Implantation of miniature lens systems for advanced age-related macular degeneration: interventional procedures consultation
NATIONAL INSTITUTE FOR HEALTH AND CLINICAL EXCELLENCE
Interventional Procedure Consultation Document
Implantation of miniature lens systems for advanced age-related macular degeneration
| Age-related macular degeneration is an eye disorder affecting central vision that usually occurs in later life. The procedure involves removing the natural lens of the eye through a small incision at the front of the eye and implanting a combination of artificial lenses with the aim of helping to improve central vision. |
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The National Institute for Health and Clinical Excellence is examining implantation of miniature lens systems for advanced age-related macular degeneration and will publish guidance on its safety and efficacy to the NHS in England, Wales, Scotland and Northern Ireland. The Institute'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 miniature lens systems for advanced age-related macular degeneration.
Note that this document is not the Institute's formal guidance on this procedure. The recommendations are provisional and may change after consultation. The process that the Institute will follow after the consultation period ends is as follows.
For further details, see the Interventional Procedures Programme manual, which is available from the Institute's website (www.nice.org.uk/ipprocessmanual). 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 We also ask consultees to highlight any ways in which draft guidance fails to promote equality or tackle discrimination and how it might be improved. Closing date for comments: 23 May 2008 |
| 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 | Evidence on the efficacy of implantation of miniature lens systems for advanced age-related macular degeneration (AMD) shows that the procedure can improve both vision and quality of life. Short tem safety data are available for limited numbers of patients. There is currently insufficient long-term evidence. Therefore this procedure should only be used with special arrangements for clinical governance, consent and audit or research. |
| 1.2 |
Clinicians wishing to undertake implantation of miniature lens systems for advanced AMD should take the following actions.
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| 1.3 | Patient selection is crucial and should include detailed assessment of the patient's ability to process visual stimuli following the operation. The presence of cataract requiring operative treatment may influence the decision to implant a lens system for AMD. |
| 1.4 | Further publication of safety and efficacy outcomes will be useful, specifically with regard to longer term follow-up. The Institute may review the procedure upon publication of further evidence. |
| 2 | The procedure | ||
| 2.1 | Indications and current treatments | ||
| 2.1.1 | The macula is a small area at the centre of the retina, responsible for central vision and the appreciation of fine detail and colour. Damage to the macula impairs vision and, in advanced countries, AMD is the most common cause of blindness. There are two main types of AMD: 'dry' (or atrophic), which is most common, and 'wet' (or neovascular). Both eyes are usually affected, sometimes sequentially. | ||
| 2.1.2 | For early-stage wet AMD, treatments include laser photocoagulation, photodynamic therapy or intravitreal injections of anti-vascular endothelial growth factor agents. There is currently no treatment for dry AMD. Patients with advanced AMD can benefit from optical aids such as magnifying glasses. | ||
| 2.2 | Outline of the procedure | ||
| 2.2.1 | Implantation of lens systems for advanced AMD is usually performed under local anaesthesia. The natural lens is removed through a small incision at the limbus (the area where cornea meets the sclera) and the new lens system inserted. Viscoelastic fluid is used to facilitate insertion. Artificial lens systems can consist of a single miniature telescope prosthesis or a combination of individual lenses implanted separately. The exact technique for implantation may vary according to the system being used. Some lens systems simply magnify the retinal image, usually by a factor of 2-4. Other systems magnify the retinal image and deflect it towards a less damaged part of the macula, while the other eye is used for peripheral vision. After implantation, patients usually require visual rehabilitation. | ||
| Sections 2.3 and 2.4 describe efficacy and safety outcomes which were available in the published literature and which the Committee considered as part of the evidence about this procedure. For more details, refer to the Sources of evidence. | |||
| 2.3 | Efficacy | ||
| 2.3.1 | A non-randomised study of 217 patients reported that 67% (128/192) and 68% (130/192) of eyes with an implanted lens system improved by three or more lines of best-corrected distance and near visual acuity respectively, compared with 13% (24/192) and 33% (64/192) of non-implanted fellow eyes (p < 0.0001) at 1-year follow-up. Loss of two or more lines of best-corrected distance visual acuity was reported in 2% of implanted eyes and 9% of fellow eyes at 1-year follow-up (p = 0.005). In a case series of 35 patients (40 eyes), best-corrected distance visual acuity improved in all patients after a mean of 20 months. | ||
| 2.3.2 | The Specialist Advisers considered key efficacy outcomes to include near and distance visual acuity, reading speed and improved ability to navigate unfamiliar surroundings. | ||
| 2.4 | Safety | ||
| 2.4.1 | A non-randomised study of 217 patients reported that two patients developed corneal decompensation and underwent device removal and corneal transplantation (more than 1 year after initial surgery). | ||
| 2.4.2 | In the same study, 5% (11/217) of procedures were aborted because of complications (posterior capsule rupture, choroidal effusion/haemorrhage and zonular dehiscence). Implants were removed from two eyes after 1 month because of condensation in the telescope. In a case series of 40 patients the implant was removed in 17% (6/36) because of patient dissatisfaction (3), condensation in the telescope (2) and diplopia (1). | ||
| 2.4.3 | In the study of 217 patients and the case series of 40 patients, other complications included increased intraocular pressure requiring treatment (28% [57/206]), corneal oedema (25% [9/36], 7% [14/206]), hypopyon (11% [4/36]), iris sphincter erosion/iris prolapse (3% [1/36], 6% [12/206]), corneal abrasion (5% [11/206]), synechia (6% [13/206], 19% [7/36]) and posterior capsule opacification (3% [1/35], 11% [4/36]). | ||
| 2.4.4 | Two Specialist Advisers reported corneal endothelial cell loss as an adverse event. The Advisers considered additional theoretical complications to include corneal decomposition, corneal or macular oedema, infection, retinal detachment and falls due to inability to adapt. One Adviser commented that the procedure has more risks than standard cataract surgery, including a higher risk of glaucoma and the need for device removal due to inability to adapt. | ||
| 3 | Further information | ||
| 3.1 | This guidance requires that clinicians undertaking the procedure make special arrangements for audit. The Institute has identified relevant audit criteria and is developing an audit tool (which is for use at local discretion), which will be available when the guidance is published. | ||
| 3.2 | The Institute has produced interventional procedures guidance on macular translocation, radiotherapy, and transpupillary thermotherapy for AMD (www.nice.org.uk/IPG048, www.nice.org.uk/IPG049, www.nice.org.uk/IPG058) and technology appraisals guidance on photodynamic therapy for AMD (www.nice.org.uk/TA068). A technology appraisal on ranibizumab and pegaptanib for AMD is currently in development. | ||
Bruce Campbell
Chairman, Interventional Procedures Advisory Committee
April 2008
| Appendix: | Sources of evidence |
| The evidence considered by the Interventional Procedures Advisory Committee is described in the overview, available at: www.nice.org.uk/ip375overview. | |
