Ab interno canaloplasty for open-angle glaucoma

Evidence-based recommendations on ab interno canaloplasty for open-angle glaucoma. This involves widening the channel that drains fluid from the eye. The aim is to reduce pressure in the eye.

# Recommendations
Evidence on the safety of ab interno canaloplasty for open-angle glaucoma shows no major safety concerns. Evidence on the efficacy is limited in quality and quantity, particularly in the long term. Therefore, this procedure should only be used with special arrangements for clinical governance, consent, and audit or research. Find out what special arrangements mean on the NICE interventional procedures guidance page.
Clinicians wanting to do ab interno canaloplasty for open-angle glaucoma should:
Inform the clinical governance leads in their healthcare organisation.
Give people (and their families and carers, as appropriate) clear information to support shared decision making, including NICE's information for the public.
Ensure that people (and their families and carers, as appropriate) understand the procedure's safety and efficacy, and any uncertainties about these.
Audit and review clinical outcomes of everyone having the procedure. The main efficacy and safety outcomes identified in this guidance can be entered into NICE's interventional procedure outcomes audit tool (for use at local discretion).
Enter details about everyone having ab interno canaloplasty for open-angle glaucoma onto a suitable registry and review local clinical outcomes.
Discuss the outcomes of the procedure during their annual appraisal to reflect, learn and improve.
Healthcare organisations should:
Ensure systems are in place that support clinicians to collect and report data on outcomes and safety for everyone having this procedure.
Regularly review data on outcomes and safety for this procedure.
Patient selection and treatment should be done by glaucoma specialists with training and experience in the technique.
Report any problems with a medical device using the Medicines and Healthcare products Regulatory Agency's Yellow Card Scheme.
Further research should report:
details of patient selection, including concurrent procedures, severity of glaucoma and concomitant therapy
long-term efficacy and safety outcomes.# The condition, current treatments and procedure

# The condition
Glaucoma is usually a chronic condition that is typically associated with raised intraocular pressure (IOP). The most common type of glaucoma in the UK is primary open-angle glaucoma. It leads to progressive damage to the optic nerve. Early stages are usually asymptomatic. But, as the condition progresses, it can cause visual impairment and, if untreated, blindness.
In the healthy eye, aqueous humor drains through the trabecular meshwork (into Schlemm's canal) and through the uveoscleral outflow pathway. In glaucoma, this drainage becomes impaired, either from resistance in the trabecular meshwork pathway (primary open-angle glaucoma) or from obstruction by the iris (primary closed-angle glaucoma).

# Current treatments
Treatment usually involves eye drops containing medicines that either reduce the production of aqueous humor or increase its drainage. Surgical procedures such as trabeculectomy, deep sclerectomy, trabeculotomy, stenting, canaloplasty or laser trabeculoplasty may be used.

# The procedure
Ab interno canaloplasty aims to reduce IOP by improving the drainage of aqueous fluid from the eye in people with open-angle glaucoma. It is usually done under local anaesthesia, but general anaesthesia can be used. Unlike traditional (ab externo) canaloplasty, which is done by cutting through the conjunctiva and sclera, ab interno canaloplasty uses an internal approach through a clear corneal or limbal incision. A microcatheter is introduced into the canal through a small opening in the trabecular meshwork and advanced around its entire circumference. As the catheter tip is withdrawn, viscoelastic fluid is injected into the canal to dilate it. The microcatheter is then removed. The viscoelastic fluid disperses down the collector channels of the eye within 2 to 3 days. The aim is to permanently dilate the canal to allow increased drainage of aqueous humor from the eye and thereby lower IOP. Some devices allow canaloplasty to be done sequentially with trabeculotomy as part of a single operation. Canaloplasty is often done concurrently with phacoemulsification (cataract surgery).