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H. M. Dunbar, M. Wilkins, A. Tufail, G. S. Rubin; IMT-UK: A Prospective Multicentre Clinical Study of the Implantable Miniature Telescope (IMT) in Patients With Age-Related Macular Degeneration. Invest. Ophthalmol. Vis. Sci. 2010;51(13):6015.
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The IMT (Visioncare, Saratoga) is an intraocular implant designed for those with moderate to severe vision loss through AMD. It is available in 2 models: the 2.2x and 3x. As a follow up to the IMT-002 trial, IMT-UK aims to evaluate the vision parameters important in patient selection and post-implantation management. The trial is being conducted at Moorfields Eye Hospital, London and 3 other UK centres. Here we present interim results from Moorfields Eye Hospital.
Notable differences in study design exist between IMT-002 and IMT-UK. IMT-UK uses an updated simulator telescope prior to surgery and requires potential candidates to gain 2 extra lines of visual acuity, double that of the US trial. Better eyes are implanted with the 3x model only in the UK where worse eyes were implanted with the 2.2x or 3x model in the US. Participants in the UK undergo a standardised 12-week rehabilitation programme aimed at integrating the new visual status with daily life. 6 rehabilitation sessions were offered on the US trial, but no protocol was issued to providers. Following ophthalmic and optometric examination, eligible patients received phakoemusification and implantation of the IMT under local anaesthesia. A baseline visual function assessment is carried out prior to surgery and repeated at 1, 3, 6 and 12 months. Self-reported visual disability is assessed using the National Eye Institute Visual Functioning Questionnaire (VFQ) and the Massof Activity Inventory (AI).
6 participants (mean 77yrs, 5 female) with mean VA 1.06 logMAR (range 0.88 - 1.34) have been implanted and followed up for at least 3 months. No surgical complications have been encountered to date. Mean distance VA improved significantly by 0.36 logMAR (p = 0.004) at 3 months after surgery. Modest improvements were also seen in reading performance but these failed to reach statistical significance. Contrast sensitivity was significantly reduced at 3 months by 0.40 log units (p = 0.02). VFQ and AI results suggest an overall improvement in self-reported visual disability, but again these were not statistically significant.
The IMT significantly improves distance VA but reduces CS at 3 months. Reading performance and self reported visual disability measures show a trend towards improvement. Overall these results suggest that the IMT may be of benefit to carefully selected patients as part of a programme of rehabilitation.
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