Tenotomy of four horizontal eye muscles for nystagmus (interventional procedures consultation)
NATIONAL INSTITUTE FOR HEALTH AND CLINICAL EXCELLENCE
Interventional Procedure Consultation Document
Tenotomy of four horizontal eye muscles for nystagmus
| Nystagmus is an involuntary movement of the eyes (most commonly from side to side) usually associated with impaired vision. In tenotomy, the horizontal muscles of the eye (which move the eye side to side) are cut and re-attached either at the same place or in a position further back on the eyeball to address squint or abnormal head posture. The aim of the procedure is to slow the involuntary eye movements and improve vision. |
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The National Institute for Health and Clinical Excellence (NICE) is examining the tenotomy of four horizontal eye muscles for nystagmus 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 the tenotomy of four horizontal eye muscles for nystagmus. 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:
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.
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 We also ask consultees to highlight any ways in which draft guidance fails to promote equality or tackle discrimination and give suggestions for how it might be improved.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: 21 October 2008 Target date for publication of guidance: January 2008 |
| Note that this document is not the Institute's guidance on this procedure. The recommendations are provisional and may change afterconsultation. |
| 1 | Provisional recommendations |
| 1.1 | Current evidence on tenotomy of four horizontal eye muscles for nystagmus is based on small numbers of patients, but indicates some efficacy, particularly improvement of head posture. There are no major safety concerns about the procedure, which is technically similar to surgery for strabismus (also known as squint or heterotropia). Therefore, this procedure can be used with normal arrangements for clinical governance, consent, and audit. |
| 1.2 | Patients should be selected for this procedure and treated only by ophthalmologists with experience in ocular motility disorders. |
| 2 | The procedure |
| 2.1 | Indications and current treatments |
| 2.1.1 | Nystagmus is an involuntary oscillatory movement of the eyes, usually from side to side, but sometimes up and down or in a circle, which frequently disturbs vision. |
| 2.1.2 | Nystagmus may be associated with an abnormal head position since the head is held in a position of gaze where the nystagmus has the least effect and vision is therefore least impaired (known as a null zone). People with nystagmus may additionally have strabismus. |
| 2.1.3 | Nystagmus may develop at different times of life. It may be congenital (from birth) or infantile (developing during the first 6 month of life) and may be associated with disabilities and conditions such as Down's syndrome. Acquired nystagmus may occur as a result of conditions such as stroke or multiple sclerosis. |
| 2.1.4 | There is currently no cure for nystagmus. Treatments that have been used include anti-epileptic drugs and injections of botulinum toxin. Lenses may be worn to improve visual acuity, but they do not correct nystagmus. |
| 2.2 | Outline of the procedure |
| 2.2.1 | With the patient under general anaesthesia, an incision is made in the conjunctiva and tenotomy is carried out of the two horizontal rectus muscles (lateral and medial) of each eye, detaching them from the sclera. The muscles are re-attached either in their original positions or further back on the eyeball (retroequatorial recession). |
| 2.2.2 | The exact surgical technique, particularly the extent of retroequatorial recession (if any), depends on ocular alignment and the presence or absence of abnormal head posture and strabismus. |
| 2.2.3 | The procedure aims to reduce the frequency and amplitude of nystagmus by weakening the horizontal eye muscles. |
| 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/IP704overview. | |
| 2.3 | Efficacy |
| 2.3.1 | In a case series of 21 patients, 95% (20/21) had an improvement in both abnormal head turn and tilt at mean follow-up of 19 months. Two case series of 20 and 12 patients reported improved head posture in all patients who had abnormal head posture pre‑operatively (n = 7 and 4, respectively). In a case series of 10 patients, 3 of 5 with abnormal head posture improved while 2 did not (follow-up not stated). |
| 2.3.2 | Case series of 20, 18, 12, 12 and 10 patients reported changes in visual acuity (as assessed by a Snellen chart) respectively, of: an increase of 3, 2 and 1 lines in 2, 8 and 3 patients (2 had no change; 2 had a decrease) (mean follow-up: 12 months); an increase of 1 line in 50% (9/18) at 3 months' follow-up; an increase of at least 2 lines in 58% (7/12), 1 line in 3 and a loss of 1 line in 1 (mean follow-up: 13 months); an increase of 1 to 3 lines in 75% (9/12) (mean follow-up: 16 months); and an average increase of 1 line in 87% (7/8) of patients assessed (follow-up not stated). In a further case series of 12 patients, mean binocular decimal visual acuity (1.0 = 20/20 vision or 8 Snellen lines) in the primary position improved from 0.30 at baseline to 0.47 after 1 week (p = 0.011) and 0.46 after 3 months (p-value not stated). |
| 2.3.3 | Two studies reported levels of patient satisfaction with the procedure. In the case series of 18 patients, 8 were pleased, 4 were indifferent, 2 were displeased and 4 did not respond (percentages not reported). In the same group, 8 patients stated that the procedure had not changed their daily life and 4 reported some improvement in daily activities. In a case series of 12 patients, 83% (10/12) reported that they had better control of nystagmus postoperatively. |
| 2.3.4 | The Specialist Advisers considered efficacy outcomes to include visual acuity, null point width, stereoacuity, ocular movement recordings and quality of life. One Specialist Adviser stated that it is difficult to measure improvement and standardise viewing angles. One Specialist Adviser stated that there is uncertainty about the long-term benefit of the procedure. |
| 2.4 | Safety |
| 2.4.1 | Six case series of 75, 21, 20, 12, 12 and 10 patients reported that no complications occurred. |
| 2.4.2 | In a case series of 18 patients, 2 developed exotropia (divergent strabismus), 1 had asthenopic symptoms (eye strain, fatigue and redness) and there was one case of scleral perforation during the procedure. All 18 patients reported severe pain in the first 24 hours postoperatively and still had discomfort at 2 week follow-up. |
| 2.4.3 | One case series of 12 patients reported that all patients had mild limitation of horizontal eye movement in the direction of muscle recession 1 week after the procedure. At 3-month follow-up 8 patients still had some limitation and 4 had no or minimal limitation. |
| 2.4.4 | The Specialist Advisers considered theoretical adverse events to include loss of vision, retinal damage, need for revision surgery, damage to the eye, redness, diplopia, infection, perforation of the globe, slipped muscles and induced strabismus. |
Bruce Campbell
Chairman, Interventional Procedures Advisory Committee
September 2008
This page was last updated: 30 March 2010