with sedation so you remain comfortable and relaxed throughout. For the ab-externo approach, the surgeon creates a shallow opening in the outer layer of the eye, threads a tiny illuminated catheter around the full length of Schlemm's canal, and injects a gel to dilate the canal before placing the support suture. For the ab-interno approach, the surgeon enters through a small corneal incision and uses a specialized device to widen the canal from the inside, sometimes combined with small cuts in the adjacent drainage tissue. Most procedures take between 30 and 60 minutes, though this varies depending on which technique is used and whether cataract surgery is performed at the same time.
Many patients who have glaucoma also have cataracts, and it is common to address both conditions in a single procedure. Combining cataract removal with canaloplasty offers the convenience of one surgery and recovery period, and research suggests that removing the lens can itself contribute to a modest reduction in eye pressure, which complements the effects of canaloplasty. Our surgeons will discuss whether this combined approach is appropriate for your situation.
Recovery After Canaloplasty
Recovery from canaloplasty is generally well tolerated, though the timeline varies depending on which technique was used and how each individual heals. Knowing what is normal and what to watch for helps you recover safely.
After surgery, your eye will be protected with a shield. Mild discomfort, redness, light sensitivity, and blurred vision are common in the first few days and typically improve steadily over the following weeks. Your eye doctor will prescribe antibiotic and anti-inflammatory eye drops to prevent infection and reduce swelling. Most patients can return to light, everyday activities within a few days, but heavy lifting, straining, and swimming should be avoided for several weeks to protect the healing eye.
You will have several follow-up appointments in the weeks and months after surgery. At each visit, your eye doctor will measure your pressure, assess how your eye is healing, and adjust your glaucoma medications as needed. Attending every scheduled visit is important, since eye pressure can fluctuate during the healing process and adjustments may be needed to keep it in a safe range.
While serious complications are uncommon, you should contact your eye doctor right away if you experience any of the following after surgery.
- Sudden or worsening vision loss
- Severe eye pain that does not improve
- Increasing redness or discharge from the eye
- New or worsening flashes of light or floating spots
These symptoms are not typical parts of recovery and may indicate a complication that requires immediate evaluation.
Outcomes, Success Rates, and Risks
Like all surgical procedures, canaloplasty carries both potential benefits and risks. Understanding both helps you make an informed decision together with your eye doctor.
Studies show that canaloplasty can reduce eye pressure by roughly 20 to 40 percent from pre-surgical levels, though individual results vary. The ab-externo approach with a support suture has been shown in some studies to provide slightly stronger long-term pressure reduction compared to ab-interno methods. Your starting pressure, type of glaucoma, and overall drainage anatomy all influence how much reduction you can expect.
Many patients are able to reduce the number of glaucoma drops they use after canaloplasty, though most will still need at least some medication to maintain safe pressure levels. Some patients may eventually need additional laser treatment or a different surgery if pressure control is not fully adequate. Glaucoma is a lifelong condition, and ongoing monitoring remains essential even after successful surgery.
Patients with mild to moderate glaucoma generally experience better outcomes than those with advanced disease. Other factors that can affect results include the health and flexibility of the drainage canal, the presence of prior eye surgery, and how closely post-operative instructions are followed. Your eye doctor will review your specific situation carefully before recommending this procedure.
Common temporary side effects include mild discomfort, redness, and blurred vision, which usually resolve within a few weeks. Less common but more serious complications can include infection inside the eye, bleeding, damage to the cornea or natural lens, and persistent low eye pressure. Vision loss is a rare but possible risk with any intraocular surgery. Your surgeon will walk through all relevant risks with you during your consultation so you can weigh them against the potential benefits.
Frequently Asked Questions
These answers address practical questions that go beyond the basics of how canaloplasty works, helping you make sense of what the procedure means for your day-to-day life and your long-term glaucoma management.
During the surgery, your eye is fully numbed so most patients feel little to no pain. Afterward, a mild scratchy or achy sensation is common and usually manageable with over-the-counter pain relievers. Severe or worsening pain after surgery is not normal and should be reported to your eye doctor promptly, as it may signal a complication that needs to be evaluated quickly.
Pressure often begins to decline within the first few weeks after canaloplasty, but the full effect can take several months to develop as the eye heals and the drainage canal stabilizes. This is one reason why follow-up visits are so important during the recovery period. Your eye doctor may temporarily adjust your glaucoma drops during this time to manage any fluctuations in pressure.
That depends on how much pressure reduction the surgery achieves and what your target pressure is to protect your optic nerve. Some patients can reduce the number of drops significantly, while others may still need one or more medications. The goal is not necessarily to eliminate drops entirely but to achieve safe, stable pressure with the least amount of treatment burden. Your eye doctor will reassess your medication needs at each follow-up.
Canaloplasty does not close the door on other treatments. If additional pressure reduction is needed, options such as trabeculectomy or tube shunt surgery are still available, and in some cases a second canaloplasty may be considered. Because canaloplasty works within the natural anatomy of the eye and does not disrupt the outer eye wall the way traditional filtering surgeries do, it generally does not make subsequent procedures more complicated.
Canaloplasty is typically covered by most major insurance plans, including Medicare, when it is medically indicated for the treatment of glaucoma. Coverage details, including deductibles and out-of-pocket costs, vary by plan. We encourage you to contact your insurance provider directly before your procedure to understand your specific benefits, and our team can assist with authorization and documentation when needed.
Prior eye surgery does not automatically rule out canaloplasty, but it does factor into the decision. Surgeries that involved the drainage area, such as a previous trabeculectomy or trabecular bypass procedure, may affect the anatomy of Schlemm's canal in ways that reduce the likelihood of a successful outcome. Your eye doctor will carefully review your full surgical history and examine your drainage structures before determining whether canaloplasty is a good option for you.
Expert Glaucoma Care at Rhode Island Eye Institute
Our team at Rhode Island Eye Institute includes fellowship-trained glaucoma surgeons with advanced expertise in both surgical and medical glaucoma management. We bring together specialized diagnostics, a full range of surgical options, and personalized care to help you protect your vision for the long term. If you have been told that drops alone are not enough, we encourage you to schedule a consultation and explore whether canaloplasty or another approach is right for you.