Canaloplasty is an advanced surgical treatment for glaucoma. It uses breakthrough microcatheter technology to enlarge your eye’s natural drainage system, similar to angioplasty. Canaloplasty is a restorative treatment. Unlike trabeculectomy, which bypasses the eye’s natural drainage channels, Canaloplasty restores the natural outflow pathways in order to reduce elevated intraocular pressure (IOP). It is a 'non-penetrating' glaucoma surgery that does not require the creation of a permanent hole in the eye, so does not result in a 'bleb' (blister). Canaloplasty has an excellent safety profile with minimal post-operative follow-up and faster recovery time.
Most glaucoma treatments fail to completely address the natural outflow system and may even disturb the natural outflow function. Unlike traditional glaucoma surgeries (trabeculectomy and tube shunts), which bypass the natural outflow system, Canaloplasty works by restoring the natural ocular outflow function in four key steps:
The trabecular meshwork is more permeable due to microperforations caused by injection of viscoelastic and and it is stretched by a circumferential suture which holds the meshwork open to allow the fluid to pass through.
The canal into which the fluid drains, known as Schlemm’s canal, is dilated by injection of a visco-elastic substance so that the flow is enhanced.
The dilation of the canal also opens up the collector channels which transport the fluid into the circulation system.
An additional fluid reservoir is created within the ocular wall. This reservoir can be stimulated to release more fluid if necessary in the longer term.
After the surgery, you may feel some slight irritation under the eyelid until the sutures have fully resorbed. You may also see some bleeding in the front of the eye. This is usually a sign that the connection between the circulatory system and the aqueous outflow has been restored and that the surgery has been successful. Your surgeon will schedule one or more post-operative visits to ensure that everything is going smoothly and to check your IOP, and will prescribe drops to soothe your eye and prevent infection. You can resume normal, day-to-day activities, such as watching TV, immediately following treatment.
It is important to remember that managing glaucoma is a lifelong process: even after Canaloplasty and other glaucoma treatments, you will need to continue to visit your ophthalmologist every three to six months.
One of the key advantages of Canaloplasty is its high safety profile. It is associated with significantly fewer risks, both in number and severity, than traditional glaucoma surgeries. It is important to note, however, that all surgeries have risks associated with them.
The most common risks of Canaloplasty are:
Bleeding in the Eye
Almost 30% of people who have Canaloplasty have some bleeding in the front of the eye. This bleeding (called a hyphema or microhyphema) resolves with time and rarely causes any permanent reduction in vision. It is a good prognosis for surgery because it is a sign that contact has been established with the blood circulation system.
Intraocular Pressure 'Spikes'
About 5% of patients will record a post-surgery IOP that is higher than it was before surgery. This is almost always transient and of no consequence.
The Formation of a Bleb
Approximately 6% of patients will experience the formation of a bleb (blister) on the surface of the eye in the area of the incision. It is important to note that with trabeculectomy, the formation of a (stable) bleb is necessary for success and is a necessary side effect of the surgery. With Canaloplasty, it is not a desired outcome but it rarely limits the effectiveness of the surgery.
Descemet’s Membrane Separation
In approximately 3% of patients the viscoelastic can dissect beneath Descemet’s Membrane (the thin film on the back of the cornea) and corneal stroma. In the majority of cases this condition will resolve on its own. If it does not improve spontaneously, your surgeon may inject a gas bubble into your eye to press this membrane back against the cornea.
Hypotony (IOP too low)
In some cases, IOP may drop too low – below 5mmHg – following the procedure. This condition is rare with Canaloplasty and only one person in two hundred (0.5%) would be expected to have prolonged hypotony. However at least one out of every ten patients (10%) is likely to experience hypotony following trabeculectomy.
It is necessary to first undergo an ophthalmic examination in order to determine your eligibility for Canaloplasty.
Canaloplasty is indicated for the reduction of elevated IOP in open-angle glaucoma (OAG) patients, including pigmentary glaucoma (PG), pseudoexfoliation glaucoma (PXF), normal tension glaucoma (NTG) and juvenile glaucoma. While it can be performed across the entire glaucoma treatment spectrum, it is particularly well suited to patients who have difficulty administering eye drops, or for whom medications or laser treatment are no longer effective. It is also a good option for patients who are reluctant to undergo the more invasive trabeculectomy surgery, which is often reserved for the end-stage of the disease. Trabeculectomy can severely limit your ability to participate in certain sports. No such limitation exists with Canaloplasty. Once healed, patients who have had Canaloplasty are able to return to their previous active lifestyles without restriction or limitation.