Microinvasive subconjunctival insertion of a trans-scleral gelatin stent for primary open-angle glaucoma

Evidence-based recommendations on microinvasive subconjunctival insertion of a trans-scleral gelatin stent for primary open-angle glaucoma in adults. This involves putting a tiny gelatin tube (stent) under the skin at the base of the eye to create a new drainage channel for excess fluid.

# Recommendations
Evidence on the safety and efficacy of microinvasive subconjunctival insertion of a trans-scleral gelatin stent for primary open-angle glaucoma is limited in quantity and quality. 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 wishing to do microinvasive subconjunctival insertion of a trans-scleral gelatin stent for primary open-angle glaucoma should:
Inform the clinical governance leads in their NHS trusts.
Ensure that patients understand the uncertainty about the procedure's safety and efficacy and provide them with clear information to support shared decision-making. In addition, the use of NICE's information for the public is recommended.
Audit and review clinical outcomes of all patients having microinvasive subconjunctival insertion of a trans-scleral gelatin stent for primary open-angle glaucoma. NICE has identified relevant audit criteria and has developed NICE's interventional procedure outcomes audit tool.
NICE encourages further research into microinvasive subconjunctival insertion of a trans-scleral gelatin stent for primary open-angle glaucoma, including randomised studies. Further research should include details of patient selection and long-term outcomes.# The condition, current treatments and procedure

# The condition
Open-angle glaucoma is a chronic condition associated with increased intraocular pressure, which leads to progressive damage to the optic nerve. Early stages are usually asymptomatic but as the condition progresses it causes visual impairment and, if untreated, blindness.

# Current treatments
Treatment is usually eye drops containing drugs that either reduce the production of aqueous humor or increase its drainage. Surgical procedures such as trabeculectomy, inserting drainage tubes, deep sclerectomy, viscocanalostomy or laser trabeculoplasty may also be used.

# The procedure
Microinvasive insertion of a trans-scleral gelatin stent via the ab interno approach (placed surgically from the anterior chamber, outwards to the subconjunctival space) for treating open-angle glaucoma is a minimally invasive procedure. It involves implanting a gelatin stent, a collagen-derived drainage device, to reduce intraocular pressure. The collagen is derived from animal sources. The procedure creates an artificial bypass channel and drainage pathway from the anterior chamber into the non-dissected tissue of the subconjunctival space to improve drainage and outflow of aqueous humor.
This procedure can be done at the same time as phacoemulsification and intraocular lens insertion for treating cataracts.
Under local or topical anaesthesia, a small incision is made in the cornea, and the anterior chamber is filled with viscoelastic. A preloaded implant injector is then advanced through the same corneal incision and directed towards the scleral spur. The injector needle is directed through the sclera to emerge under the conjunctiva, approximately 2 mm to 3 mm behind the limbus. The soft and permanent gelatin stent is then injected, to traverse the anterior chamber, sclera and conjunctival space. After placement is checked (using a gonioscopy mirror) the viscoelastic is exchanged for a balanced salt solution and the injector is withdrawn. The corneal incision is usually self-sealing but is sometimes sutured. Subconjunctival injection of mitomycinC may be done during the procedure.