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Ophthalmology. 2017 Oct;124(10):1556-1564. doi: 10.1016/j.ophtha.2017.05.028. Epub 2017 Jun 23.

Magnetic Oculomotor Prosthetics for Acquired Nystagmus.

Author information

1
Institute of Neurology, University College London, London, United Kingdom. Electronic address: p.nachev@ucl.ac.uk.
2
Orbital Clinic, Moorfields Eye Hospital NHS Foundation Trust, London, United Kingdom; National Institute for Health Research Biomedical Research Centre, Institute of Ophthalmology, Bath Street, London, United Kingdom.
3
Orbital Clinic, Moorfields Eye Hospital NHS Foundation Trust, London, United Kingdom.
4
Department of Clinical Neurology, University of Oxford, Oxford, United Kingdom.
5
Strabismus Clinic, Moorfields Eye Hospital NHS Foundation Trust, London, United Kingdom.
6
Healthcare Biomagnetics Laboratory, University College London, London, United Kingdom.

Abstract

PURPOSE:

Acquired nystagmus, a highly symptomatic consequence of damage to the substrates of oculomotor control, often is resistant to pharmacotherapy. Although heterogeneous in its neural cause, its expression is unified at the effector-the eye muscles themselves-where physical damping of the oscillation offers an alternative approach. Because direct surgical fixation would immobilize the globe, action at a distance is required to damp the oscillation at the point of fixation, allowing unhindered gaze shifts at other times. Implementing this idea magnetically, herein we describe the successful implantation of a novel magnetic oculomotor prosthesis in a patient.

DESIGN:

Case report of a pilot, experimental intervention.

PARTICIPANT:

A 49-year-old man with longstanding, medication-resistant, upbeat nystagmus resulting from a paraneoplastic syndrome caused by stage 2A, grade I, nodular sclerosing Hodgkin's lymphoma.

METHODS:

We designed a 2-part, titanium-encased, rare-earth magnet oculomotor prosthesis, powered to damp nystagmus without interfering with the larger forces involved in saccades. Its damping effects were confirmed when applied externally. We proceeded to implant the device in the patient, comparing visual functions and high-resolution oculography before and after implantation and monitoring the patient for more than 4 years after surgery.

MAIN OUTCOME MEASURES:

We recorded Snellen visual acuity before and after intervention, as well as the amplitude, drift velocity, frequency, and intensity of the nystagmus in each eye.

RESULTS:

The patient reported a clinically significant improvement of 1 line of Snellen acuity (from 6/9 bilaterally to 6/6 on the left and 6/5-2 on the right), reflecting an objectively measured reduction in the amplitude, drift velocity, frequency, and intensity of the nystagmus. These improvements were maintained throughout a follow-up of 4 years and enabled him to return to paid employment.

CONCLUSIONS:

This work opens a new field of implantable therapeutic devices-oculomotor prosthetics-designed to modify eye movements dynamically by physical means in cases where a purely neural approach is ineffective. Applied to acquired nystagmus refractory to all other interventions, it is shown successfully to damp pathologic eye oscillations while allowing normal saccadic shifts of gaze.

Comment in

PMID:
28651813
PMCID:
PMC5609850
DOI:
10.1016/j.ophtha.2017.05.028
[Indexed for MEDLINE]
Free PMC Article

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