Interventional procedure consultation document

Trabeculotomy ab interno for open-angle glaucoma

Treating glaucoma by removing a small strip of tissue to reduce pressure within the eye

Primary open-angle glaucoma is a condition associated with a long-term increase of pressure within the eye. It may gradually lead to permanent loss of sight because of damage to the nerve that connects the eye to the brain (optic nerve).

This procedure uses a specifically designed surgical instrument to remove a portion of tissue with the aim of improving the eye’s drainage pathway, leading to a reduction in pressure within the eye.

The National Institute for Health and Clinical Excellence (NICE) is examining trabeculoctomy ab interno for open-angle glaucoma and will publish guidance on its safety and efficacy to the NHS in England, Wales, Scotland and Northern Ireland. NICE’s Interventional Procedures Advisory Committee has considered the available evidence and the views of Specialist Advisers, who are consultants with knowledge of the procedure. The Advisory Committee has made provisional recommendations about trabeculoctomy ab interno for open-angle glaucoma.

This document summarises the procedure and sets out the provisional recommendations made by the Advisory Committee. It has been prepared for public consultation. The Advisory Committee particularly welcomes:

• comments on the provisional recommendations
• the identification of factual inaccuracies
• additional relevant evidence, with bibliographic references where possible.

Note that this document is not NICE’s formal guidance on this procedure. The recommendations are provisional and may change after consultation.

The process that NICE will follow after the consultation period ends is as follows.

• The Advisory Committee will meet again to consider the original evidence and its provisional recommendations in the light of the comments received during consultation.
• The Advisory Committee will then prepare draft guidance which will be the basis for NICE’s guidance on the use of the procedure in the NHS in England, Wales, Scotland and Northern Ireland.

For further details, see the Interventional Procedures Programme manual, which is available from the NICE website (www.nice.org.uk/ipprogrammemanual).

NICE is committed to promoting through its guidance race and disability equality and equality between men and women, and to eliminating all forms of discrimination. One of the ways we do this is by trying to involve as wide a range of people and interest groups as possible in the development of our guidance on interventional procedures. In particular, we aim to encourage people and organisations from groups in the population who might not normally comment on our guidance to do so.

In order to help us promote equality through our guidance we would be grateful if you could consider the following question:

Are there any issues that require special attention in light of NICE’s duties to have due regard to the need to eliminate unlawful discrimination and promote equality and foster good relations between people with a characteristic protected by the equalities legislation and others?

Closing date for comments: 21 February 2011

Target date for publication of guidance: May 2011

1   Provisional recommendations

1.1  Current evidence on the safety and efficacy of trabeculoctomy ab interno for open-angle glaucoma is adequate to support the use of this procedure provided that normal arrangements are in place for clinical governance, consent and audit.

1.2  Patient selection should be carried out in units that specialise in glaucoma treatment that can offer a range of treatment options.

1.3  NICE encourages the collection and publication of further data on long-term efficacy.

2   The procedure

2.1  Indications and current treatments

2.1.1  Open-angle glaucoma is a chronic condition associated with elevated intraocular pressure (IOP). Early stages are usually asymptomatic but as the condition progresses it leads to visual impairment and, if untreated, blindness.

2.1.2  Treatment usually involves eye drops containing different pharmacological agents that reduce the production or increase the absorption of aqueous humour. Surgical procedures such as trabeculectomy, deep sclerectomy and viscocanalostomy, or laser trabeculoplasty may also be used.

2.2   Outline of the procedure

2.2.1  Trabeculoctomy ab interno for open-angle glaucoma aims to reduce IOP by removing a portion of the trabecular meshwork to improve drainage of aqueous humour. It avoids the creation of a subconjunctival bleb associated with traditional trabeculectomy.

2.2.2  With the patient under local anaesthesia, a scleral incision is made and viscoelastic is inserted into the anterior chamber. Electrical ablation is used to remove a strip(s) of the trabecular meshwork. A goniolens is used to help this process. The eye is then irrigated and the viscoelastic is aspirated from the anterior chamber. The incision is sutured.

Sections 2.3 and 2.4 describe efficacy and safety outcomes from the published literature that the Committee considered as part of the evidence about this procedure. For more detailed information on the evidence, see the overview, available at www.nice.org.uk/guidance/IP/860/overview

2.3   Efficacy

2.3.1  A case series of 1688 patients reported a reduction in mean IOP from 23.5 mmHg preoperatively to 16.4 mmHg at 5-year follow-up (absolute number of patients reported on at 5 years not stated).

2.3.2  A case series of 304 patients reported procedural success (defined as 20% or greater drop in IOP or decrease in glaucoma medications, without the need for additional medications or glaucoma procedures including laser trabeculectomy) in 78% (83/106) at 6-month follow-up.

2.3.3  A case series of 53 patients reported complete overall success of the procedure (defined as an IOP value of 21 mmHg or less without the use of medication) in 91% of patients at 24-month follow-up (absolute figures not stated). The same study reported a significant reduction in mean IOP from 25.6 mmHg to 15.0 mmHg at 24 months (p < 0.005).

2.3.4  Case series of 1688, 53 and 21 patients reported reductions in the mean number of glaucoma medications used by patients after the procedure - from 3 to 1 at 5-year follow-up; 3 to less than 1 at 24-month follow-up; and 2 to less than 1 at mean follow-up of 25.3 months, respectively.

2.3.5  The case series of 1688 patients reported that 10% (162/1688) of patients required an additional procedure during the 5-year follow-up. This included 96 trabeculectomies (6% of patients), 41 aqueous tube shunts (2%) and 14 repeat ab interno trabeculotomy procedures (1%).

2.3.6  The Specialist Advisers listed the key efficacy outcome as reduction in IOP.

2.4   Safety

2.4.1  The case series of 1688 patients reported an increase in IOP of more than 10 mmHg after the procedure in 6% (96/1688) of patients (follow-up not stated).

2.4.2  The case series of 53 patients reported temporary IOP elevation (not otherwise described) in 23% (12/53) of patients.

2.4.3  The case series of 1688 patients reported hypotony (defined as an IOP of less than 5 mmHg) 1 day after the procedure in 1% (24/1688) of patients (follow-up not stated; not otherwise described).

2.4.4  The case series of 1688 patients reported corneal Descemet’s limited membrane tear in 4 patients (timing of event not stated).

2.4.5  The case series of 53 patients reported moderate cataract with no influence on visual acuity in 11% (6/53) of patients and cataract with a loss of 1 line of visual acuity on the Snellen chart  in 6% (3/53) of patients at 24-month follow-up.

2.4.6  The Specialist Advisers listed adverse events reported in the literature or anecdotally: hyphaema (blood in anterior chamber) and potential damage to the iris and lens (if performed on phakic eyes without concurrent cataract extraction). They considered theoretical adverse events to include trabecular meshwork scarring, which could render the procedure ineffective after 6–12 months.

2.5   Other comments

2.5.1  The Committee noted that compliance with glaucoma medication is often poor and that the usual surgical treatment is trabeculectomy. It seemed plausible that alternative procedures, such as this one, might offer advantages to selected patients. 

2.5.2  The Committee noted concerns about the possibility of failure of the procedure in the long term but was advised that this would not preclude further surgical treatment.

3   Further information

3.1  For related NICE guidance see www.nice.org.uk

Bruce Campbell

Chairman, Interventional Procedures Advisory Committee

January 2011

_{Personal data will not be posted on the NICE website. In accordance with the Data Protection Act names will be anonymised, other than in circumstances where explicit permission has been given.}

_{It is the responsibility of consultees to accurately cite academic work in order that they can be validated.}