Interventional procedures consultation document - implantation of an opaque intraocular lens for intractable double vision

NATIONAL INSTITUTE FOR HEALTH AND CLINICAL EXCELLENCE

 

Interventional Procedure Consultation Document

Implantation of an opaque intraocular lens for intractable double vision

Double vision (also known as diplopia) is seeing two images of a single object instead of one. In this procedure, the clear lens of one eye is removed and replaced with an opaque (non-transparent) lens, with the aim of blocking out one of the two images.

 

The National Institute for Health and Clinical Excellence (NICE) is examining implantation of an opaque intraocular lens for intractable double vision 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 implantation of an opaque intraocular lens for intractable double vision.

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.

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  • The Advisory Committee will then prepare draft guidance which will be the basis for NICE's guidance on the use of the procedure in the NHS in England, Wales, Scotland and Northern Ireland.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 our 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. We also ask consultees to highlight any ways in which draft guidance fails to promote equality or tackle discrimination and give suggestions for how it might be improved.

Closing date for comments:16 December 2008

Target date for publication of guidance: March 2009

 

Note that this document is not the Institute's guidance on this procedure. The recommendations are provisional and may change after consultation.
1 Provisional recommendations
1.1 Implantation of an opaque intraocular lens for intractable double vision is technically similar to standard cataract surgery and is indicated only in highly selected patients. In this context the evidence on safety and efficacy, which is limited to a small number of patients, appears adequate for the procedure to be used provided that normal arrangements are in place for clinical governance, consent and audit.
1.2 During the consent process clinicians should ensure that patients understand that the procedure is likely to be irreversible and that if vision deteriorates in the other eye it poses a potential threat to their eyesight.
1.3 Patients should only be offered implantation of an opaque intraocular lens when all alternative treatment options for their double vision have proved inadequate.
2 The procedure
2.1 Indications and current treatments
2.1.1 Double vision (also known as diplopia) occurs when a person sees two images of a single object instead of one. It most commonly results from the eyes pointing in different directions. Binocular double vision may be caused by disorders affecting the eye muscles or other conditions such as brain tumours, diabetes, thyroid disease or severe head injury. This form of double vision may stop if either eye is covered. Occasionally, people may have monocular double vision (one eye only), usually caused by a type of cataract. The procedure described in this guidance may not be suitable for monocular double vision. 
2.1.2 Treatment of binocular double vision depends on its underlying cause and prognosis. It may include wearing a patch over one eye, use of filters on spectacles, use of an opaque contact lens in one eye, eye muscle botulinum toxin injection or eye muscle surgery. Some patients, particularly children, may be able to ignore the image from one eye.
2.2 Outline of the procedure
2.2.1 Implantation of an opaque lens for intractable double vision is carried out with the patient under local or general anaesthesia. It involves the insertion of an opaque intraocular lens (IOL) (similar to standard cataract surgery) or an iris claw lens.
2.2.2 Two different techniques can be used. The technique involving removal of the natural lens achieves this by phacoemulsification or extracapsular surgery (to extract the lens in fragments or in one piece, respectively, similar to standard cataract surgery). An opaque IOL is then inserted through the corneal incision and placed in the capsular bag or sulcus (cleft). In the alternative technique (implantation of an iris claw lens) a specially manufactured tinted lens may be surgically attached to the iris in the anterior chamber of the eye. The lens has a claw-like mechanism that attaches to the iris tissue by pinching it. Using this technique, the eye's natural lens is kept in place.
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/IP62overview.
2.3 Efficacy
2.3.1 In a case series of 12 patients, the mean visual function score after implantation of an opaque IOL was 92 (measured by the 14-item Visual Function scale [0–100 from maximum disability to no disability]) at a mean follow-up of 21 months (preoperative score not measured). One patient in the case series of 12 patients reported persistence of double vision that resolved with medical treatment. Case reports of six patients, including two patients with intractable double vision, stated that all patients had improved symptoms (not otherwise stated) after opaque IOL implantation at a mean follow-up of 14 months. Case reports of two patients described improvement in double vision in both patients after implantation of an opaque IOL (duration of follow-up not stated). In a case report of one patient, double vision resolved completely after implantation of an opaque IOL and a good result was reported to be maintained at 14-year follow-up.
2.3.2 The case series of 12 patients reported that mean patient satisfaction score following the procedure was 3.4 (on a scale ranging from 0 [unhappy] to 4 [very happy]).
2.3.3 The Specialist Advisers considered the key efficacy outcomes to be eradication of or improvement in symptoms of diplopia without discomfort to the eye. They stated that there were no concerns about the efficacy of the procedure.
2.4 Safety
2.4.1 In the case series of 12 patients, one IOL broke during insertion; another IOL was successfully implanted into the eye 6 months later (mean follow-up 21 months).
2.4.2 The case report of six patients recorded mild IOL subluxation (partial dislocation of the lens) in one patient with leukocoria (time of occurrence not stated). However, this did not adversely affect patient satisfaction.
2.4.3 The Specialist Advisers stated that there is concern about the blocking of vision in a functioning eye, since development of a sight-threatening condition in the other eye would leave the patient with impaired vision, and it is difficult to reverse the procedure. They listed theoretical adverse events to include failure to recognise pathology (such as a malignant tumour) in the implanted eye because the fundus is obscured from examination by the opaque lens, dislocation of the opaque lens and raised intraocular pressure. They considered that an iris claw IOL presents a theoretical risk of damage to the natural lens of the eye.

Bruce Campbell

Chairman, Interventional Procedures Advisory Committee

September 2008

This page was last updated: 30 March 2010